Details of a Researcher - UMEZAWA Osamu

Papers - UMEZAWA Osamu

about 238

Role of Hardness Distribution on Pitting Strength in Rolling-sliding Contact Fatigue for Nitrided-SCM440H

Maruyama Takashi, Umezawa Osamu

Tetsu-to-Hagane 112 ( 5 ) 233 - 242 2026.5

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：The Iron and Steel Institute of Japan Single Work

This study aims to clarify the influence of hardness distribution on the pitting fatigue strength of nitrided steels. Gas nitriding with controlled nitriding potential was applied to SCM440H and 31CrMoV9 steels, and roller pitting tests were conducted. The nitrided specimens exhibited superior pitting fatigue strength compared with carburized specimens at 107 cycles, corresponding to the fatigue limit. In contrast, under high contact pressure, early pitting occurred within 105 cycles, indicating reduced fatigue performance in the finite-life. The pitting fatigue strength of nitrided steels strongly depended on the case-hardened depth, and specimens with deeper hardened layers demonstrated higher durability. Under high contact pressure, most of the plastic deformation occurred in the early stage of testing, whereas work hardening developed progressively with increasing number of cycles. In nitrided steels, such plastic deformation induces tensile stress at the contact surface, and in combination with frictional stress, promotes the formation of vertical cracks originating from the compound layer. Therefore, increasing the case-hardened depth is effective for suppressing early pitting by reducing plastic deformation. For nitride steels, pre-running to induce work hardening also mitigated early pitting without reliance on alloying elements or prolonged nitriding durations. These findings indicate that, even when flaking initiates from the surface, the hardened layer depth plays a critical role in the rolling–sliding contact fatigue performance of nitrided steels. Consequently, for components such as gears that operate under rolling–sliding contact, it is essential to consider the influence of internal shear stress in strength design to achieve superior pitting fatigue strength.

Visualization of strain distribution developed during high-cycle fatigue bending test in 780 MPa high-strength steels with various microstructures

Norimitsu Koga, Masaru Sakurai, Osamu Umezawa, Huyen Thi Doan, Sota Goto

ISIJ International 66 ( 4 ) 557 - 580 2026.3 [Reviewed]

DOI Web of Science CiNii Research

Language：English Publishing type：Research paper (scientific journal) Publisher：一般社団法人日本鉄鋼協会 Single Work

The strain distribution developed during high-cycle fatigue bending tests exceeding 106 cycles was visualized in 780 MPa high-strength steels with various microstructures using the digital image correlation (DIC) method for the secondary electron images of the specimen surface. The tensile stress was approximately identical among the steels with ferrite (F), bainite (B), and ferrite + pearlite (FP) microstructures. Microcracks were detected in the B and FP steels after the fatigue bending test, whereas no cracks were present in the F steel even after 106 cycles. The strain distribution developed in the high-cycle fatigue bending test was successfully visualized using the DIC method for the first time. The strain was inhomogeneously distributed for up to 102 cycles even under an applied stress less than the yield stress. The average strain along the loading direction was approximately zero regardless of the number of cycles for all specimens. The standard deviation calculated from the strain histogram continuously increased with an increasing number of cycles for all steels. This suggests that strain gradually accumulated during the fatigue test. Microcracks tended to nucleate in high-strain regions. The plane of the microcrack was the slip plane, and its Schmid factor was high. Therefore, the microcracks were generated through intrusion and extrusion mechanisms with local slip deformation at the specimen surface.

Effects of martensite matrix structure and retained-austenite distribution on low-temperature toughness of 9%Ni steel with intermediate treatment

Metallurgical Materials Transactions A 57 ( 3 ) 1299 - 1320 2026.3 [Reviewed]

DOI Web of Science

Authorship：Corresponding author Language：English Publishing type：Research paper (scientific journal) Single Work

Rolling-sliding contact fatigue of carbonitrided SCM420 steel

Yoshihiro Nishiumi, Osamu Umezawa

Springer Proceedings in Materials 107 99 - 106 2026.2 [Reviewed] [Invited]

DOI

Authorship：Corresponding author Language：English Publishing type：Research paper (international conference proceedings) Single Work

Effect of manganese on cryogenic toughness of 7 % nickel-added steels with intermediate heat treatment

Sato Yuya, Tachibana Shunichi, Nishiyama Takeshi, Madanbashi Rikiya, Umezawa Osamu, Tagawa Tetsuya

ISIJ International 65 ( 13 ) 2252 - 2259 2025.12 [Reviewed]

DOI Web of Science CiNii Research

Language：English Publishing type：Research paper (scientific journal) Publisher：一般社団法人日本鉄鋼協会 Joint Work

The effect of the manganese content of 7 % nickel-added steel on cryogenic toughness was investigated. Charpy impact tests on steels with manganese contents ranging from 0.05% to 2.16% revealed that the absorbed energy at -196 °C increased with decreasing manganese content. Two steels with manganese contents of 0.2 % and 0.8 % were selected for a more detailed investigation of the dependence of toughness at -196 °C on the intermediate heat treatment temperature, fracture behavior and retained austenite. Although the 0.2 % manganese steel stably exhibited a high absorbed energy at -196 °C at all intermediate heat treatment temperatures examined in this work, it was necessary to select an appropriate intermediate heat treatment temperature for the 0.8 % manganese steel in order to achieve high absorbed energy at -196 °C. The volume fraction, size, and nickel content of retained austenite were quantified using XRD and SEM/EDS, and the characteristics of the retained austenite in the steels with low manganese alloy designs were investigated. The cleavage-type brittle fracture that appeared in some specimens was discussed from the viewpoint of the stability of retained austenite.

Pore Shape Evolution in Nitrided SCM440H Compound Layer and Its Influence on Pitting Resistance during Rolling-sliding Contact Fatigue

Maruyama Takashi, Umezawa Osamu

ISIJ International 65 ( 11 ) 1701 - 1709 2025.10 [Reviewed]

DOI CiNii Research

Language：English Publishing type：Research paper (scientific journal) Publisher：一般社団法人日本鉄鋼協会 Joint Work

Nitriding is a beneficial surface hardening heat treatment to reduce CO2 emissions and shows a potential partially replace carburized steels adopted for sliding parts such as bearings and gears. Both the bending fatigue strength and pitting fatigue strength under high contact pressure were evaluated for nitrided JIS-SCM440H materials using two types of controlled-nitridings, i.e. γ’ and ε, and conventional gas nitriding. Not only the thickness of the compound layer but also its phase structure such as γ’ and ε significantly affected the 107 cycles bending fatigue strength, where the γ’-nitrided specimen was the highest. On the other hand, almost no effects of the thickness and phase structure on the 107 cycles pitting fatigue strength were detected in the specimens. Compared to the carburized specimen, the γ’-nitrided specimen exhibited higher 107 cycles fatigue strength in bending and pitting, but poor fatigue strength in the lower cycles range. The shape and size of the pores in the compound layer were altered during roller-pitching tests, although there was almost no reduction in the thickness of the compound layer. The pore size was reduced by pore closure, especially at higher contact pressures. Pore closure was more pronounced in the γ’-nitrided specimens than in the ε-nitrided specimens at lower contact pressures. The 107 cycles pitting fatigue strength was improved after the pore closure, resulting from fewer defects.

Enhanced work hardening in ferrite and austenite of duplex stainless steel at 200 K: In situ neutron diffraction study

Takayuki Yamashita, Norimitsu Koga, Mao Wenqi, Wu Gong, Takuro Kawasaki, Stefanus Harjo, Hidetoshi … Show more authors

Materials Science and Engineering A 941 148602 - 148602 2025.9 [Reviewed]

DOI Web of Science

Language：English Publishing type：Research paper (scientific journal) Single Work

Effect of induction hardening following carburizing–nitriding duplex treatment on the microstructure and fatigue strength of JIS-SCM420 low-alloy steel

Minheon Kim, Osamu Umezawa

Metals 15 ( 9 ) 944 2025.8 [Reviewed] [Invited]

DOI Web of Science

Language：English Publishing type：Research paper (scientific journal) Single Work

Influence of prior quenching and tempering treatment on cementite formation during nitriding at 913 K for SCM440 steel

Kim Minheon, Umezawa Osamu

ISIJ International 65 ( 7 ) 982 - 991 2025.6 [Reviewed]

DOI Web of Science CiNii Research

Language：English Publishing type：Research paper (scientific journal) Publisher：一般社団法人日本鉄鋼協会 Joint Work

This study investigated the mechanism of cementite formation in JIS-SCM440 low-alloy steel subjected to high-temperature nitriding (NH) at 913 K, followed by quenching and aging. Specimens with and without prior quenching and tempering (QT) treatment were analyzed to understand the influence of the initial microstructures on cementite precipitation. Comprehensive characterization using scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), X-ray diffraction (XRD), and electron probe microanalysis (EPMA) revealed that NH treatment promoted significant nitrogen diffusion into the steel matrix, resulting in the formation of a nitrogen compound layer and a hardened nitrogen martensite layer beneath the compound layer. In the NH specimens following QT treatment (QTNH), accelerated carbon diffusion to the surface led to cementite precipitation around the surface pores owing to the dissolution of fine carbides. Cementite enhanced the surface hardness of the porous regions compared to that of the NH specimens.

Effects of β phase and initial dislocation density on dwell fatigue deformation and crack initiation mechanism in Ti-5Al-2Fe-3Mo alloy

Daiki Miyashita, Yusuke Nakao, Osamu Umezawa

Materials Science and Engineering A 924 147852 2025.2 [Reviewed]

DOI Web of Science

Authorship：Corresponding author Language：English Publishing type：Research paper (scientific journal) Joint Work

Pore Shape Evolution in Nitrided SCM440H Compound Layer and Its Influence on Pitting Resistance during Rolling-Sliding Contact Fatigue

Maruyama Takashi, Umezawa Osamu

Tetsu-to-Hagane 111 ( 2 ) 32 - 40 2025.2 [Reviewed]

DOI Web of Science CiNii Research

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：The Iron and Steel Institute of Japan Joint Work

Nitriding is a beneficial surface hardening heat treatment to reduce CO2 emissions and shows a potential partially replace carburized steels adopted for sliding parts such as bearings and gears. Both the bending fatigue strength and pitting fatigue strength under high contact pressure were evaluated for nitrided JIS-SCM440H materials using two types of controlled-nitridings, i.e. γ' and e, and conventional gas nitriding. Not only the thickness of the compound layer but also its phase structure such as γ' and e significantly affected the 107 cycles bending fatigue strength, where the γ'-nitrided material was the highest. On the other hand, almost no effects of the thickness and phase structure on the 107 cycles pitting fatigue strength were detected in the materials. Compared to the carburized material, the γ'-nitrided material exhibited higher 107 cycles fatigue strength in bending and pitting, but poor fatigue strength in the lower cycles range. The shape and size of the pores in the compound layer were altered during roller-pitching tests, although there was almost no reduction in the thickness of the compound layer. The pore size was reduced by pore closure, especially at higher contact pressures. Pore closure was more pronounced in the γ'-nitrided materials than in the ε-nitrided materials at lower contact pressures. The 107 cycles pitting fatigue strength was improved after the pore closure, resulting from fewer defects.

Influence of carbonitriding and sub-zero treatment on the microstructure and fatigue strength of JIS-SCM420 low-alloy steel

Kim Minheon , Umezawa Osamu

Materials Science and Engineering A 923 147751 - 147751 2025.2 [Reviewed]

DOI Web of Science CiNii Research

Language：English Publishing type：Research paper (scientific journal) Joint Work

Role of dislocation characteristics on deformation behavior of martensitic steel analyzed by neutron diffraction

Dannoshita Hiroyuki, Hasegawa Hiroshi, Higuchi Sho, Matsuda Hiroshi, Gong Wu, Kawasaki Takuro, Harj … Show more authors

Proceedings of International Symposia on Steel Science 2024 ( 0 ) 209 - 212 2024.11

DOI CiNii Research

Language：English Publishing type：Research paper (international conference proceedings) Publisher：一般社団法人日本鉄鋼協会 Joint Work

The deformation behavior of lath martensite has been extensively explored, with this study focusing on its characteristics through the lens of dislocation theory. We conducted an in-situ neutron diffraction study to investigate the tensile deformation behavior of ultra-low carbon Fe–18Ni alloy under different heat treatment conditions. These alloys were initially quenched and then tempered at 573 K and 773 K. This study aimed to quantitatively evaluate dislocation characteristics and understand their role in the resulting stress–strain curves. To achieve this, we applied the convolutional multiple whole profile (CMWP) method, which determines the microstructural parameters from diffraction line profiles, linking macroscopic deformation behavior with quantitative information on dislocation characteristics without relying solely on local information. The CMWP method evaluates the dislocation characteristics, such as density, arrangement, and character. Our findings revealed that a high dislocation density in the quenched state, which gradually decreased with increasing tempering temperature, affected the mechanical properties such as the tensile strength. Additionally, we closely monitored also changes in the arrangement and character of dislocations as tempering temperature increased and during deformation. The parameters played a crucial role in revealing the evolution of flow stresses.

Effect of Manganese on Cryogenic Toughness of 7% Nickel-added Steels with Intermediate Heat Treatment

Sato Yuya, Tachibana Shunichi, Nishiyama Takeshi, Madanbashi Rikiya, Umezawa Osamu, Tagawa Tetsuya

Tetsu-to-Hagane 110 ( 11 ) 871 - 879 2024.9 [Reviewed]

DOI Web of Science CiNii Research

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：The Iron and Steel Institute of Japan Joint Work

The effect of the manganese content of 7 % nickel-added steel on cryogenic toughness was investigated. When Charpy absorbed energy was investigated in the steels with wide range manganese content from 0.05 % to 2.16 %, the absorbed energy at −196 °C increased with a decrease of manganese content. The two steels with manganese contents of 0.2 % and 0.8 % were selected for use in a more detailed investigation regarding the dependence of toughness at −196 ℃ on the intermediate heat treatment temperature, fracture behaviors and the retained austenite. Although the 0.2 % manganese steel stably exhibited a high absorbed energy at −196 ℃ at all intermediate heat treatment temperatures examined in this work, it was necessary to select an appropriate intermediate heat treatment temperature for the 0.8 % manganese steel in order to　achieve high absorbed energy at −196 ℃. The total amount of the retained austenite and the size and the nickel content locally segregated into an identical retained austenite were quantified by using XRD and SEM/EDS, and the characteristics of the retained austenite in the steels with low manganese alloy designs were investigated. The cleavage-type brittle fracture that appeared in some specimens was discussed from the viewpoint of the stability of retained austenite.

Understanding crack growth within the γ’ Fe4N layer in a nitrided low carbon steel during monotonic and cyclic tensile testing

Rama Srinivas Varanasi, Motomichi Koyama, Mizuho Yokoi, Yusuke Ootani, Momoji Kubo, Kento Tanahara, … Show more authors

Journal of Materials Science 59 ( 31 ) 14639 - 14652 2024.7 [Reviewed]

DOI Web of Science

Language：English Publishing type：Research paper (scientific journal) Joint Work

Strength and fracture toughness of type 304 and 316 austenitic stainless steels at 4.2 K

Takeru Sakurai, Osamu Umezawa, Yoshinori Ono

IOP Conference Series: Materials Science and Engineering 1302 012002 2024.7 [Reviewed]

DOI Web of Science

Authorship：Corresponding author Language：English Publishing type：Research paper (international conference proceedings) Single Work

High-cycle fatigue strength of 22Cr-12Ni austenitic stainless steel at 77 K

Muhammad Edgar Bratasena, Tetsuya Kato, Osamu Umezawa, Yoshinori Ono, Masayuki Komatsu

IOP Conference Series: Materials Science and Engineering 1302 012001 2024.7 [Reviewed]

DOI Web of Science

Authorship：Corresponding author Language：English Publishing type：Research paper (international conference proceedings) Single Work

{001}<101> texture evolution by preferential dynamic grain growth in Ti-37 mol%Nb alloy under plane strain compression at high temperatures

Umezawa Osamu, Hayakawa Yujiro, Schindler Ivo, Fukutomi Hiroshi

MATERIALS TRANSACTIONS 65 ( 3 ) 282 - 291 2024.3 [Reviewed]

DOI CiNii Research

Authorship：Lead author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：公益社団法人日本金属学会 Joint Work

{001}〈101〉 texture evolution in Ti–37 mol%Nb (Nb–46.5 mass%Ti) alloy was determined under plane strain compression at the temperatures of 800°C, 950°C, and 1100°C, in which preferential dynamic grain growth (PDGG) took place. At lower temperature and higher strain rate such as 800°C–10−2/s, almost no grain growth occurred in the transverse direction (TD), and the α-fiber + near {111}〈110〉 in the γ-fiber texture was developed, which was a stable orientation as deformation texture. At higher temperature and lower strain rate such as 1100°C–10−3/s, the grain growth along the TD remarkably appeared by grain boundary bulging, and an extremely high pole density of the texture near the α-fiber, especially the rotated cube {001}〈101〉, evolved. A planar dislocation structure with pile-ups appeared and individual dislocations were uniformly distributed in the grains. The rotated cube texture fulfills the conditions of the deformation stability and the low Taylor factor in accordance with the PDGG mechanism. The essential aspect of the mechanism is the preferential growth of grains with a stable orientation for deformation and a low Taylor factor in the given deformation mode.

