Article
Nanoscience & Nanotechnology
Nirosha D. Adasooriya, Wakshum Mekonnen Tucho, Erlend Holm, Terje Arthun, Vidar Hansen, Karl Gunnar Solheim, Tor Hemmingsen
Summary: The mechanical properties of tempered high strength carbon steel (AISI 4130) affected by hydrogen embrittlement were investigated using slow strain rate tensile tests. Results showed significant influences of hydrogen charging and tempering temperatures on the hardness and fracture characteristics of the steel.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2021)
Article
Nanoscience & Nanotechnology
Akinobu Shibata, Ivan Gutierrez-Urrutia, Kazuho Okada, Goro Miyamoto, Yazid Madi, Jacques Besson, Kaneaki Tsuzaki
Summary: The study investigated the relationship between the mechanical response and microscopic crack propagation behavior of hydrogen-related intergranular fractures in high-strength martensitic steel. The results showed that hydrogen can affect crack tip morphology and induce strain localization in the vicinity of intergranular cracks.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2022)
Article
Chemistry, Physical
Rongjian Shi, Lin Chen, Zidong Wang, Xu-Sheng Yang, Lijie Qiao, Xiaolu Pang
Summary: This study quantitatively investigated the correlation between different microstructural components and high-density hydrogen trapping in tempered niobium carbide (NbC)-precipitated martensitic steel. It was found that martensite lath and a high density of dislocations served as reversible hydrogen trapping sites, while NbC nanoprecipitates, high-angle grain boundaries, and