High-strength and high-toughness austenitic stainless steels based on type 316LN at 4.2 K

Takeru Sakurai, Osamu Umezawa,

Cryogenics 136 103762 - 103762 2023.12 [Reviewed]

DOI Web of Science CiNii Research

Language：English Publishing type：Research paper (scientific journal) Single Work

Effects of dislocation arrangement and character on the work hardening of lath martensitic steels

Hiroyuki Dannoshita, Hiroshi Hasegawa, Sho Higuchi, Hiroshi Matsuda, Wu Gong, Takuro Kawasaki, Stef … Show more authors

Scripta Materialia 236 115648 2023.11 [Reviewed]

DOI Web of Science CiNii Research Repository

Language：English Publishing type：Research paper (scientific journal) Publisher：Elsevier Single Work

Work-hardening behavior of a lath martensitic Fe–18Ni alloy during tensile deformation is discussed based on the Taylor's equation. The dislocation characteristics are monitored using in situ neutron diffraction. In the specimens of as-quenched (AQ) and tempered at 573 K (T573), the dislocations are extremely dense and randomly arranged. The dislocations in AQ and T573 form dislocation cells as deformation progresses. Consequently, a composite condition comprising cell walls and cell interiors is formed, and the coefficient α in the Taylor's equation increases. Cells are already present in the specimen tempered at 773 K (T773), which has a low dislocation density and a large fraction of edge-type dislocations. As deformation continues, the dislocation density of T773 increases, its cell size decreases, and its composite condition become stronger. Simultaneously, the edge-type dislocation fraction decreases, keeping α unchanged. Thus, both the dislocation arrangement and character affected α, thereby affecting the work-hardening behavior.

High-Temperature Hardness in Hypereutectoid Steels with Various Microstructures Measured by Using Small Ball Rebound Hardness Test

Koga Norimitsu, Koizumi Kouki, Takayasu Shuto, Umezawa Osamu, Watanabe Mizuki, Yamamoto Masayuki, Y … Show more authors

MATERIALS TRANSACTIONS 64 ( 7 ) 1600 - 1604 2023.7 [Reviewed]

DOI Web of Science CiNii Research Repository

Language：English Publishing type：Research paper (scientific journal) Publisher：公益社団法人日本金属学会 Joint Work

The temperature dependence of hardness in hypereutectoid steels with various microstructures was measured by using the small ball rebound hardness test, and the effect of carbon state on the high-temperature hardness was discussed. As-received and spheroidized cementite steels consisted of spheroidized cementite, graphite and ferrite matrix, and the volume fraction of graphite in the spheroidized cementite steel was larger than that in the as-received steel. Pearlite steel had ferrite and cementite lamellar structure without graphite. The characteristic hardening was detected above 700 K in all steels, suggesting that the solid solute carbon enhances the hardness even in hypereutectoid steels with high strength. The pearlite steel exhibited the highest hardness owing to the ferrite and cementite lamellar structure and no graphite. While the spheroidized cementite steel exhibited the lowest hardness, although the size of cementite was finer than that in the as-received steel. It was quantitatively demonstrated that the large volume fraction of graphite caused the low hardness in the spheroidized cementite steel.

Fracture toughness and martensitic transformation in type 316LN austenitic stainless steel extra-thick plates at 4.2 K

Takeru Sakurai, Osamu Umezawa

Materials Science and Engineering A 862 144122 - 144122 2023.1 [Reviewed]

DOI Web of Science CiNii Research

Language：English Publishing type：Research paper (scientific journal) Single Work

Electrochemical, biological and technological properties of anodized titanium for color coded implants

Josef Hlinka, Kamila Dostalova, Kristina Cabanova, Roman Madeja, Karel Frydrysek, Jan Koutecký, Zuz … Show more authors

Materials 16 ( 2 ) 632 2023.1 [Reviewed]

DOI Web of Science PubMed Repository

Language：English Publishing type：Research paper (scientific journal) Publisher：MDPI Single Work

Electrochemical, Biological, and Technological Properties of Anodized Titanium for Color Coded Implants

Hlinka Josef, Dostalova Kamila, Cabanova Kristina, Madeja Roman, Frydrysek Karel, Koutecky Jan, Ryb … Show more authors

Materials 16 ( 2 ) 2023.1 [Reviewed]

CiNii Research

Language：English Publishing type：Research paper (scientific journal) Publisher：MDPI Joint Work

Anodization coloring of titanium tools or implants is one of the common methods for the differentiation of each application by its size or type. Commercial purity titanium grade 4 plates (50 x 20 x 0.1 mm) were tested to obtain their electrochemical and other technological properties. The coloring process was done using the potential of 15, 30, 45, 60, and 75 Volts for 5 s in 1 wt. % citric acid in demineralized water solution. Organic acids solutions generally produce better surface quality compared to inorganic acids. The contact angle of colored surfaces was measured by the sessile drop method. Electrochemical impedance spectroscopy and potentiodynamic polarization were used for the determination of selected electrochemical and corrosion parameters of the tested surfaces. It was found that the anodization process decreases corrosion potential significantly. It was also confirmed that a higher potential used for anodization results in higher polarization resistance but also a decrease in corrosion potential. The anodization process at 75 V produces surfaces with the lowest corrosion rate under 1 nm/year and the noblest corrosion potential. It was confirmed that the anodization process in citric acid does not affect titanium cytotoxicity.

Effects of vanadium addition on strain distribution, crack initiation and propagation during low-cycle fatigue test in ferrite and martensite dual-phase steel

Norimitsu Koga, Akihiro Kaseya, Osamu Umezawa, Hiroshi Nakata, Shunsuke Toyoda

ISIJ International 62 ( 10 ) 2132 - 2134 2022.10 [Reviewed]

DOI Web of Science CiNii Research Repository

Language：English Publishing type：Research paper (scientific journal) Publisher：一般社団法人日本鉄鋼協会 Single Work

Effects of vanadium (V) addition on strain distribution, crack initiation and propagation behavior during low-cycle fatigue test in ferrite and martensite dual phase (DP) steel were revealed. V addition effectively extended the low-cycle fatigue life, even though the tensile properties were approximately identical between V-added DP and DP steels. The stress amplitude suddenly decreased just before fracture in the V-added DP steel. The fatigue crack initiated from the surface and propagated inside, and the brittle fracture occurred in the crack propagation region in the V-added DP steel. The strain distribution introduced during the low-cycle fatigue test was more inhomogeneous for the V-added DP steel than that for the DP steel, and the fatigue crack was generated from the high-strain region. Considering that the number of cycles for crack initiation in the V-added DP steel was larger than that in DP steel, the inhomogeneous strain distribution in the V-added steel promoted crack nucleation but suppressed crack growth in the crack initiation stage. Cracks propagated independent of the strain distribution in the V-added DP steel in the crack propagation stage. The crack propagation rate in the V-added DP steel was remarkably higher than that in DP steel in the crack propagation stage. Thus, V addition effectively extended the number of cycles for crack initiation but caused brittle fracture and faster crack propagation.

Evolution of dislocation structure determined by neutron diffraction line profile analysis during tensile deformation in quenched and tempered martensitic steels

854 143795 2022.9 [Reviewed]

DOI Web of Science

Language：English Publishing type：Research paper (scientific journal) Single Work

Tribofilm properties and microcrack morphologies for a carburized SCM420 steel under high-pressure rolling sliding contact fatigue with lubricants containing high sulfur- and phosphorus-additives

Takayasu Shuto, Umezawa Osamu, Hashimoto Kazuya

WEAR 502-503 204397 2022.8 [Reviewed]

DOI Web of Science CiNii Research Repository

Authorship：Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：Elsevier Science SA Joint Work

Tribofilms and microcracks developed on a carburized SCM420 steel through a two-roller-type pitting test were characterized. Tribofilms composed mainly of calcium phosphate, iron phosphate, and iron oxide were generated on the contact surface. The tribofilms were homogeneously distributed on the contact surfaces that exhibited a longer life, suggesting that the tribofilm distribution affects the rolling sliding contact fatigue (RCF) life. Compounds including the elements from the lubricant were also generated on the surfaces of microcracks formed on the contact surface, suggesting that lubricant flowed into the surface microcracks during the test. The martensitic microstructure at the specimen subsurface was dynamically reconstructed to an ultrafine-grained microstructure during RCF, which resulted in the residual stress relief, especially on the contact surface. After the residual stress release, the fluid pressurization accelerated the formation of a mixed-mode microcrack of mode I and mode II with a high angle to the surface in the later stage, while a shallow microcrack in mode II developed during the early stage.

Tensile properties of 22Cr-12Ni austenitic stainless steel thick plates and bars at cryogenic temperatures

Tetsuya Kato, Yoko Kato, Osamu Umezawa, Yoshinori Ono, Arata Nishimura, Susumu Kumagai, Tetsumi Yuri

IOP Conference Series: Materials Science and Engineering 1241 012001 2022.6 [Reviewed]

DOI

Authorship：Corresponding author Language：English Publishing type：Research paper (international conference proceedings) Joint Work

Effects of grain size and strain rate on the low-temperature tensile properties of ferrite-austenite duplex stainless steel

N. Koga, T. Namiki, O. Umezawa

IOP Conference Series: Materials Science and Engineering 1241 012002 2022.6 [Reviewed]

DOI

Language：English Publishing type：Research paper (international conference proceedings) Joint Work

Statistical Analysis of Influential Factors on the Stability of Retained Austenite in Low Alloy TRIP Steel

Koga Norimitsu, Yamashita Takayuki, Ogawa Keisuke, Umezawa Osamu

MATERIALS TRANSACTIONS 63 ( 5 ) 693 - 702 2022.5 [Reviewed]

DOI Web of Science CiNii Research Repository

Language：English Publishing type：Research paper (scientific journal) Publisher：公益社団法人日本金属学会 Joint Work

The factors representing the stability of retained austenite (γR) in low-alloy TRIP steel at a plastic strain of up to 0.04 were statistically analyzed by evaluating the size, strain level, crystal orientation, morphology, and precipitation site of a large number of γR grains (>1000). The ratio (Rarea) of the area of γR after deformation to that before deformation was adopted as a representative parameter for the stability of γR. The frequency of low Rarea in fine γR was significantly high, indicating that they were unstable. Moreover, it was indicated that γR in the high-strain regions tended to be unstable, whereas γR in the bainite region was stable. The crystal orientation and aspect ratio did not correlate with Rarea in TRIP steel. The strain level and precipitation sites in coarse γR were uncorrelated with Rarea, indicating that the size of the γR has a greater effect on its stability. The stability of γR was not dominated by the carbon concentration but was affected by other factors. The size of γR may represent the stress conditions at the γR/ferrite or bainite boundaries, which is why this factor represents the stability of γR in the TRIP steel at a plastic strain of up to 0.04.

Deformation structure around a crack in γ’-Fe4N layer of nitrided extra-low carbon steel subjected to cyclic tensile test

Norimitsu Koga, Kento Tanahara, Osamu Umezawa

Metallurgical and Materials Transactions A 53 ( 4 ) 1150 - 1155 2022.4 [Reviewed]

DOI Web of Science

Language：English Publishing type：Research paper (scientific journal) Joint Work

Effects of crystallographic texture on subsurface fatigue crack generation in Ti-Fe-O alloy at low temperature

Osamu Umezawa, Weibo Li

ISIJ International 62 ( 3 ) 593 - 601 2022.3 [Reviewed]

DOI Web of Science CiNii Research Repository

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal) Publisher：一般社団法人日本鉄鋼協会 Joint Work

Subsurface microcracks developed in a groove-rolled and cold-swaged Ti–Fe–O alloy were characterized to clarify the generation of subsurface fatigue crack. In addition, the effects of crystallographic texture on subsurface crack initiation and growth were discussed. A considerable number of microcracks were detected in the β grains, α grains, and at the α-β interface. The microcracks in the β grains grew negligibly into the neighboring α grains along the basal plane. This was because these grains were oriented with their c-axis almost perpendicular to the loading axis. The {10 10}α fiber texture prevents the formation of basal facet and its growth on the basal plane. The stress concentration around the microcrack in the β grains could assist the growth of the microcrack into neighboring α grains along the prismatic plane (which is inclined to the loading axis at a suitable angle) or occasionally at a {10 10}α twist boundary. The {10 10}α fiber texture assisted microcrack growth, and thereby, formed aligned facets and yield longer microcrack length. The combination of the shear stress and opening stress on {10 10}α results in a Mode II or III microcrack and causes microcrack growth on the prismatic plane in the neighboring grain.

Crystal plasticity analysis of temperature-sensitive dwell fatigue in Ti-6Al-4V titanium alloy for an aero-engine fan disc

Yin Liangwei, Umezawa Osamu

International Journal of Fatigue 156 106688 2022.3 [Reviewed]

DOI Web of Science CiNii Research Repository

Authorship：Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：Elsevier Science Ltd. Joint Work

This study investigates the temperature-dependent dwell fatigue behavior of Ti-6Al-4V alloy using crystal plasticity finite element method. The dislocation mechanism-based crystal plasticity parameters are calibrated with the data of quasi-static tensile and constant load creep tests at ambient and intermediate temperatures. In particular, the rate-dependent parameters related to slip property are employed to establish the relationship between strain rate sensitivity of a soft alpha-titanium single crystal and temperature. The variation of strain rate sensitivity with temperature influences the stress redistribution occurring within the hard-soft grain combination, which in turn affects the dwell fatigue sensitivity. Further, the structural analysis for a Ti-6Al-4V fan disc provides the stress fields at takeoff and cruise phases to examine the in-service stress redistribution. The highly localized hoop stress and presence of large macrozones at the bore of the fan disc, rather than the fair rate sensitivity of soft macrozones at working temperatures, are responsible for triggering basal stress enhancement and dwell facet nucleation in hard macrozones.

Visualization of strain distribution around fatigue crack introduced by low-cycle fatigue test in high-strength steels using digital image correlation method for replica films

Norimitsu Koga, Yuta Sakamaki, Akihiro Kaseya, Osamu Umezawa, Hiroshi Nakata, Shunsuke Toyoda

Materials Characterization 185 111731 2022.3 [Reviewed]

DOI Web of Science CiNii Research

Language：English Publishing type：Research paper (scientific journal) Publisher：Elsevier Joint Work

Strain distributions around the fatigue crack during the low cycle fatigue of high-strength ferrite + martensite dual-phase (DP) and tempered martensite (Mt) steels were visualized during cycles from the initial state to the crack initiation and crack propagation using a digital image correlation analysis applied to replica films. The replica film successfully transcribed the microstructure on the specimen surface. Although both the DP and Mt. steels exhibited a high tensile strength, the work-hardening rate of the DP steel was higher than that of Mt. steel. Although the numbers of cycles to failure (Nf) in the DP and Mt. steels were almost the same at the total strain amplitudes (εt) of 0.005–0.008 and 0.02–0.03, the Nf in the DP steel was higher than that in the Mt. steel at the εt of 0.008–0.02. The cracks were generated and propagated along the high-tensile-strain regions in both steels and were initiated when the accumulated strain along the loading direction exceeded a critical value regardless of the value of εt or the steel applied. The increment of the accumulated strain in the Mt. steel was higher than that of the DP steel at the εt of 0.01, whereas it was almost the same between those at the εt of 0.03. The inhomogeneity of the strain distribution, which was quantitatively evaluated from the histogram of the strain distribution, increased as the number of fatigue cycles increased. The strain was rather inhomogeneously introduced in the Mt. steel in comparison to the DP steel at the εt of 0.01, whereas almost no difference in the inhomogeneity of the strain distribution was detected between the steels at the εt of 0.03. Thus, the inhomogeneous strain distribution may promote crack initiation and propagation, resulting in a low Nf at the εt of 0.008–0.02 in Mt. steel.

Study on development policy for new cryogenic structural material for superconducting magnet of fusion reactor

Arata Nishimura, Yoshinori Ono, Osamu Umezawa, Susumu Kumagai, Yohko Kato, Tetsuya Kato, Tetsumi Yu … Show more authors

Nuclear Materials and Energy 30 101125 2022.3 [Reviewed]

DOI Web of Science Repository

Language：English Publishing type：Research paper (scientific journal) Publisher：Elsevier Joint Work

The preferential dynamic grain growth mechanism enabling the control of microstructure and texture by high temperature deformation: experimental evidence and applicability

Hiroshi Fukutomi, Kazuto Okayasu, Yusuke Onuki, Makoto Hasegawa, Equo Kobayashi, Bohumir Strnadel, … Show more authors

Materials Transactions 63 ( 2 ) 148 - 156 2022.1 [Reviewed]

DOI Web of Science CiNii Research Repository

Language：English Publishing type：Research paper (scientific journal) Publisher：公益社団法人日本金属学会 Joint Work

The relationship between the mechanism of high temperature deformation and the evolution behavior of microstructure and the texture during deformation, which has been found in various solid solution alloys, is clarified. It is shown that the preferential dynamic grain growth (PDGG) mechanism proposed by the authors can explain the behavior of microstructure change as well as texture change of all studied alloys without contradiction. The essential aspect of the PDGG mechanism is the preferential growth of crystal grains with the orientation stable for deformation and with low Taylor factor in the given deformation mode. It is concluded that the Taylor factor corresponds to dislocation density and stored energy during the high temperature deformation of solid solution alloys when viscous glide of dislocations is the rate controlling process. The possibility of the occurrence of the PDGG mechanism in materials other than solid solution alloys is also discussed.

Crack initiation and propagation behavior in γ’-Fe4N layer during monotonic and cyclic tensile deformation in the nitrided ultra-low carbon steel

Norimitsu Koga, Susumu Saito, Osamu Umezawa

Journal of Materials Science 57 ( 3 ) 2194 - 2207 2022.1 [Reviewed]

DOI Web of Science

Language：English Publishing type：Research paper (scientific journal) Joint Work

Rolling and Sliding Contact Fatigue Process under High Pressure in Carburized SCM420 Steel

Hashimoto Kazuya, Fuchigami Taichi, Yari Keisuke, Umezawa Osamu

Tetsu-to-Hagane 108 ( 1 ) 76 - 87 2022.1 [Reviewed]

DOI Web of Science CiNii Research

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：The Iron and Steel Institute of Japan Joint Work

It is important to improve fatigue life for pitting of gear in order to attempt down-sizing of gear unit and low fuel consumption. Rolling and sliding contact fatigue under high pressure in carburized SCM420 steel is studied. The ultimate aim is to understand the effect of material properties on the fatigue life. In this research, there was considerable interest in change of the material in the contact surface of specimens depending on the shift in tangential force acting on a moving roller in the direction of a tangent to the path of the roller during the fatigue test. Three lubricants were used in these fatigue tests for the purpose of changing the degree of tangential force. A roller tested under a lubricant that the tangential force is shifted higher compared with that of the other lubricant produced a pitting failure earlier. The roller also promoted to decrease the hardness and to narrow the half width of the (211) peak of alpha iron at the contact surface. The transition of these characteristics related to the creation of fine grain layer. That is regarded as worked structure formed during fatigue process. The depth of fine grain layer expands according to repeated loading. Fatigue crack propagation depth was almost equal to the depth of fine grain layer. Not only well-known softening caused by increase in temperature but also microstructural change caused by repeated stress loading have an effect on the life through the involvement in fatigue crack initiation and propagation behavior.

Influence of dispersed β phase on local deformation pattern in mill-annealed Ti-Fe-O alloy under dwell fatigue loading

Yin Liangwei, Umezawa Osamu

International Journal of Fatigue 152 106447 2021.11 [Reviewed]

DOI Web of Science CiNii Research Repository

Authorship：Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：Elsevier Sci Ltd Joint Work

Grain-scale dwell fatigue behavior in Ti-Fe-O alloy is elucidated, with attention focused on the stress redistribution phenomenon that occurs within the soft-hard grain combination. Elastoplastic properties of the beta phase are determined using nanoindentation and crystal plasticity modeling. On this basis, the role of intergranular beta lath on stress redistribution is evaluated. Redistribution of stress from the soft to hard alpha grain is inhibited in the presence of intergranular beta lath during dwell period. Meanwhile, the peak stress in the beta lath is enhanced. This may result in the competition of two dwell fatigue failure modes at high stress state.

Effect of Aging on Low-temperature Tensile Properties of Ultra-low Carbon Steel

Koga Norimitsu, Kanehira Yuki, Huyen Pham Thi Thanh, Hori Kazuya, Umezawa Osamu

ISIJ International 61 ( 8 ) 2308 - 2316 2021.8 [Reviewed]

DOI Web of Science CiNii Research Repository

Language：English Publishing type：Research paper (scientific journal) Publisher：一般社団法人日本鉄鋼協会 Joint Work

The microstructural changes and low-temperature tensile properties of ultra-low carbon steel aged at 443 K were examined, and the relationship between the low-temperature tensile properties and ultra-low carbon state was discussed. Fine cementites of approximately 60 nm were observed at 0.6 ks and coarsened to approximately 800 nm at 600 ks. The yield and tensile stresses at 77 K increased until 6 ks and then decreased. The nominal stress-strain curves of all the specimens at 77 K exhibited low elastic limits, the nominal stress plateaued from an approximate nominal strain of 0.002 and, subsequently, work hardening occurred. In the unaged and 6 ks aged specimens, several twins were generated after the elastic limit, and which increased dramatically in the nominal stress plateau regime, and corresponded to macroscopic yielding. In contrast, the number of twins in the 600 ks aged specimen negligibly increased during macroscopic yielding. Macroscopic yielding occurred in the unaged and 6 ks aged specimens by deformation twinning, while in the 600 ks aged specimen it occurred by slip deformation. In the 6 ks aged specimen, the fine cementites and/or decrease in solid solute carbon enhanced the critical resolved shear stresses of deformation twinning, resulting in the highest strength. In the 600 ks aged specimen, the coarse cementites negligibly enhanced the critical resolved shear stress for slip deformation. Hence, the strength of the specimen aged for 600 ks decreased as compared to the specimen aged for 6 ks, and slip deformation occurred.

Other Link： https://ci.nii.ac.jp/naid/130008075184

Microstructural evolution in Ti-37 mol%Nb alloy under uniaxial compression at high temperatures

Yujiro Hayakawa, Osamu Umezawa

Journal of Alloys and Compounds 871 159603-1 - 159603-11 2021.8 [Reviewed]

DOI Web of Science

Authorship：Corresponding author Language：English Publishing type：Research paper (scientific journal) Joint Work

Spectroscopy analyses of tribofilm and surface microcracks in carburized SCM420 steel under high-pressure rolling contact fatigue

Takayasu Shuto, Umezawa Osamu, Yari Keisuke, Hashimoto Kazuya, Fuchigami Taichi

WEAR 477 203807 2021.7 [Reviewed]

DOI Web of Science CiNii Research Repository

Authorship：Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：Elsevier Science SA Joint Work

The tribofilm and surface microcracks developed on a carburized SCM420 steel through a two-roller-type pitting test were characterized. A streaky 100- to 200-nm-thick tribofilm was generated on the specimen surface after 1.0 x 105 cycles. The tribofilm was identified to be mainly composed of calcium phosphate Ca3(PO4)2 and iron phosphate Fe3(PO4)2. Microcracks having lengths of a few tens of micrometers were detected on the contact surface without the tribofilm after the test. The number of cycles corresponded to a transition of the tangential force between two rollers decreasing to a stick-slip phenomenon as a steady state. A friction modifier additive (molybdenum dialkyldithiocarbamate) was added to a lubricant to improve rolling contact fatigue (RCF) pitting resistance. This lubricant containing the friction modifier additive exhibited a lifetime that was a factor of 10 greater than the RCF lifetime for the lubricant base oil. Therefore, the tribofilm may affect the tangential force and RCF lifetime. The contact surfaces and subsurface structure, especially in the vicinity of the microcracks, were dynamically reconstructed by severe friction and damage accumulation. Oxygen was detected on the surface of the microcracks.

Work hardening behavior of dual phase copper-iron alloy at low temperature

Yamashita Takayuki, Koga Norimitsu, Kawasaki Takuro, Morooka Satoshi, Tomono Shohei, Umezawa Osamu, … Show more authors

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING 819 141509-1 - 141509-10 2021.7 [Reviewed]

DOI Web of Science

Language：English Publishing type：Research paper (scientific journal) Publisher：Elsevier {BV} Joint Work

Heterogeneous strain accumulation in dwell fatigue for a commercially pure titanium hot rolled sheet: crystal plasticity modelling and experiment

Liangwei Yin, Osamu Umezawa

ISIJ International 61 ( 6 ) 1990 - 2001 2021.6 [Reviewed]

DOI Web of Science CiNii Research Repository

Language：English Publishing type：Research paper (scientific journal) Publisher：一般社団法人日本鉄鋼協会 Joint Work

The heterogeneous deformation in a hot-rolled commercially pure titanium grade 1 sheet has been experimentally and numerically investigated under dwell fatigue loading in current paper. The residual strain fields within two regions of interest are probed by digital image correlation (DIC) after interrupted dwell fatigue test. These measurements essentially agree with predictions of a dislocation mechanism-based crystal plasticity model incorporating deformation twinning. The simulated results further indicate that axial strain localization at grain scale mainly derives from prismatic slip activity, followed by pyramidal <a>, basal slip and {1122} compression twinning activities. On this basis, a weighted averaged Schmid factor is proposed to correlate the axial strain accumulation with active plastic deformation modes in individual grains. Besides, the cyclic load shedding within a soft-hard-soft grain pair is captured by crystal plasticity modeling. The stress redistribution from soft to adjacent hard grain implies that the influence of deformation twinning on dwell facet nucleation is limited. The presented study confirms a robust crystal plasticity model and deepens the quantitative analysis of cold dwell fatigue in titanium and its alloys.

Low-temperature tensile properties of Cu-Fe laminated sheets with various number of layers

Koga Norimitsu, Tomono Shohei, Umezawa Osamu

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING 811 141066-1 - 141066-10 2021.4 [Reviewed]

DOI Web of Science

Language：English Publishing type：Research paper (scientific journal) Publisher：Elsevier {BV} Joint Work

Crystallographic orientation in raft-like structure developed by tensile deformation in Cu-Fe alloy sheet

N. Koga, S. Tomono, O. Umezawa

IOP Conference Series: Materials Science and Engineering 1121 ( 012006 ) 2021.4 [Reviewed]

DOI

Language：English Publishing type：Research paper (international conference proceedings) Joint Work

Investigation of ductile fracture mechanism in multipass drawing of hollow specimen

Shiga Akira, Yamashita Tomohiro, Neishi Yutaka, Umezawa Osamu

MATERIALS TRANSACTIONS 62 ( 4 ) 505 - 511 2021.4 [Reviewed]

DOI Web of Science CiNii Research

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：公益社団法人日本金属学会 Joint Work

To apply hollow forming technology for car parts, it is necessary to understand the ductile fracture mechanism of hollow forming. In this study, the cold drawing test and the finite element method analysis (FEM) of hollow specimens were carried out. It was clarified that the ductile fracture of hollow specimens in cold drawing was affected by both stress triaxiality and Lode angle parameter. As a result of fracture observation of a hollow specimen, an equiaxed dimple and an elongated dimple were observed. A mixed-mode ductile fracture mechanism (shear deformation of voids and typical void growth and coalescence) for hollow specimens in cold drawing is assumed. This Paper was Originally Published in Japanese in J. JSTP 61 (2020) 33–39.

Other Link： https://ci.nii.ac.jp/naid/130008002782

Neutron diffraction mapping measurement for Japanese nails in the ancient and present days

Takayuki Yamashita, Stefanus Harjo, Osamu Umezawa, Takuro Kawasaki

JPS Conference Proceedings 33 ( 011063 ) 2021.3 [Reviewed]

DOI

Language：English Publishing type：Research paper (international conference proceedings) Joint Work

Stress partitioning behavior of duplex alloys consisting of BCC and FCC phases at low temperature

Takayuki Yamashita, Shohei Tomono, Satoshi Morooka, Stefanus Harjo, Takuro Kawasaki, Tatsuya Nameki … Show more authors

JPS Conference Proceedings 33 ( 011064 ) 2021.3 [Reviewed]

DOI

Language：English Publishing type：Research paper (international conference proceedings) Joint Work

Influence of microstructure constituents on ductile to brittle transition behavior in multi-phase steel sheets

Hiroyuki Kawata, Osamu Umezawa

ISIJ International 61 ( 3 ) 1002 - 1010 2021.3 [Reviewed]

DOI Web of Science CiNii Research Repository

Language：English Publishing type：Research paper (scientific journal) Publisher：一般社団法人日本鉄鋼協会 Joint Work

The influence of martensite-austenite constituents on the two-step ductile to brittle transition (DBT) behavior of low carbon steel sheets was evaluated using Charpy impact tests with sub-size specimens. Four kinds of steel sheets containing 0–38% volume fraction of MA and polygonal ferrite in the matrix were chosen. Small volumes of MA (i.e., 2 and 14%) revealed a slightly higher transition temperature between the middle shelf (MS) and lower shelf, TML, compared to sheets with 0% MA. Furthermore, the transition temperature between the upper shelf and MS was not affected. The steel sheet containing 38% MA constituents exhibited a normal one-step DBT curve without MS, and a significantly higher transition temperature than the steel sheets containing 0, 2, and 14% MA. The increase in the austenite volume fraction in MA from 0.6 to 10.2% was not responsible for the DBT behavior, which may depend on the volume fraction of martensite in MA. A model of two-step DBT for multi-phase steel sheets, in which the small volume of MA lowered the fracture stress of the hard structure and elevated TML, was proposed. The TML depended on the intersection between the fracture stress of the hard structure and the yield stress of the soft structure. In the two-step DBT, the cleavage crack propagation was arrested at ferrite grain boundaries through the MS. A large volume of MA (e.g., all the ferrite grains fully covered) may promote one-step DBT in multi-phase steel sheets, owing to cleavage crack propagation.

Influence of layer thickness on tensile deformation and fracture in ferrite + martensite fine multi-layered steel sheets

Norimitsu Koga, Masayuki Suzuki, Osamu Umezawa

Materials Science and Engineering A 806 140599-1 - 140599-9 2021.3 [Reviewed]

DOI Web of Science

Language：English Publishing type：Research paper (scientific journal) Publisher：Elsevier Joint Work

Effect of solute carbon on the characteristic hardening of steel at high temperature

Norimitsu Koga, Osamu Umezawa, Masayuki Yamamoto, Takashi Yamamoto, Takayuki Yamashita, Satoshi Mor … Show more authors

Metallurgical and Materials Transactions A 52 ( 3 ) 897 - 901 2021.3 [Reviewed]

DOI Web of Science

Language：English Publishing type：Research paper (scientific journal) Publisher：Springer Joint Work

Equiaxed α microstructure evolution in wrought Ti-10Al-1Zr-1Mo-1Nb alloy during annealing

Shintaro Tanii, Osamu Umezawa, Yoko Yamabe-Mitarai

Journal of Alloys and Compounds 854 157184-1 - 157184-13 2021.2 [Reviewed]

DOI Web of Science Repository

Authorship：Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：Elsevier Joint Work

Tensile properties and deformation behavior of ferrite and austenite duplex stainless steel at cryogenic temperatures

Norimitsu Koga, Tatsuya Nameki, Osamu Umezawa, Valentin Tschan, Klaus-Peter Weiss

Materials Science and Engineering A 801 140442-1 - 140442-8 2021.1 [Reviewed]

DOI Web of Science CiNii Research Repository

Language：English Publishing type：Research paper (scientific journal) Publisher：Elsevier Joint Work

The tensile properties and deformation and fracture behaviors of a commercial ferrite (body-centered cubic) and austenite (face-centered cubic) duplex stainless steel were investigated at cryogenic temperatures, and the mechanism underlying the improvement in the tensile properties of the steel at cryogenic temperatures was discussed. The strength of the steel increased continuously with lowering temperature, and the elongation hardly decreased with a decrease in temperature from 293 K to 77 K. At 40 K, the elongation of the steel decreased drastically, however, it increased significantly at 8 K. The serration of the steel was measured during its tensile test at 8 K. The volume fraction of the deformation induced martensite was high at 77 K and 8 K, while it was low at 40 K. The strain accumulated in the ferrite and austenite phases during the deformation process remained almost constant at all the test temperatures. The ductile fracture occurred 293 K, 200 K, 77 K, and 8 K, while brittle fracture occurred at 40 K. The low volume fraction of the deformation induced martensite and the occurrence of brittle fracture can explain the low elongation of the steel at 40 K. At 8 K, the occurrence of serration may increase the temperature in the deformation region, which led to an increase in the volume fraction of the deformation induced martensite, as well as the suppression of brittle fracture, resulting in high elongation. The occurrence of deformation induced martensitic transformation, simultaneous deformation of ferrite and austenite, ductile fracture contribute to improvement of tensile property of ferrite and austenite duplex stainless steel at cryogenic temperatures.

Microstructure and low temperature tensile properties in Cu–50 mass%Fe alloy

Koga Norimitsu, Zhang Weisi, Tomono Shohei, Umezawa Osamu

MATERIALS TRANSACTIONS 62 ( 1 ) 57 - 61 2021.1 [Reviewed]

DOI CiNii Research

Language：English Publishing type：Research paper (scientific journal) Publisher：公益社団法人日本金属学会 Joint Work

The temperature dependence of the mechanical properties of metals is closely related to its crystal structure. In bcc metals, the strength of the material increases with decreasing temperature, and the ductility decreases drastically at low temperatures. The mechanical properties of fcc metals hardly depend on temperature, and thus fcc metals exhibit large elongations even at low temperatures. In this study, the microstructure and low-temperature tensile properties of Cu–50 mass%Fe alloy consisting of fcc (Cu) and bcc (Fe) dual-phase structures were investigated. The Cu and Fe layers were aligned along the rolling direction. The deformation structures remained after annealing at 1023 K for 1.8 ks, while recrystallized ultra-fine grains were formed after annealing at 1123 K for 1.8 ks. At both annealing temperatures, Cu and Fe precipitated in the Fe and Cu layers, respectively. The elongation obtained when the alloy was annealed at 1123 K for 1.8 ks was higher than that at 1023 K for 1.8 ks. The recovery of strain and the formation of ultra-fine grain during annealing at 1123 K were largely responsible for the higher elongation. The tensile strength at 77 K was higher than that at 293 K for both annealing temperatures. Nevertheless, the elongation at 77 K was approximately equal to that at 293 K. Therefore, the fcc and bcc dual-phase structures has an excellent temperature dependence of mechanical properties: high strength in bcc structure and high elongation in fcc structure at low temperatures. A dimple fracture surface appeared at 77 K, indicating that ductile fracture occurred in both phases. Therefore, the Fe phase exhibited significant ductility even at 77 K. The excellent low-temperature tensile properties of the Cu–Fe dual-phase alloy may be due to strengthening by the Fe phase and suppressing of brittle fracture in the Fe phase by the ductile Cu phase. This Paper was Originally Published in Japanese in J. Japan Inst. Copper 59 (2020) 289–293. All captions are slightly changed.

Other Link： https://ci.nii.ac.jp/naid/130007947225

Effect of the Laves phase and carbide on the creep strength of Fe–C–15Cr–W alloys

Yoshiaki Toda, Yuki Nakamura, Naomichi Harada, Akihiro Kaseya, Nina Kobata, Yoko Yamabe-Mitarai, Os … Show more authors

Materials Science and Engineering A 797 140104-1 - 140104-9 2020.10 [Reviewed]

DOI Web of Science

Language：English Publishing type：Research paper (scientific journal) Publisher：Elsevier Joint Work

Equiaxed α microstructure evolution in wrought Ti-10Al-1Zr-1Mo-1Nb alloy during annealing

Tanii Shintaro, Umezawa Osamu, Yamabe-Mitarai Yoko

Journal of alloys and compounds 854 157184 2020.10 [Reviewed]

CiNii Research

Authorship：Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：Elsevier Joint Work

Evolution of α microstructure on the thermomechanical treated Ti-10Al-1Zr-1Mo-1Nb alloy during annealing was studied. The solution-treated materials were groove-rolled or uniaxially compressed in the α+β region and annealed at 1173 K. The flow softening behavior and crystal rotation in α platelets revealed an evolution of deformation texture. The volume fraction of equiaxed α grains was increased during annealing. Especially in the material compressed at a strain rate of 1 s−1, the equiaxed α grains developed within a shorter annealing duration than 1.8 ks. The deformation with higher strain rates promoted the division and fragmentation of α platelets during annealing. Transmission electron microscopy and X-ray diffraction analyses were employed to characterize dislocation components and structure, where the installed screw dislocations provided a fine substructure and high energy α/α boundaries in α platelets. The triple junction consisting of α/β boundaries and α/α boundaries may provide a site for thermal grooving, which induces the division and fragmentation of α platelets. Therefore, deformation at a higher strain rate is necessary in α+β processing to develop a fine equiaxed α microstructure for the Ti-10Al-1Zr-1Mo-1Nb alloy during annealing.

Microstructural evolution in Ti-10Al-1Zr-1Mo-1Nb alloy under thermomechanical treatment in the β-region

Shintaro Tanii, Osamu Umezawa, Yoko Yamabe-Mitarai

Materials Science and Engineering A 796 140149-1 - 140149-10 2020.10 [Reviewed]

DOI Web of Science Repository

Authorship：Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：Elsevier Joint Work

Strain distribution and deformation-induced martensitic transformation in tension for a TRIP steel plate

Koga Norimitsu, Yamashita Takayuki, Umezawa Osamu

ISIJ International 60 ( 9 ) 2083 - 2089 2020.9 [Reviewed]

DOI Web of Science CiNii Research Repository

Language：English Publishing type：Research paper (scientific journal) Publisher：一般社団法人日本鉄鋼協会 Joint Work

Digital image correlation was applied to analyze the strain distribution and deformation-induced martensitic transformation of retained austenite in a low alloy transformation-induced plasticity (TRIP) steel plate under tension. The distribution of strain instilled by tensile deformation was inhomogeneous at a microscopic scale. Strain generated by deformation-induced martensitic transformation was successfully visualized and it led to a homogeneous strain distribution. The retained austenite in the high strain region transformed to martensite preferentially, which demonstrates that inhomogeneous strain distribution affects the stability of retained austenite. The high resolution strain distribution exhibited that a certain amount of strain instilled into retained austenites and there are a lot of strain concentration sites at ferrite/austenite interfacial boundaries in high strain region. Therefore, the stress concentration at the ferrite/retained austenite interfacial boundary occurs due to the difference of strain between the ferrite matrix and retained austenite. These strain accumulation in a retained austenite and/or stress concentration at ferrite/retained austenite interfacial boundary may induce martensitic transformation in high strain regions.

Other Link： https://ci.nii.ac.jp/naid/130007833003

Microstructural evolution in Ti–10Al–1Zr–1Mo–1Nb alloy under thermomechanical treatment in β-region

Tanii Shintaro, Umezawa Osamu, Yamabe-Mitarai Yoko

Materials Science and Engineering: A 796 2020.9 [Reviewed]

CiNii Research

Authorship：Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：Elsevier Joint Work

The influence of temperature and strain rate on microstructural evolution in near α-type Ti–10Al–1Zr–1Mo–1Nb alloy was studied under uniaxial compression in the β single-phase-region. Hot compression tests were conducted for up to 75% reduction at temperatures between 1273 K and 1333 K and strain rates between 0.01 s^−1 and 5 s^−1. The steady-state of the flow behavior revealed that dynamic recovery in the β single-phase was dominant in the microstructural evolution process, and few dynamically recrystallized grains were detected, except in the vicinity of the pre-existing β grain boundaries. Two types of configurations such as lamellar α_L and acicular α_AC microstructures were developed, which were consistent with the compressive deformation mechanism in the β-region. The α_L microstructure consisted of α platelets that were developed via growth of a specific variant, whereas the α_AC microstructure consisted of individual α platelets with a different variant in the prior-β matrix. The stress exponent and activation energy were evaluated to determine the deformation mechanism. The heterogeneous nucleation of individual α platelets in the cellular structure (sub-grains) without a specific orientation in the β matrix resulted in the αAC microstructure. In contrast, the substructure as uniformly distributed dislocations in prior-β grains under the viscous motion of dislocations promoted a single variant selection to form αL platelets in the transformation. When the viscous drag dislocation motion in the β-region is dominant, a large crystal rotation is detected in the acicular (side plate) α_SP platelets in the vicinity of the prior-β grain boundary.

Tensile deformation of texture-controlled titanium with high oxygen content at room temperature

Motoaki Morita, Shogo Suzuki, Yaku Kato, Weibo Li, Osamu Umezawa

Materials Science and Engineering A 793 139660-1 - 139660-14 2020.8 [Reviewed]

DOI Web of Science

Language：English Publishing type：Research paper (scientific journal) Joint Work

Cu-50mass％Fe二相合金の組織と低温引張特性

古賀紀光, 張偉思, 友野翔平, 梅澤修

銅と銅合金 59 ( 1 ) 289 - 293 2020.8 [Reviewed]

DOI CiNii Research

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：日本銅学会 Joint Work

The temperature dependence on mechanical properties in a metal material relates to its crystal structure. In a bcc metal, the strength increases with lowering temperature though the ductility decreases drastically at a low temperature. While mechanical properties in an fcc metal hardly depend on temperature, and thus the fcc metal exhibits high elongation even at low temperatures. In this study, the microstructure and low temperature tensile properties in Cu–50mass％Fe alloy consisting of fcc （Cu） and bcc （Fe） dual phase structure were investigated. Cu and Fe layers were aligned along the rolling direction. The microstructure after annealing at 1023 K for 1.8 ks maintained a deformation structure, while it after annealing at 1123 K for 1.8 ks was the recrystallized ultra–fine grain. In both annealing temperature, Cu and Fe precipitated in Fe and Cu layers, respectively. The elongation in the specimen annealing at 1123 K for 1.8 ks was higher than that of the specimen annealing at 1023 K for 1.8 ks. The recovery of strain and ultra–fine grains should improve the elongation in the specimen annealing at 1123 K. The tensile strength at 77 K was higher than that at 293 K in both specimens annealing at 1023 K and 1123 K. Nevertheless, the elongation at 77 K was nearly equivalent to that at 293 K. Therefore, the fcc and bcc dual phase structure has a superior temperature dependence on mechanical properties： high strength in bcc structure and high elongation in fcc structure at low temperature. A dimple fracture surface appeared at 77 K, meaning that the ductile fracture occurs in both phases. Hence, the Fe phase has enough ductility even at 77 K. The superior low temperature tensile properties may be due to strengthening by the Fe phase and suppressing brittle fracture of the Fe phase by the ductile Cu phase.

Other Link： https://ci.nii.ac.jp/naid/130007940921

Role of retained austenite in low alloy steel at low temperature monitored by neutron diffraction

Yamashita Takayuki, Morooka Satoshi, Harjo Stefanus, Kawasaki Takuro, Koga Norimitsu, Umezawa Osamu

SCRIPTA MATERIALIA 177 6 - 10 2020.3 [Reviewed]

DOI Web of Science CiNii Research Repository

Language：English Publishing type：Research paper (scientific journal) Publisher：Elsevier Ltd Joint Work

In-situ neutron diffraction measurements during tensile tests at low temperatures of a low alloy steel containing retained austenite (γ) have been performed. Evolutions of phase fractions and phase stresses were analyzed and discussed with the progress of deformation. The role of γ in the steel during deformation at low temperatures was observed not to directly in the contribution to the strengths but in the improvement of the elongation by transformation of γ to martensite -and in the increasing of the work-hardening rate by an increase in the phase fraction of martensite and the work hardening of martensite.

<111> 優先配向したアルミニウム矩形引抜線材の繰返し曲げ変形

池谷隼人，梅澤修，福富洋志

軽金属 70 ( 2 ) 51 - 55 2020.2 [Reviewed]

DOI

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：一般社団法人軽金属学会 Joint Work

Investigation of Ductile Fracture Mechanism in Multipass Drawing of Hollow Specimen

SHIGA Akira, YAMASHITA Tomohiro, NEISHI Yutaka, UMEZAWA Osamu

Journal of the Japan Society for Technology of Plasticity 61 ( 709 ) 33 - 39 2020.2 [Reviewed]

DOI CiNii Research

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：The Japan Society for Technology of Plasticity Joint Work

Other Link： https://ci.nii.ac.jp/naid/130007801667

Effects of surface compound layer on bending fatigue strength of nitrided chromium molybdenum steel

Tsuyoshi Kubota, Osamu Umezawa

SAE International Journal of Advances and Current Practices in Mobility 2 ( 2 ) 979 - 984 2020.1 [Reviewed]

Language：English Publishing type：Research paper (scientific journal) Joint Work

Modeling of surface crack defects developed on shear edge in high-strength automotive steel sheets

Goto Sota, Yamazaki Kazuhiko, Doan Thi-Huyen, Funakawa Yoshimasa, Umezawa Osamu

ISIJ International 60 ( 1 ) 143 - 152 2020.1 [Reviewed]

DOI Web of Science CiNii Research Repository

Language：English Publishing type：Research paper (scientific journal) Publisher：一般社団法人日本鉄鋼協会 Joint Work

Surface crack defects developed on the shear edge cause a problem in shearing of high-strength steels. The surface crack formation mechanism was clarified by microstructural examinations and numerical simulation. Two types of 780 MPa grade hot-rolled steel sheets with a thickness of 2.6 mm were chosen for the evaluations because the materials show different surface crack susceptibilities. Cleavage fracture was responsible for the surface cracks, and micro-ductile cracks with a length of 30 µm to 40 µm were detected in the interrupted punching samples. A numerical simulation demonstrated that a tensile stress was developed in the direction of the micro-ductile cracks opening during punching process. The critical length of the micro-ductile crack for cleavage fracture as a crack initiation site was given by linear fracture mechanics; for example, the critical length is 23 µm or longer under the applied tensile stress of 910 MPa. The tensile stress causing cleavage fracture decreased by reducing the tool clearances, and it was shown experimentally that surface crack defects can be prevented by controlling the clearance appropriately.

Other Link： https://ci.nii.ac.jp/naid/130007786265

Mechanism of Texture and Microstructure Evolution during High Temperature Plane Strain Compression in AZ31B and AZ80 Magnesium Alloys with Various Initial Textures

Fukutomi Hiroshi, Park Hyung-Gyun, Kim Kwon-Hoo, Okayasu Kazuto, Hasegawa Makoto, Umezawa Osamu

Journal of the Japan Institute of Metals and Materials 83 ( 8 ) 264 - 272 2019.8 [Reviewed]

DOI Web of Science CiNii Research

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：The Japan Institute of Metals and Materials Joint Work

The effects of pre-existent textures on the evolution behaviors of microstructure and texture at high-temperature plane strain compression deformation of AZ31B magnesium alloy have been studied. Deformation is conducted at 723 K with a strain rate of 5.0 × 10−2 s−1, up to −1.3 in true strain. When non-basal slip systems are the primary slip systems, {1120}<1010> texture develops. In this case, repeated change in microstructure and texture which was found in the previous work appeared with increasing strain. Namely, replacement of {1120}<1010> texture with {1010}<1120> texture and the reverse phenomenon occurs. While the {1120}<1010> oriented grains are small and with wavy shaped grain boundaries, the {1010}<1120> oriented grains are large and with rather straight grain boundaries. The mechanism of repeated change in microstructure and texture is discussed on the basis of preferential dynamic grain growth mechanism proposed by the authors.

Other Link： https://ci.nii.ac.jp/naid/130007683520

Effect of pearlite volume fraction on two-step ductile to brittle transition in ferrite + pearlite structure steel sheets

Hiroyuki Kawata, Osamu Umezawa

ISIJ International 59 ( 7 ) 1344 - 1353 2019.7 [Reviewed]

DOI CiNii Research

Language：English Publishing type：Research paper (scientific journal) Publisher：一般社団法人日本鉄鋼協会 Joint Work

Multi structural steels exhibit high strength and good formability; however, their performance depends on the volume fraction of the secondary phase. In our previous study, ferrite + pearlite structural steel sheet showed the characteristic two-step ductile-to-brittle transition (DBT) with decreasing temperature, and the absorbed energy curve exhibited a distinct middle shelf. In this study, we evaluated the effect of pearlite volume fraction (VP) on the DBT behavior by the Charpy impact test with sub-size specimens. For specimens without pearlite, the absorbed energy directly dropped from the upper shelf to the lower shelf with decreasing temperature. For samples with 2–3% pearlite, the absorbed energy corresponding to the transition temperature range was dispersed between the two shelves, and the transition behavior seemed to be the typical DBT behavior. When VP was increased to 21%, the absorbed energy just above the transition-finish temperature became stable at a middle level between the two shelves; thus, the existence of a distinct middle shelf was confirmed. Although the transition-start temperature increased with increasing VP, VP did not affect the transition-finish temperature and the absorbed energy at the middle shelf. These results were analyzed with a simple model based on the Yoffee diagram.

Other Link： https://ci.nii.ac.jp/naid/130007679258

Crystal orientation analysis on stress corrosion cracking facets in austenitic stainless steels

Ryo Wakinaga, Norimitsu Koga, Osamu Umezawa, Motoaki Morita, Shinichi Motoda, Tadashi Shinohara

Key Engineering Materials 810 64 - 69 2019.7 [Reviewed] [Invited]

DOI

Language：English Publishing type：Research paper (international conference proceedings) Joint Work

Crystal lattice rotation and fatigue crack generation in aluminum wire under cyclic bending deformation

Ikeya Hayato, Umezawa Osamu, Fukutomi Hiroshi

Journal of Japan Institute of Light Metals 69 ( 6 ) 302 - 308 2019.6 [Reviewed]

DOI CiNii Research

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：The Japan Institute of Light Metals Joint Work

The relationship between the grain boundary steps on the specimen surface developed by cyclic bending and fatigue crack generation on the grain boundaries inclined at about 45 degree to the principal stress axis has been discussed for 4N-aluminum wire. The crystal lattice rotation near the grain boundary induced by slip bands in a grain resulted in a strain incompatibility with the neighboring grain. Due to the shear deformation along the grain boundary, the individual grain boundary steps coalesce and form a grain boundary microcrack, resulting in the fatigue crack generation and propagation. The strain incompatibility is developed at the grain boundary between the grain accompanied with crystal rotation over 10 degrees in the vicinity of the boundary and the grain with almost no crystal rotation. Based on the approximation that only the primary slip system is operative, the step height due to the crystal slip deformation is estimated from the lattice rotation near the grain boundary.

Other Link： https://ci.nii.ac.jp/naid/130007684576

IMPROVEMENT IN CREEP AND STEAM OXIDATION RESISTANCE OF PRECIPITATION STRENGTHENED FERRITIC STEELS

Toda Yoshiaki, Yoko Yamabe-Mitarai, Akihiko Kaseya, Umezawa Osamu

JOINT EPRI - 123HIMAT INTERNATIONAL CONFERENCE ON ADVANCES IN HIGH-TEMPERATURE MATERIALS, 2019 96 - 103 2019

Web of Science

Language：Japanese Publishing type：Research paper (international conference proceedings) Joint Work

A Subsurface fatigue crack generation model in near alpha titanium at low temperature

Osamu Umezawa, Weibo Li

Materials Science Forum 941 1336 - 1341 2018.12 [Reviewed] [Invited]

DOI

Language：English Publishing type：Research paper (international conference proceedings) Publisher：Trans Tech Publications Joint Work

Middle shelf during ductile to brittle transition on ferrite + pearlite structural steel sheet

Hiroyuki Kawata, Osamu Umezawa

Materials Science Forum 941 453 - 457 2018.12 [Reviewed]

DOI

Language：English Publishing type：Research paper (international conference proceedings) Publisher：Trans Tech Publications Joint Work

Visualization of strain distribution in tensile test of ferrite + martensite multilayered steel sheet by digital image correlation method

Norimitsu Koga,Masayuki Suzuki,Osamu Umezawa

Procedia Manufacturing 15 1656 - 1662 2018.9 [Reviewed]

DOI

Language：English Publishing type：Research paper (scientific journal) Joint Work

Detection of surface roughness evolution of carbon steel subjected to outdoor exposure test and constant humidity corrosion tests

Dara To, Osamu Umezawa, Tadashi Shinohara

Materials Transactions 59 ( 8 ) 1239 - 1243 2018.8 [Reviewed]

DOI

Language：English Publishing type：Research paper (scientific journal) Joint Work

Fractographical analyses of crack initiation site in high-cycle fatigue for Ti-Fe-O alloy at low temperature

Osamu Umezawa, Takayuki Yuasa, Weibo Li

ISIJ International 58 ( 7 ) 1332 - 1340 2018.7 [Reviewed]

DOI

Language：English Publishing type：Research paper (scientific journal) Joint Work

Influence of deformability of retained austenite on martensitic transformation in tension for low alloy steel at low temperatures

Takayuki Yamashita, Norimitsu Koga, Osamu Umezawa

ISIJ International 58 ( 6 ) 1155 - 1161 2018.6 [Reviewed]

DOI

Language：English Publishing type：Research paper (scientific journal) Joint Work

微細組織から見たアルミニウム線材の繰返し曲げ変形と破壊挙動

池谷隼人，梅澤修，福富洋志

軽金属 68 ( 5 ) 243 - 249 2018.5 [Reviewed]

Language：Japanese Publishing type：Research paper (scientific journal) Joint Work

Martensitic transformation of retained austenite in ferrite matrix for low alloy steel

Takayuki Yamashita, Norimitsu Koga, Osamu Umezawa

Materials Tranactions 59 ( 5 ) 712 - 716 2018.5 [Reviewed]

DOI

Language：English Publishing type：Research paper (scientific journal) Joint Work

Analysis of subsurface fatigue crack generation in Ti-Fe-O alloy at low temperature

Weibo Li, Osamu Umezawa, Norimitsu Koga

ISIJ International 58 ( 2 ) 359 - 363 2018.2 [Reviewed]

DOI Web of Science

Language：English Publishing type：Research paper (scientific journal) Publisher：IRON STEEL INST JAPAN KEIDANREN KAIKAN Joint Work

Crystallographic characterization of the middle shelf in a two-step ductile to brittle transition for a ferrite + pearlite structure steel sheet

Hiroyuki Kawata, Osamu Umezawa

Materials Science and Engineering A 716 252 - 259 2018.2 [Reviewed]

DOI Web of Science

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER Joint Work

Temperature dependence on tensile properties of Cu-40mass%Fe dual phase alloy

Norimitsu Koga, Weisi Zhang, Osamu Umezawa, Valentin Tschan, Jan Sas, Klaus-Peter Weiss

IOP Conference Series: Materials Science and Engineering 279 012004 2018.1 [Reviewed]

DOI Web of Science

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IOP PUBLISHING LTD Joint Work

Two step ductile to brittle transition behavior on ferrite + pearlite structure steel sheet

Hiroyuki Kawata, Osamu Umezawa

ISIJ International 57 ( 7 ) 1282 - 1288 2017.7 [Reviewed]

DOI Web of Science CiNii Research J-GLOBAL

Language：English Publishing type：Research paper (scientific journal) Publisher：Iron and Steel Institute of Japan Joint Work

Other Link： https://www.jstage.jst.go.jp/article/isijinternational/57/7/57_ISIJINT-2017-026/_article

Effects of slip ratio on damage and microcracks in carburized SCM420 steel under rolling contact fatigue

Junichi Sanekata, Norimitsu Koga, Osamu Umezawa

Key Engineering Materials 741 94 - 98 2017.6 [Reviewed] [Invited]

DOI

Language：English Publishing type：Research paper (international conference proceedings) Joint Work

Mechanical stability and deformation-induced transformation of retained austenite in TRIP steels at low temperature

Takayuki Yamashita, Norimitsu Koga, Osamu Umezawa

Key Engineering Materials 741 36 - 41 2017.6 [Reviewed] [Invited]

DOI

Language：English Publishing type：Research paper (international conference proceedings) Joint Work

Effect of Si content on fatigue fracture behavior of hot-rolled high-silicon steels

Osamu Umezawa, Jyunichi Kanda and Takao Yamazaki

Journal of Physics 843 ( 1 ) 012046 2017.5 [Reviewed]

DOI Web of Science

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IOP PUBLISHING LTD Joint Work

A study on the initial atmospheric corrosion behaviors of carbon steel exposed to urban and marine atmosphere in Cambodia

Dara To, Tadashi Shinohara, Osamu Umezawa

ZAIRYO-TO-KANKYO 66 ( 4 ) 131 - 135 2017.4 [Reviewed]

DOI

Language：English Publishing type：Research paper (scientific journal) Joint Work

Effect of Phase in Surface Compound Layer on Rotating Bending Fatigue Strength for Gas-nitrided SCM435 Steel

HIRAOKA Yasushi,ISHIDA Akihiro,UMEZAWA Osamu

Journal of the Japan Society for Heat Treatment 57 ( 2 ) 64 - 72 2017.4 [Reviewed]

DOI CiNii Research J-GLOBAL

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：The Japan Society for Heat Treatment Joint Work

Other Link： https://www.jstage.jst.go.jp/article/netsushori/57/2/57_64/_article/-char/ja/

Development of artificial rainfall equipment for studying the effect of rain on the corrosion behaviors

Dara To, Tadashi Shinohara, Osamu Umezawa

ZAIRYO-TO-KANKYO 66 ( 2 ) 58 - 61 2017.2 [Reviewed]

DOI CiNii Research J-GLOBAL

Language：English Publishing type：Research paper (scientific journal) Publisher：Japan Society of Corrosion Engineering Joint Work

Other Link： https://www.jstage.jst.go.jp/article/jcorr/66/2/66_58/_article

Effects of cross-rolling on deformation texture evolution in unalloyed titanium

Osamu Umezawa, Norimitsu Koga

Materials Science Forum 879 2014 - 2019 2017.2 [Reviewed]

DOI

Language：English Publishing type：Research paper (scientific journal) Publisher：Trans Tech Publications, Joint Work

Effect of Ions Eluted from Metal Surface on Transformation and Growth of Calcium Carbonate Polymorphisms

HASHIMOTO Ryohei,MORITA Motoaki,UMEZAWA Osamu,Motoda Shinichi

Journal of Japan Institute of Meals and Materials 81 ( 2 ) 89 - 96 2017.2 [Reviewed]

DOI CiNii Research J-GLOBAL

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：The Japan Institute of Meals and Materials Joint Work

Other Link： https://www.jstage.jst.go.jp/article/jinstmet/81/2/81_J2016045/_article/-char/ja/

Experimental investigation on the corrosivity of atmosphere through the atmospheric corrosion monitoring (ACM) sensors

Dara To, Tadashi Shinohara, Osamu Umezawa

ECS Transactions 75 ( 29 ) 1 - 10 2017.1 [Reviewed]

DOI

Language：English Publishing type：Research paper (scientific journal) Joint Work

A model of scale formation on inner carbon steel pipe walls for transporting hot spring water

M. Morita, O. Umezawa

Materials Transactions 57 ( 9 ) 1652 - 1659 2016.9 [Reviewed]

DOI Web of Science

Language：English Publishing type：Research paper (scientific journal) Publisher：JAPAN INST METALS Joint Work

Effects of anion on the corrosion behaviors of carbon steel under artificial rainfall

Dara To, Tadashi Shinohara and Osamu Umezawa

The Ninth Pacific Rim International Conference on Advanced Materials and Processing 276 - 281 2016.8 [Reviewed]

Language：English Publishing type：Research paper (international conference proceedings) Publisher：The Japan Institute of Metals and Materials Joint Work

Effects of anion on the corrosion behaviors of carbon steel under artificial experiment

Dara To, Tadashi Shinohara, Osamu Umezawa

International Journal of Research in Engineering and Technology 5 ( 8 ) 382 - 387 2016.8 [Reviewed]

Language：English Publishing type：Research paper (scientific journal) Joint Work

Effects of α-grain structure on cyclic deformation structure of Ti-Fe-O alloy at low temperature

Weibo Li, Osamu Umezawa

Proceedings of the 13th World Conference on Titanium 843 - 847 2016.7 [Reviewed]

DOI

Language：English Publishing type：Research paper (international conference proceedings) Publisher：John Wiley & Sons, Inc. Joint Work

Evaluation of fatigue crack growth in α-titanium alloys

O. Umezawa, M. Hamada, T. Tatsumi

Procedia Materials Science 12 48 - 53 2016.5 [Reviewed] [Invited]

DOI

Language：English Publishing type：Research paper (scientific journal) Joint Work

A Model of Scale Formation Process to Inner Wall of Carbon Steel Pipe for Transporting Hot Spring Water

MORITA Motoaki,UMEZAWA Osamu

Journal of Japan Institute of Meals and Materials 80 ( 5 ) 309 - 316 2016.5 [Reviewed]

DOI CiNii Research J-GLOBAL

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：The Japan Institute of Meals and Materials Joint Work

Other Link： https://www.jstage.jst.go.jp/article/jinstmet/80/5/80_J2015051/_article/-char/ja/

Effect of Nitriding Temperature and Compositions on Diffusion Layer's Hardness in Gas Nitrided Low Alloy Steel Containing Chromium

HIRAOKA Yasushi,WATANABE Youichi,UMEZAWA Osamu

Journal of Japan Institute of Meals and Materials 80 ( 4 ) 253 - 258 2016.4 [Reviewed]

DOI CiNii Research J-GLOBAL

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：The Japan Institute of Meals and Materials Joint Work

Other Link： https://www.jstage.jst.go.jp/article/jinstmet/80/4/80_J2015066/_article/-char/ja/

Practical Model to Predict Diffusion Layer's Hardness Profile in Gas Nitrided Low Alloy Steel Containing Chromium

HIRAOKA Yasushi,WATANABE Youichi,UMEZAWA Osamu

Journal of Japan Institute of Meals and Materials 80 ( 4 ) 259 - 267 2016.4 [Reviewed]

DOI CiNii Research J-GLOBAL

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：The Japan Institute of Meals and Materials Joint Work

Other Link： https://www.jstage.jst.go.jp/article/jinstmet/80/4/80_J2015067/_article/-char/ja/

Tensile properties and conductivities of a precipitation hardened and cold-rolled Cu-0.3Cr-0.1Zr alloy at cryogenic temperature

Osamu Umezawa

IOP Conference Series: Materials Science and Engineering 102 012006 2015.12 [Reviewed]

DOI Web of Science

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IOP PUBLISHING LTD Single Work

Effect of Carbon Content on Phase Stabilities ofγand εin Compound Layer During Gas Nitriding for Low Alloy Steel

HIRAOKA Yasushi,WATANABE Youichi,UMEZAWA Osamu

Journal of the Japan Society for Heat Treatment 54 ( 6 ) 313 - 318 2014.12 [Reviewed]

DOI CiNii Research J-GLOBAL

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：The Japan Society for Heat Treatment Joint Work

Other Link： https://www.jstage.jst.go.jp/article/netsushori/54/6/54_313/_article/-char/ja/

New aspects of ecomaterials from viewpoints of consumer and regional community

Osamu Umezawa, Yoshikazu Shinohara, Kohmei Halada

Materials Transactions 55 ( 5 ) 745 - 749 2014.5 [Reviewed]

DOI Web of Science

Language：English Publishing type：Research paper (scientific journal) Publisher：JAPAN INST METALS Joint Work

Practical model to predict nitrogen-diffusion layer's hardness in gas nitrided chromium-containing steel

Yasushi Hiraoka, Youichi Watanabe, Osamu Umezawa

Proceedings of European Conference on Heat Treatment and 21st IFHTSE Congress 119 - 126 2014.5 [Reviewed]

Language：English Publishing type：Research paper (international conference proceedings) Publisher：Arbeitsgemeineschaft Warmebehandlung u. Werkstofftechnik Joint Work

局部加圧によるADC12ダイカストの疲労強度向上

井澤龍介, 梅澤　修, 桑田　浩

鋳造工学 86 ( 4 ) 294 - 300 2014.4 [Reviewed]

DOI

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：日本鋳造工学会 Joint Work

ADC12アルミニウムダイカストの肉厚部に局所加圧を施し、平面曲げ疲労試験における疲労強度下限値の向上を得た。この主要因は、内部欠陥サイズや数密度の低減であることを示し、欠陥サイズと疲労強度との関係を定量的に評価し、局所加圧による凝固直後の高温加工が基地に与える影響を示した。

Lattice parameters and relative stability of α" phase in binary titanium alloys from first-principles calculations

Chun-Xia Li, Hu-Bin Luo, Qing-Miao Hu, Rui Yang, Fu-Xing Yin, Osamu Umezawa, Levente Vitos

Solid State Communications 159 70 - 75 2013.5 [Reviewed]

DOI Web of Science

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER Joint Work

微粒子ピーニングによるアルミダイカスト材の疲労強度向上

井澤龍介, 梅澤　修, 中村紀夫，高木眞一

鋳造工学 85 ( 3 ) 155 - 160 2013.3 [Reviewed]

Language：Japanese Publishing type：Research paper (scientific journal) Joint Work

ADC12アルミニウムダイカスト部品の表面に微粒子ピーニング処理を施し、約5μmの表面改質皮膜の形成や深さ100μm以上にわたる残留圧縮応力の導入により、両振り疲労試験において約50%の疲労強度向上を得た。また、試料表面のマクロ欠陥を塞ぐ効果を確認し、マクロ欠陥を有するダイカスト部品の局所的な疲労特性強化に有効であることを示した。

Subsurface crack generation and flacking under rolling contact fatigue

O. Umezawa, S. Morooka, J. Brumek

th Inter. Workshop on New Method of Damage and Failure Analysis of Structural Parts 421 - 427 2012.9 [Reviewed]

Language：English Publishing type：Research paper (international conference proceedings) Joint Work

In-situ neutron diffraction study on tensile deformation behavior of steels

S. Morooka, H.Kawata, S.Harjo, O. Umezawa

5th Inter. Workshop on New Method of Damage and Failure Analysis of Structural Parts 369 - 375 2012.9 [Reviewed]

Language：English Publishing type：Research paper (international conference proceedings) Joint Work

Fatigue behavior at punched hole in high strength hot-rolled steels

K. Nakajima, Y. Funakawa, D. Tajiri, O. Umezawa

5th Inter. Workshop on New Method of Damage and Failure Analysis of Structural Parts 87 - 92 2012.9 [Reviewed]

Language：English Publishing type：Research paper (international conference proceedings) Joint Work

Novel processes locally to modify aluminum die cast for improving its fatigue strength

R. Izawa, O. Umezawa

5th Inter. Workshop on New Method of Damage and Failure Analysis of Structural Parts 65 - 70 2012.9 [Reviewed]

Language：English Publishing type：Research paper (international conference proceedings) Joint Work

Theoretical investigations of interstitial atoms in bcc metals: Local lattice distortion and diffusion barrier

Chun-Xia Li, Hu-Bin Luo, Qing-Miao Hu, Fu-Xing Yin, Osamu Umezawa, Rui Yang

Computational Materials Science 58 67 - 70 2012.6 [Reviewed]

DOI Web of Science

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER Joint Work

First-principles determinations of geometric structure and phase stability of α" phase in binary Ti-xM (M=V, Nb, Mo, and Ta) alloys

Chun-Xia Li, Qing-Miao Hu, Fu-Xing Yin, Osamu Umezawa, Rui Yang

Proceedings of the 12th World Conference on Titanium 3 2121 - 2125 2012.6 [Reviewed]

Language：English Publishing type：Research paper (international conference proceedings) Joint Work

Analysis of heterogeneous deformation behavior by full constraints model in alpha-titanium alloy

M. Morita, O. Umezawa

Proceedings of the 12th World Conference on Titanium 2 1100 - 1103 2012.6 [Reviewed]

Language：English Publishing type：Research paper (international conference proceedings) Joint Work

A modeling approach to evaluate grain interaction induced by {111}<1-10> planar slips in face centered cubic polycrystalline materials

M. Morita, O. Umezawa

ISIJ International 52 ( 6 ) 1163 - 1171 2012.6 [Reviewed]

DOI Web of Science CiNii Research

Language：English Publishing type：Research paper (scientific journal) Publisher：IRON STEEL INST Joint Work

Other Link： https://www.jstage.jst.go.jp/article/isijinternational/52/6/52_1153/_article

Quantitative analysis of tensile deformation behavior by In-Situ neutron diffraction for Ferrite-Martensite type dual-phase steels

Morooka, Satoshi; Umezawa, Osamu; Harjo, Stefanus; Hasegawa, Kohei; Toji, Yuki

TETSU TO HAGANE-JOURNAL OF THE IRON AND STEEL INSTITUTE OF JAPAN 98 ( 6 ) 311 - 319 2012.6 [Reviewed]

DOI Web of Science CiNii Research J-GLOBAL

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：IRON STEEL INST JAPAN KEIDANREN KAIKAN Joint Work

Other Link： https://www.jstage.jst.go.jp/article/tetsutohagane/98/6/98_311/_article/-char/ja/

Quantitative Analysis of Tensile Deformation Behavior by In-Situ Neutron Diffraction for Ferrite-Martensite Type Dual-Phase Steels

Morooka Satoshi, Umezawa Osamu, Harjo Stefanus, Hasegawa Kohei, Toji Yuki

TETSU TO HAGANE-JOURNAL OF THE IRON AND STEEL INSTITUTE OF JAPAN 98 ( 6 ) 311 - 319 2012.6 [Reviewed]

DOI Web of Science

Language：English Publishing type：Research paper (scientific journal) Publisher：THE IRON AND STEEL INSTITUTE OF JAPAN Joint Work

Other Link： https://www.jstage.jst.go.jp/article/tetsutohagane/98/6/98_311/_article/-char/ja/

Fatigue crack growth under mixed mode loading of 18CrMo4 steel

Jan Brumek, Osamu Umezawa, Vratislav Mares

21st International Conference on Metallurgy and Materials (METAL 2012) 521 - 526 2012.5 [Reviewed]

Web of Science

Language：English Publishing type：Research paper (international conference proceedings) Publisher：TANGER LTD Joint Work

Effects of alloying elements on the Snoek-type relaxation in Ti-Nb-X-O alloys (X=Al, Sn, Cr, and Mn)

H. Lu, C.X. Li, F.X. Yin, Q.F. Fang, O. Umezawa

Materials Science and Engineering A 541 28 - 32 2012.4 [Reviewed]

DOI Web of Science

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER Joint Work

Microstructural softening of eutectic and hyper-eutectic Al-Si-X continuous casts by annealing

J. Oshikiri, O. Umezawa, N. Nakamura

Transactions of the Materials Research Society of Japan 37 ( 1 ) 39 - 43 2012.3 [Reviewed]

DOI CiNii Research

Language：English Publishing type：Research paper (scientific journal) Publisher：The Materials Research Society of Japan Joint Work

Other Link： https://www.jstage.jst.go.jp/article/tmrsj/37/1/37_39/_article

Effects of alloying elements on the oxygen Snoek-type relaxation in Ti-Nb alloys

Hui Lu, Chunxia Li, Fuxing Yin, Qianfeng Fang, Osamu Umezawa

Solid State Phenomena 184 75 - 80 2012.1 [Reviewed]

DOI Web of Science

Language：English Publishing type：Research paper (scientific journal) Publisher：TRANS TECH PUBLICATIONS LTD Joint Work

Microstructural analysis of type 304 metal sleeve

S. Ohtani, S. Morooka, O. Umezawa

Materials Science Forum 702-703 959 - 962 2011.12 [Reviewed]

DOI Web of Science

Language：English Publishing type：Research paper (scientific journal) Publisher：TRANS TECH PUBLICATIONS LTD Joint Work

Slip deformation analysis based on full constraints model for α-titanium alloy at low temperature

M. Morita, O. Umezawa

Materials Transactions 52 ( 8 ) 1595 - 1602 2011.8 [Reviewed]

DOI Web of Science CiNii Research

Language：English Publishing type：Research paper (scientific journal) Publisher：Japan Institute of Metals Joint Work

Other Link： https://www.jstage.jst.go.jp/article/matertrans/52/8/52_L-M2011815/_article

Effects of Fe addition on the Snoek-type damping behavior of surface-oxidation-treated Ti-Mo alloys

Hui Lu, Chunxia Li, Fuxing Yin, Qianfeng Fang, Osamu Umezawa

Metallurgical and Materials Transactions A 42 ( 8 ) 2242 - 2249 2011.8 [Reviewed]

DOI Web of Science CiNii Research

Language：English Publishing type：Research paper (scientific journal) Publisher：ASM International Joint Work

Other Link： https://link.springer.com/article/10.1007%2Fs11661-011-0616-0

Analysis of crystal rotation by Taylor theory

M. Morita, O. Umezawa

Proceedings of the 2011 Annual Conference on Experimental and Applied Mechanics, Optical measurements, Modeling and Metrolog 5 91 - 96 2011.6

Language：English Publishing type：Research paper (international conference proceedings) Joint Work

Softening and fatigue fracture of Al-Si-X alloy casts

J. Oshikiri, O. Umezawa and N. Nakamura

JSAE Annual Congress Proceedings 19 ( 11 ) 5 - 8 2011.5

CiNii Research

Language：English Publishing type：Research paper (other science council materials etc.) Publisher：JSAE Joint Work

In-situ neutron diffraction study on work-hardening behavior in a ferrite-martensite dual phase steel

S. Morooka, N. Sato, M. Ojima, S. Harjo, Y. Adachi, Y. Tomota and O. Umezawa

JSAE Annual Congress Proceedings 19 ( 11 ) 9 - 14 2011.5

CiNii Research

Language：English Publishing type：Research paper (other science council materials etc.) Publisher：JSAE Joint Work

Snoek-type damping behavior of surface oxidation-treated Ti-Mo alloys

Hui Lu, Chunxia Li, Fuxing Yin, Qianfeng Fang, Osamu Umezawa

Materials Science and Engineering A 528 ( 9 ) 3358–3366 2011.4 [Reviewed]

DOI Web of Science

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER Joint Work

Influence of heterogeneous deformation on microstructural cracking in alpha-titanium alloys

M. Morita, S. Morooka, O. Umezawa

TMS Supplemental Proceedings: Vol. 3: General Paper Selections 427 - 431 2011.2 [Reviewed]

Web of Science

Language：English Publishing type：Research paper (international conference proceedings) Publisher：JOHN WILEY & SONS Joint Work

Subjects on fatigue crack generation in high strength alloys for long-life design

O. Umezawa,S.Morooka

ENERGY, ENVIRONMENT AND BIOLOGICAL MATERIALS 685 278 - 284 2011

DOI Web of Science

Language：English Publishing type：Research paper (international conference proceedings) Publisher：TRANS TECH PUBLICATIONS LTD Joint Work

Aluminum material flow in Japan and novel processes utilizing secondary alloys

O. Umezawa, S. Kumai

Proc. 12th International Conference of Aluminum Alloys 214 - 218 2010.9 [Reviewed]

Language：English Publishing type：Research paper (international conference proceedings) Joint Work

Softening and fatigue fracture of Al-Si-X alloys

J. Oshikiri, N. Nakamura, O. Umezawa

Proc. 12th International Conference of Aluminum Alloys 2381 - 2386 2010.9 [Reviewed]

Language：English Publishing type：Research paper (international conference proceedings) Joint Work

Evaluation of heterogeneous slip deformation by Taylor analysis

M. Morita, O. Umezawa

4th Inter. Workshop on New Method of Damage and Failure Analysis of Structural Parts 71 - 75 2010.9 [Reviewed]

CiNii Research

Language：English Publishing type：Research paper (international conference proceedings) Publisher：Vysoká škola báňská - Technická univerzita Ostrava Joint Work

Relationship between subsurface fatigue crack generation and strain incompatibility

O. Umezawa

4th Inter. Workshop on New Method of Damage and Failure Analysis of Structural Parts 65 - 70 2010.9 [Reviewed]

CiNii Research

Language：English Publishing type：Research paper (international conference proceedings) Publisher：Vysoká škola báňská - Technická univerzita Ostrava Single Work

Modeling of crack generation and growth under rolling contact fatigue in martensite steels

O.Umezawa, T. Nishikawa, T. Tsuchida, K. Hiraoka

Proc. 18th International Symposium on Processing and Fabrication of Advanced Materials (PFAM18) ( 2 ) 555 - 564 2009.12

Language：English Publishing type：Research paper (international conference proceedings) Joint Work

Subsurface fatigue crack generation and strain incompatibility near grain boundaries for a nitrogen-strengthened austenitic steel at cryogenic temperature

Osamu Umezawa

ISIJ International 49 ( 10 ) 1624 - 1629 2009.10 [Reviewed]

DOI Web of Science

Language：English Publishing type：Research paper (scientific journal) Publisher：The Iron and Steel Institute of Japan Single Work

Electron backscatter diffraction analysis on rolling contact fatigue damage around small cracks in fully tempered martensite steel

O.Umezawa, Y. Yamaji, H. Suzuki

J. Jpn. Soc. Heat Treatment 49 565 - 568 2009.9 [Reviewed]

Language：English Publishing type：Research paper (international conference proceedings) Publisher：Japan Society of Heat Treatment Joint Work

Evaluation of subsurface fatigue crack life in forged Ti-6Al-4V alloys at cryogenic temperatures

Hamada, Makiko; Umezawa, Osamu

ISIJ International 49 ( 1 ) 124 - 131 2009.1 [Reviewed]

DOI Web of Science CiNii Research

Language：English Publishing type：Research paper (scientific journal) Publisher：The Iron and Steel Institute of Japan Joint Work

Other Link： https://www.jstage.jst.go.jp/article/isijinternational/49/1/49_1_124/_article

Novel process development with continuous casting and precise forging for Al-Si alloys to produce an engine piston

O.Umezawa, H. Takagi, T. Sekiguchi, T. Yamashita, N. Miyamoto

Ceramic Transactions: Environmental Issues and Waste Management Technologies in the Materials and Nuclear Industries XII 207 189 - 200 2009 [Reviewed]

DOI Web of Science

Language：English Publishing type：Research paper (international conference proceedings) Publisher：AMER CERAMIC SOC Joint Work

Framework of material stock accounts -toward assessment of material accumulation in the economic sphere

S. Hashimoto, I. Daigo, S. Murakami, K. Matsubae-Yokoyama, M. Fuse, K. Nakajima, M. Oguchi, H. Tani … Show more authors

8th Inter. Conf. Ecobalance 2008.12

Language：English Publishing type：Research paper (international conference proceedings) Joint Work

Novel techniques characterizing subsurface fatigue crack generation and crack growth in high strength forged steels

Proc. 3rd Inter. Workshop on New Method of Damage and Failure Analysis of Structural Parts 121 - 126 2008.9 [Reviewed]

Language：English Publishing type：Research paper (international conference proceedings) Joint Work

High-cycle fatigue properties of fine particle peened Fe-3mass%Si steel sheets

O. Umezawa, T. Nozaki

Proc. 3rd Inter. Workshop on New Method of Damage and Failure Analysis of Structural Parts 105 - 110 2008.9 [Reviewed]

Language：English Publishing type：Research paper (international conference proceedings) Joint Work

Orientation relationship for fine grains formed by diffusion-induced recrystallization in the Ni(Cu) system

Y. Kawanami, M. Kajihara, O. Umezawa

Materials Transactions 49 ( 2 ) 242 - 249 2008.2 [Reviewed]

DOI Web of Science

Language：English Publishing type：Research paper (scientific journal) Publisher：JAPAN INST METALS Joint Work

Effects of thermo-mechanical treatment on the tensile and compressive properties of a glass-balloon-dispersed aluminum alloy composite

Shiga, Akira; Umezawa, Osamu

Materials Transactions 48 ( 12 ) 3088 - 3094 2007.12 [Reviewed]

DOI Web of Science

Language：English Publishing type：Research paper (scientific journal) Publisher：JAPAN INST METALS Joint Work

Proposal of index of cyclic material use in green environmental profiles

Shiga, Akira; Umezawa, Osamu

Materials Transactions 48 ( 12 ) 3050 - 3055 2007.12 [Reviewed]

DOI Web of Science

Language：English Publishing type：Research paper (scientific journal) Publisher：JAPAN INST METALS Joint Work

Al-Si系二次合金の加工熱処理におけるＬＣＡ評価

中本宗文、梅澤　修

創立20周年記念論文集「世界をリードする日本のものづくり鍛造基盤技術のトレンドを追う“アルミニウム鍛造技術”」 2006.10

Language：Japanese Publishing type：Research paper (other science council materials etc.) Joint Work

Mechanical properties of thermomechanical treated hyper-eutectic Al-Si-(Fe,Mn,Cu) materials

O.Umezawa

Materials Transactions 46 ( 12 ) 2616 - 2623 2005.12 [Reviewed]

DOI Web of Science

Language：English Publishing type：Research paper (scientific journal) Publisher：JAPAN INST METALS Single Work

Other Link： https://www.jstage.jst.go.jp/article/matertrans/46/12/46_12_2616/_article

Microstructural refinement of hyper-eutectic Al-Si-Fe-Mn cast alloys to produce a recyclable wrought material

M. Nakamoto, Y. Osawa, K. Suzuki, S. Kumai

Materials Transactions 46 ( 12 ) 2609 - 2615 2005.12 [Reviewed]

DOI Web of Science

Language：English Publishing type：Research paper (scientific journal) Publisher：JAPAN INST METALS Joint Work

Other Link： https://www.jstage.jst.go.jp/article/matertrans/46/12/46_12_2609/_article

X-ray Imaging of Cast Microstructure by Using Ultra-bright Synchrotron Radiation

UMEZAWA Osamu,HARA Toru,OHMURA Takahito

Journal of Japan Foundry Engineering Society 77 ( 11 ) 759 - 763 2005.11 [Reviewed]

DOI CiNii Research J-GLOBAL

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Japan Foundry Engineering Society Joint Work

Other Link： https://www.jstage.jst.go.jp/article/jfes/77/11/77_11_759/_article

Mechanical Properties of Thermomechanical Treated Hyper-eutectic Al-Si-X Materials

Y. Osawa, S. Takamori

Advances in Ecomaterials 2 480 - 484 2005.7

Language：English Publishing type：Research paper (international conference proceedings) Joint Work

Microstructural refinement of hyper-eutectic Al-Si-X casts to produce a heavily deformable material toward recycling-based society

O.Umezawa,S Nakamoto

6th Inter. Conf. Ecobalance 633 - 636 2004.10

Language：English Publishing type：Research paper (international conference proceedings) Joint Work

Development of civic model on materials technology for recycling-based society

Trans. Mater. Res. Soc. Jpn. 29 ( 5 ) 1829 - 1832 2004.8 [Reviewed]

Language：English Publishing type：Research paper (scientific journal) Joint Work

A state of the art and development in materials process design and technology for sustainable society

Trans. Mater. Res. Soc. Jpn. 29 ( 5 ) 1925 - 1930 2004.8 [Reviewed]

Language：English Publishing type：Research paper (scientific journal) Joint Work

Analysis on Refinement of Columnar γ Grain by Phosphorus in Continuously Cast 0.1mass% Carbon Steel

N. Yoshida, O. Umezawa and K. Nagai

ISIJ International 44 ( 3 ) 547 - 555 2004.3 [Reviewed]

DOI

Language：English Publishing type：Research paper (scientific journal) Publisher：The Iron and Steel Institute of Japan Joint Work

Other Link： https://www.jstage.jst.go.jp/article/isijinternational1989/44/3/44_3_547/_article

Effects of partial recrystallization on high-cycle fatigue deformation and crack generation of a nitrogen-strengthened 32Mn-7Cr austenitic steel at liquid nitrogen temperature

O.Umezawa

Metall. Mater. Trans. A 35A ( 2 ) 543 - 553 2004.2 [Reviewed]

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Language：English Publishing type：Research paper (scientific journal) Publisher：MINERALS METALS MATERIALS SOC Single Work

True stress-true strain relations with very low strain rates at room temperature for an austenitic 25Cr-19Ni steel

N. Tsuchida, E. Baba, O. Umezawa, K. Nagai and Y. Tomota

ISIJ International 44 ( 1 ) 209 - 213 2004.1 [Reviewed]

DOI CiNii Research

Language：English Publishing type：Research paper (scientific journal) Publisher：The Iron and Steel Institute of Japan Joint Work

Other Link： https://www.jstage.jst.go.jp/article/isijinternational1989/44/1/44_1_209/_article

Influence of phosphorus micro-segregation on ferrite structure in cast strips of 0.1 mass%C steel

O. Umezawa, K. Hirata and K. Nagai

Materials Transaction 44 ( 7 ) 1266 - 1270 2003.7 [Reviewed]

DOI CiNii Research

Language：English Publishing type：Research paper (scientific journal) Publisher：The Japan Institute of Metals and Materials Joint Work

Other Link： https://www.jstage.jst.go.jp/article/matertrans/44/7/44_7_1266/_article

Phosphorus-induced dislocation structure variation in the warm-rolled ultrafine-grained low-carbon steels

F. Yin, T. Hanamura, O. Umezawa and K. Nagai

Mater. Sci. and Eng. A 354 ( 1-2 ) 31 - 39 2003.4 [Reviewed]

DOI Web of Science

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER Joint Work

High-cycle fatigue fracture of high strength steels with modified microstructures

S. Shimakura and O. Umezawa

FATIGUE 2003: Fatigue & Durability Assessment of Materials, Components & Structures 505 - 512 2003.4 [Reviewed]

Language：English Publishing type：Research paper (international conference proceedings) Joint Work

Influence of phosphorus on solidification structure in continuously cast 0.1 mass% carbon steel

N. Yoshida, O. Umezawa and K. Nagai

ISIJ International 43 ( 3 ) 348 - 357 2003.3 [Reviewed]

DOI CiNii Research

Language：English Publishing type：Research paper (scientific journal) Publisher：The Iron and Steel Institute of Japan Joint Work

Other Link： https://www.jstage.jst.go.jp/article/isijinternational1989/43/3/43_3_348/_article

Three-dimensional distribution, morphology and nucleation site of intergranular ferrite formed in association with inclusions

T. Yokomizo, M. Enomoto, O. Umezawa, G. Spanos and R.O. Rosenberg

Mater. Sci. and Eng. A 344 261 - 267 2003.2 [Reviewed]

Language：English Publishing type：Research paper (scientific journal) Joint Work

A stae of the art and development in mini-mill process technology for sustainable steel

Osamu Umezawa

7 ( 7 ) 27 - 36 2002.7 [Reviewed]

CiNii Research J-GLOBAL

Language：Japanese Publishing type：Research paper (scientific journal) Single Work

Microstructure of cast strip in 0.1 mass%C steels containing phosphorus

HIRATA Koichi,UMEZAWA Osamu,NEGAMI Kotobu

Materials Transaction 43 ( 3 ) 305 - 310, 2002.3 [Reviewed]

CiNii Research

Language：English Publishing type：Research paper (scientific journal) Publisher：The Japan Institute of Metals and Materials Joint Work

Other Link： https://www.jstage.jst.go.jp/article/matertrans/43/3/43_3_305/_article

Continuously cast 0.1 wt% C steels with high phosphorus: microstructural design and control

O. Umezawa, N. Yoshida, K. Hirata, T. Higuchi, N. Sakuma and K. Nagai

J. Advanced Science 13 ( 3 ) 175 - 178 2002.3 [Reviewed]

DOI CiNii Research

Language：English Publishing type：Research paper (scientific journal) Publisher：Society of Advanced Science Joint Work

Other Link： https://www.jstage.jst.go.jp/article/jsas1989/13/3/13_3_175/_article

Improvement of strength-and-toughness balance of recycled steel through ultrarefinement of grain size

T. Hanamura, T. Yamashita, O. Umezawa, S. Torizuka and K. Nagai

J. Advanced Science 13 ( 3 ) 179 - 182 2002.3 [Reviewed]

DOI CiNii Research

Language：English Publishing type：Research paper (scientific journal) Publisher：Society of Advanced Science Joint Work

Other Link： https://www.jstage.jst.go.jp/article/jsas1989/13/3/13_3_175/_article

Application of the Kocks-Mecking model to tensile deformation of an austenitic 25Cr-19Ni steel

N. Tsuchida, Y. Tomota, H. Moriya, O. Umezawa and K. Nagai

Acta Materialia 49 ( 15 ) 3029 - 3038 2001.12 [Reviewed]

DOI Web of Science

Language：English Publishing type：Research paper (scientific journal) Publisher：PERGAMON-ELSEVIER SCIENCE LTD Joint Work

Cyclic damage of some high strength alloys showing subsurface crack generation in high-cycle fatigue

O.Umezawa

Proc. Second Inter. Sympo. on Environmentally Concious Design and Inverse Manufacturing 426 - 431 2001.12 [Reviewed]

Web of Science

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE COMPUTER SOC Single Work

Effects of microstructural refinement by repeated thermomechanical treatment on mechanical properties for hyper-eutectic Al-Si-(Fe, Cu) cast materials

O. Umezawa, H. Yokoyama and K. Nagai

Advances in Materials Engineering and Technology, Special Pub. of Inter. J. of Materials and Product Technology, SPM1 2 568 - 573 2001.12 [Reviewed]

Web of Science

Language：English Publishing type：Research paper (international conference proceedings) Publisher：INDERSCIENCE ENTERPRISES LTD Joint Work

現代の和釘の機械的性質とはいかなるものか

梅澤　修

ふぇらむ 6 ( 10 ) 805 - 809 2001.10 [Reviewed]

CiNii Research J-GLOBAL

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：社団法人日本鉄鋼協会 Single Work

Improvement of strength-and-toughness balance through ultrafinement of grain size

Inter. Sympo. on Ultrafine Grained Steels (ISUGS 2001) 228 - 231 2001.9 [Reviewed]

Language：English Publishing type：Research paper (international conference proceedings) Joint Work

Time dependent flow behavior of pure aluminium and aluminium-magnesium alloy under a constant stress condition

K. Ishikawa, F. Ishikawa, M. Maehara, Y. Kobayashi and O. Umezawa

CREEP 7 407 - 409 2001.6 [Reviewed]

Language：English Publishing type：Research paper (other science council materials etc.) Joint Work

Fabrication of Ni3Al thin foil by cold rolling

M. Demura, Y. Suga, O. Umezawa, K. Kishida, E.P. George and T. Hirano

Intermetallics 9 ( 2 ) 157 - 167 2001.2 [Reviewed]

DOI Web of Science

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER Joint Work

Ductile thin foil of Ni3Al

M. Demura, K. Kishida, O. Umezawa, E.P. George and T. Hirano

Mechanical properties of structural films 1413 248 - 261 2001.2 [Reviewed]

Web of Science

Language：English Publishing type：Research paper (international conference proceedings) Publisher：AMERICAN SOCIETY TESTING AND MATERIALS Joint Work

Shape, size and crystallographic orientation of the ferrite grains formed at grain boundaries of deformed austenite in a low carbon steel

TORIZUKA Shiro,UMEZAWA Osamu,TSUZAKI Kaneyoshi,NAGAI Kotobu

Tetsu to Hagane 86 ( 12 ) 807 - 814 2000.12

DOI CiNii Research

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：THE IRON AND STEEL INSTITUTE OF JAPAN Joint Work

Internal crack initiation in high-cycle fatigue of Ti-Fe-O alloy at liquid nitrogen temperature

H. Yokoyama, O. Umezawa, K. Nagai, T. Suzuki and K. Kokubo

Titanium'99 Sci. and Tech. 622 - 629 2000.12

Language：English Publishing type：Research paper (international conference proceedings) Joint Work

Cyclic deformation, dislocation structure and internal fatigue crack generation in Ti-Fe-O alloy at liquid nitrogen temperature

H. Yokoyama, O. Umezawa, K. Nagai, T. Suzuki and K. Kokubo

Metall. Mater. Trans. A 31 ( 11 ) 2793 - 2805 2000.11 [Reviewed]

CiNii Research

Language：English Publishing type：Research paper (scientific journal) Publisher：ASM International Joint Work

Relationship between size, shape and crystallographic orientation of ferrite grains formed at grain boundaries of deformed austenite in a low carbon steel

S. Torizuka, O. Umezawa, K. Tsuzaki and K. Nagai

HSLA Steel `2000 255 - 259 2000.6 [Reviewed]

Language：English Publishing type：Research paper (international conference proceedings) Joint Work

Changes in Primary Crystal Morphology of Al-Si Alloys at Solid-Liquid Coexisting Temperatures by Ultrasonic Vibration

OSAWA Yoshiaki,TAKAMORI Susumu,ARAKANE Goro,UMEZAWA Osamu,Sato Akira,OHASHI Osamu

Journal of Japan Foundry Engineering Society 72 ( 3 ) 187 - 192 2000.3 [Reviewed]

DOI CiNii Research

Language：English Publishing type：Research paper (scientific journal) Publisher：Japan Foundry Engineering Society Joint Work

Other Link： https://www.jstage.jst.go.jp/article/jfes/72/3/72_3_187/_article

Description of stress-strain curves based on thermal activation models for a Ti-Fe-O alloy at 77 to 296 K with strain rates from 10-9 to 10-2 sec-1

N. Tsuchida, H. Moriya, Y. Tomota, O. Umezawa and K. Nagai

ISIJ International 40 ( 1 ) 84 - 90 2000.1

DOI Web of Science

Language：English Publishing type：Research paper (scientific journal) Publisher：IRON STEEL INST JAPAN Joint Work

Hot extrusion for Al-Si-(Fe, Cu) hyper-eutectic cast alloys

H. Yokoyama, O. Umezawa, K. Nagai and K. Kokubo

4th Inter. Conf. ECOMATERIALS 491 - 494 1999.11 [Reviewed]

Language：English Publishing type：Research paper (international conference proceedings) Joint Work

Influence of silicon crystal size on fatigue property in hyper-eutectic Al-Si alloy

H. Yokoyama, O. Umezawa, K. Nagai and K. Kokubo

6th Jpn. Inter. SAMPE Sympo. 357 - 360 1999.10 [Reviewed]

Language：English Publishing type：Research paper (international conference proceedings) Joint Work

Microstructural refinement of an As-Cast Al-12.6 Wt Pct Si alloy by repeated thermomechanical treatment to produce a heavily deformable material

O. Umezawa and K. Nagai

Metall. Mater. Trans. A 30A ( Aug ) 2221 - 2228 1999.8 [Reviewed]

DOI CiNii Research

Language：English Publishing type：Research paper (scientific journal) Publisher：ASM International Joint Work

Other Link： https://link.springer.com/article/10.1007%2Fs11661-999-0034-8

Effects of high magnetic field on recrystallization and coarsening behavior in Fe-Si steels

Y. Xu, H. Ohtsuka, O. Umezawa, K. Anak, S. Miyazaki and H. Wada

4th Inter. Conf. on Recrystallization and Related Phenomena 571 - 576 1999.7 [Reviewed]

Language：English Publishing type：Research paper (international conference proceedings) Joint Work

Electron microscopy study of cyclic deformation in Ti-Fe-O alloy at low temperature

O. Umezawa, H. Yokoyama, K. Nagai, T. Suzuki and K. Kokubo

FATIGUE '99 211 - 216 1999.6 [Reviewed]

Web of Science

Language：English Publishing type：Research paper (international conference proceedings) Publisher：CHINA HIGHER EDUCATION PRESS BEIJING Joint Work

Effect of strain rate and deformation temperature on fine ferrite grain structure formed from heavily deformed austenite

S. Torizuka, O. Umezawa, K. Tsuzaki, K. Nagai, S. Genda and Y. Kogo

Proc. Inter. Conf. on Solid-Solid Trans. `99 (JIMIC-3) 1533 - 1536 1999.5 [Reviewed]

Language：English Publishing type：Research paper (international conference proceedings) Publisher：JAPAN INST METALS Joint Work

Fracture characteristics and deformation behavior of solution-treated Ti-15V-3Cr-3Sn-3Al alloy

H. Moriya, K. Nagai and O. Umezawa

Int. J. of Materials and Product Technology 14 ( 2-4 ) 229 - 243 1999.4 [Reviewed]

DOI Web of Science

Language：English Publishing type：Research paper (other science council materials etc.) Publisher：INDERSCIENCE ENTERPRISES LTD Joint Work

Fabrication of large-grained binary stoichiometric Ni3Al

T. Hirano, M. Demura, E.P. George and O. Umezawa

Scripta Materialia 40 ( 1 ) 63 - 69 1999.1 [Reviewed]

DOI Web of Science

Language：English Publishing type：Research paper (scientific journal) Publisher：PERGAMON-ELSEVIER SCIENCE LTD Joint Work

Effects of test temperature on internal fatigue crack generation associated with nonmetallic particles in austenitic steels

O. Umezawa and K. Nagai

Metall. Mater. Trans. A 29 ( 12 ) 3017 - 3028 1998.12 [Reviewed]

DOI CiNii Research

Language：English Publishing type：Research paper (scientific journal) Publisher：ASM International Joint Work

Other Link： https://link.springer.com/article/10.1007%2Fs11661-998-0209-8

Recrystallization in binary stoichiometric Ni3Al

T. Hirano, M. Demura, E.P. George and O. Umezawa

Grain Growth in Polycrystalline Materials Ⅲ 683 - 688 1998.12 [Reviewed]

Web of Science

Language：English Publishing type：Research paper (international conference proceedings) Publisher：METALS & MATERIALS SOC Joint Work

Influence of low temperature working on microstructure and mechanical properties of Al-7Si-(Fe) alloys

C.-Y. Lim, O. Umezawa and K. Nagai

Metals and Materials 4 ( 5 ) 1027 - 1031 1998.10 [Reviewed]

DOI Web of Science

Language：English Publishing type：Research paper (scientific journal) Publisher：KOREAN INST METALS MATERIALS Joint Work

Refinement of ferrite-pearlite structures through transformation from heavily deformed austenite in a low carbon Si-Mn steel

S. Torizuka, O. Umezawa, K. Tsuzaki and K. Nagai

Materials Science Forum 284-2 225 - 230 1998.8 [Reviewed]

DOI Web of Science

Language：English Publishing type：Research paper (scientific journal) Publisher：TRANSTEC PUBLICATIONS LTD Joint Work

Deformation structure and subsurface fatigue crack generation in austenitic steels at low temperature

O. Umezawa and K. Nagai

Metall. Mater. Trans. A 29A ( 3 ) 809 - 822 1998.3 [Reviewed]

DOI CiNii Research

Language：English Publishing type：Research paper (scientific journal) Publisher：ASM International Joint Work

Other Link： https://link.springer.com/article/10.1007%2Fs11661-998-0272-1

Distribution of internal crack initiation sites in high-cycle fatigue for titanium alloys

H. Yokoyama, O. Umezawa, K. Nagai and T. Suzuki

ISIJ International 37 ( 12 ) 1237 - 1244 1997.12 [Reviewed]

DOI CiNii Research

Language：English Publishing type：Research paper (scientific journal) Publisher：The Iron and Steel Institute of Japan Joint Work

Other Link： https://www.jstage.jst.go.jp/article/isijinternational1989/37/12/37_12_1237/_article

Effects of microstructure on the subsurface crack initiation of Ti-6Al-4V alloys

O. Umezawa, K. Nagai, H. Yokoyama and T. Suzuki

High Cycle Fatigue of Structural Materials 287 - 298 1997.12 [Reviewed]

Web of Science

Language：English Publishing type：Research paper (international conference proceedings) Publisher：METALS & MATERIALS SOC Joint Work

Metastable alloy phase formation from undercooled steel and Ti-Al melts

S. Tsukamoto and O. Umezawa

Materials Science and Engineering A 223 99 - 113 1997.10 [Reviewed]

DOI Web of Science

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER Joint Work

Microstructural design and processing of plasticized hyper-eutectic Al-Si-Fe alloys

O. Umezawa and K. Nagai

Proc. 3rd Inter. Conf. ECOMATERIALS 59 - 62 1997.10 [Reviewed]

Language：English Publishing type：Research paper (international conference proceedings) Joint Work

Microstructural design and processing of hyper-eutectic Al-Si alloy and its deformation behavior

O. Umezawa and K. Nagai

Proc. 3rd Inter. Conf. ECOMATERIALS 91 - 94 1997.10 [Reviewed]

Language：English Publishing type：Research paper (international conference proceedings) Joint Work

Microstructural control of recyclable Al-Si-Fe alloys by low temperature working process

C.-Y. Lim, O. Umezawa and K. Nagai

Proc. 3rd Inter. Conf. ECOMATERIALS 99 - 102 1997.10 [Reviewed]

Language：English Publishing type：Research paper (international conference proceedings) Joint Work

Fatigue crack initiation site in titanium alloys at cryogenic temperatures

K. Nagai, T. Yuri and O. Umezawa

Titanium'95 Sci. and Tech. Ⅱ 1139 - 1146 1996.12 [Reviewed]

Language：English Publishing type：Research paper (international conference proceedings) Joint Work

Recyclable design and heavily plasticization for an eutectic Al-Si cast alloy

O. Umezawa and K. Nagai

Trans. of the Mater. Res. Soc. of Jpn 20 190 - 193 1996.10 [Reviewed]

Language：English Publishing type：Research paper (scientific journal) Joint Work

材料組織観察における不均一性の抽出と把握の重要性

日本金属学会金属組織観察の基礎と最近の進歩（金属学会セミナー） 35 - 42 1996.7

Language：Japanese Publishing type：Research paper (other science council materials etc.) Single Work

Phenomenological aspects of fatigue life and fatigue crack initiation in high strength alloys at cryogenic temperature

O. Umezawa and K. Ishikawa

Materials Science and Engineering A 176 ( 1-2 ) 397 - 403 1994 [Reviewed]

DOI Web of Science

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER Joint Work

Review of high cycle fatigue properties of structural materials at cryogenic temperatures

O. Umezawa, T. Ogata, T. Yuri, K. Nagai and K. Ishikawa

Advances in Cryogenic Engineering Materials 40 1231 - 1238 1994 [Reviewed]

Web of Science

Language：English Publishing type：Research paper (international conference proceedings) Publisher：PLENUM PRESS DIV PLENUM PUBLISHING CORP Joint Work

High cycle fatigue properties of Ti-6Al-4V alloys at cryogenic temperatures

K. Nagai, T. Yuri, O. Umezawa, T. Ogata, K. Ishikawa, Y. Ito and T. Nishimura

Titanium `92 Sci. and Tech. Ⅱ 1827 - 1834 1993.12

Language：English Publishing type：Research paper (international conference proceedings) Joint Work

Fatigue testing and properties of structural materials at cryogenic temperatures

K. Ishikawa, T. Yuri, O. Umezawa, K. Nagai and T. Ogata

Fusion Engineering and Design 20 429 - 435 1993 [Reviewed]

DOI Web of Science

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER Joint Work

High-cycle fatigue properties of titanium alloys at cryogenic temperatures

O. Umezawa, K. Nagai, T. Yuri, T. Ogata and K. Ishikawa

Advances in Cryogenic Engineering Materials 38 175 - 182 1992.12 [Reviewed]

Language：English Publishing type：Research paper (international conference proceedings) Joint Work

Deformation structures in high-cycle fatigue of 0.1N-32Mn-7Cr steel at cryogenic temperatures

O. Umezawa and K. Ishikawa

Advances in Cryogenic Engineering Materials 38 141 - 148 1992.12 [Reviewed]

Web of Science

Language：English Publishing type：Research paper (international conference proceedings) Publisher：PLENUM PRESS DIV PLENUM PUBLISHING CORP Joint Work

Electrical and thermal conductivities and magnetization of some austenitic steels, titanium and titanium alloys at cryogenic temperatures

O. Umezawa and K. Ishikawa

Cryogenics 32 ( 10 ) 873 - 880 1992.10 [Reviewed]

DOI Web of Science

Language：English Publishing type：Research paper (scientific journal) Publisher：BUTTERWORTH-HEINEMANN LTD Joint Work

Fatigue properties of cold-rolled and sensitized SUS347 austenitic stainless steels at cryogenic temperatures

T. Yuri, K. Ishikawa, K. Nagai, T. Ogata and O. Umezawa

Cryogenics 32 ( ICMC Supplement ) 89 - 92 1992 [Reviewed]

Language：English Publishing type：Research paper (international conference proceedings) Joint Work

Effect of strain rate on tensile behavior of some alloys at liquid helium temperature

K. Ishikawa, T. Ogata, T. Yuri, K. Nagai and O. Umezawa

Cryogenics 32 ( ICMC Supplement ) 67 - 70 1992 [Reviewed]

Language：English Publishing type：Research paper (international conference proceedings) Joint Work

High cycle fatigue of some austenitic steels at cryogenic temperatures"

K. Nagai, T. Yuri, O. Umezawa, T. Ogata and K. Ishikawa

Proc. Inter. Conf. on Stainless Steels 465 - 472 1991.10 [Reviewed]

Language：English Publishing type：Research paper (international conference proceedings) Joint Work

Discontinuous deformation of austenitic stainless steels in liquid helium

K. Ishikawa, T. Ogata, K. Nagai, T. Yuri and O. Umezawa

Proc. Inter. Conf. on Stainless Steels 449 - 456 1991.10

Language：English Publishing type：Research paper (international conference proceedings) Joint Work

Strength and toughness of austenitic stainless steels at cryogenic temperatures"

T. Ogata, K. Ishikawa, K. Nagai, T. Yuri and O. Umezawa

Proc. Inter. Conf. on Stainless Steels 457 - 464 1991.10 [Reviewed]

Language：English Publishing type：Research paper (international conference proceedings) Joint Work

Effect of heat-treatment on physical properties of Ti-6Al-4V alloys at cryogenic temperatures

O. Umezawa, K. Nagai and K. Ishikawa

Sci. and Eng. of Light Metals 91 - 96 1991.9 [Reviewed]

Language：English Publishing type：Research paper (international conference proceedings) Joint Work

Cryogenic mechanical properties of Ti-6Al-4V alloys with three levels of oxygen content

K. Nagai, T. Yuri, T. Ogata, O. Umezawa, K. Ishikawa, T. Nishimura, T. Mizoguchi and Y. Ito

ISIJ International 31 ( 8 ) 882 - 889 1991.8 [Reviewed]

DOI CiNii Research

Language：English Publishing type：Research paper (scientific journal) Publisher：The Iron and Steel Institute of Japan Joint Work

Other Link： https://www.jstage.jst.go.jp/article/isijinternational1989/31/8/31_8_882/_article

High Cycle Fatigue Properties of Cryogenic Structural Alloys.

NAGAI Kotobu,YURI Tetsumi,UMEZAWA Osamu,OGATA Toshio,ISHIKAWA Keisuke

Journal of Cryogenics 26 ( 4 ) 255 - 262 1991.8 [Reviewed]

DOI CiNii Research

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：CRYOGENICS AND SUPERCONDUCTIVITY SOCIETY OF JAPAN Joint Work

Other Link： https://www.jstage.jst.go.jp/article/jcsj1966/26/4/26_4_255/_article/-char/ja/

Subsurface Crack Initiation in High Cycle Fatigue at Cryogenic Temperatures.

UMEZAWA Osamu,NAGAI Kotobu,YURI Tetsumi,OGATA Toshio,ISHIKAWA Keisuke

Journal of Cryogenics 26 ( 4 ) 263 - 271 1991.8 [Reviewed]

DOI CiNii Research

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：CRYOGENICS AND SUPERCONDUCTIVITY SOCIETY OF JAPAN Joint Work

Other Link： https://www.jstage.jst.go.jp/article/jcsj1966/26/4/26_4_263/_article/-char/ja/

Subsurface crack initiation in high cycle fatigue of 0.1N-32Mn-7cr steel at cryogenic temperatures

O. Umezawa, K. Nagai, T. Yuri and K. Ishikawa

Mechanical Behaviour of Materials VI 4 301 - 306 1991.7 [Reviewed]

Language：English Publishing type：Research paper (international conference proceedings) Joint Work

Specimen Temperature Rise and Testing Conditions during Fatigue Tests at Cryogenic Temperatures.

OGATA Toshio,ISHIKAWA Keisuke,NAGAI Kotobu,UMEZAWA Osamu,YURI Tetsumi

Journal of Cryogenics 26 ( 3 ) 190 - 196 1991.6 [Reviewed]

DOI CiNii Research

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：CRYOGENICS AND SUPERCONDUCTIVITY SOCIETY OF JAPAN Joint Work

Other Link： https://www.jstage.jst.go.jp/article/jcsj1966/26/3/26_3_190/_article/-char/ja/

Fatigue Testing System and Result of Long-term Operation.

YURI Tetsumi,NAGAI Kotobu,OGATA Toshio,UMEZAWA Osamu,ISHIKAWA Keisuke

Journal of Cryogenics 26 ( 3 ) 184 - 189 1991.6

DOI CiNii Research

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：CRYOGENICS AND SUPERCONDUCTIVITY SOCIETY OF JAPAN Joint Work

Other Link： https://www.jstage.jst.go.jp/article/jcsj1966/26/3/26_3_184/_article/-char/ja/

Internal crack initiation in high cycle fatigue at cryogenic temperatures

K. Nagai, O. Umezawa, T. Yuri and K. Ishikawa

Engineering Fracture Mechanics 40 ( 4-5 ) 957 - 965 1991.5 [Reviewed]

DOI Web of Science

Language：English Publishing type：Research paper (scientific journal) Publisher：PERGAMON-ELSEVIER SCIENCE LTD Joint Work

Fatigue properties of titanium alloys in liquid helium

K. Ishikawa, K. Nagai, O. Umezawa, T. Yuri and T. Ogata

JSME International J., Series I 34 ( 3 ) 347 - 350 1991.3 [Reviewed]

DOI Web of Science

Language：English Publishing type：Research paper (scientific journal) Publisher：JAPAN SOC MECHANICAL ENGINEERS Joint Work

Low cycle fatigue and other mechanical properties of aged 316LN stainless steel at liquid helium temperature

T. Ogata, K. Ishikawa, K. Nagai, O. Umezawa and T. Yuri

Advances in Cryogenic Engineering Materials, eds. R.P. Reed and F.R. Ficket, Plenum Press, New York 36 1249 - 1255 1990.12 [Reviewed]

Language：English Publishing type：Research paper (international conference proceedings) Joint Work

Low temperature creep behavior of stainless steel

T. Ogata, O. Umezawa and K. Ishikawa

Advances in Cryogenic Engineering Materials, eds. R.P. Reed and F.R. Ficket, Plenum Press,New York 36 1233 - 1239 1990.12 [Reviewed]

Language：English Publishing type：Research paper (international conference proceedings) Joint Work

Fatigue 90, eds. H. Kitagawa and T. Tanaka Internal crack initiation in high cycle fatigue of Ti-6Al-4V alloys at cryogenic temperatures

O. Umezawa, K. Nagai and K. Ishikawa

Mater. and Component Eng. Pub., Birmingham 1 267 - 272 1990.7 [Reviewed]

Language：English Publishing type：Research paper (international conference proceedings) Joint Work

Subsurface crack initiation in high cycle fatigue of Ti-6Al-4V alloys at cryogenic temperatures

UMEZAWA Osamu,NAGAI Kotobu,ISHIKAWA Keisuke

Tetsu to Hagane 76 ( 6 ) 924 - 931 1990.6 [Reviewed]

DOI CiNii Research

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：THE IRON AND STEEL INSTITUTE OF JAPAN Joint Work

Other Link： https://www.jstage.jst.go.jp/article/tetsutohagane1955/76/6/76_6_924/_article/-char/ja/

Transmission electron microscopy study of high cycle fatigue deformation in Ti-5Al-2.5Sn extra low interstitial alloy at cryogenic temperatures

O. Umezawa, K. Nagai and K. Ishikawa

Materials Science and Engineering A 129 ( 2 ) 223 - 227 1990 [Reviewed]

DOI Web of Science

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER Joint Work

Subsurface crack initiation in high cycle fatigue of Ti-5Al-2.5Sn extra-low interstitial alloy at liquid helium temperature

O. Umezawa, K. Nagai and K. Ishikawa

Materials Science and Engineering A 129 ( 2 ) 217 - 221 1990 [Reviewed]

DOI Web of Science

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER Joint Work

Internal Crack Initiation in High Cycle Fatigue for Ti-5Al-2.5Sn ELI Alloy at Cryogenic Temperatures

UMEZAWA Osamu,NAGAI Kotobu,ISHIKAWA Keisuke

Tetsu to Hagane 75 ( 1 ) 159 - 166 1989.1 [Reviewed]

DOI CiNii Research

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：THE IRON AND STEEL INSTITUTE OF JAPAN Joint Work

Other Link： https://www.jstage.jst.go.jp/article/tetsutohagane1955/75/1/75_1_159/_article/-char/ja/

Fatigue and fracture of Ti alloys at cryogenic temperatures

K. Nagai, T. Yuri, O. Umezawa and K. Ishikawa

Proc. Magnet Technology (MT-11), eds. T. Sekiguchi and S. Shimamoto, Elsevier Applied Sci., London 1 754 - 759 1989 [Reviewed]

Language：English Publishing type：Research paper (international conference proceedings) Joint Work

Creep and discontinuous deformation behavior of austenitic stainless steels at cryogenic temperatures

T. Ogata, K. Ishikawa, T. Yuri and O. Umezawa

Proc. Magnet Technology (MT-11), eds. T. Sekiguchi and S. Shimamoto, Elsevier Applied Sci., London 1 749 - 753 1989 [Reviewed]

Language：English Publishing type：Research paper (international conference proceedings) Joint Work

Effects of specimen geometry on temperature and discontinuous deformation during tensile tests at liquid helium temperature

T. Ogata, K. Ishikawa, O. Umezawa and T. Yuri

Advances in Cryogenic Engineering Materials, eds. A.F. Clark and R.P. Reed, Plenum Press,New York 34 209 - 215 1988.12 [Reviewed]

Language：English Publishing type：Research paper (international conference proceedings) Joint Work

Discontinuous deformation during load- and displacement- controlled tensile tests and optical observation in liquid helium

T. Ogata, K. Ishikawa, O. Umezawa and T. Yuri

Cryogenics 28 ( 8 ) 511 - 515 1988.8 [Reviewed]

DOI Web of Science

Language：English Publishing type：Research paper (scientific journal) Publisher：BUTTERWORTH-HEINEMANN LTD Joint Work

極低温におけるオーステナイト系ステンレス鋼の引張変形挙動と温度上昇に及ぼす試験片形状の影響

緒形俊夫，石川圭介，梅澤　修，由利哲美

低温工学 23 ( 4 ) 211 - 216 1988.4 [Reviewed]

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：公益社団法人低温工学・超電導学会 Joint Work

複合荷重下の2 1/4Cr-1Mo鋼のクリープ疲労相互作用

久保　清，八木晃一，金子隆一，梅澤　修

材料 37 ( 423 ) 67 - 73 1988 [Reviewed]

DOI CiNii Research

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：日本材料学会 Joint Work

A review on cryogenic temperature mechanical properties of Ti and its alloys

K. Nagai, T. Yuri, O. Umezawa and K. Ishikawa

Proc. Cryogenic Materials '88, eds. R.P. Reed, Z.S. Xing and E.W. Collings 2 727 - 736 1988

Language：English Publishing type：Research paper (international conference proceedings) Joint Work

Temperature measurements and direct observation in load-controlled tensile test at cryogenic temperature.

OGATA Toshio,UMEZAWA Osamu,YURI Tetsumi,ISHIKAWA Keisuke

Journal of Cryogenics 22 ( 2 ) 128 - 132 1987.4 [Reviewed]

DOI CiNii Research

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：CRYOGENICS AND SUPERCONDUCTIVITY SOCIETY OF JAPAN Joint Work

Other Link： https://www.jstage.jst.go.jp/article/jcsj1966/22/2/22_2_128/_article/-char/ja/

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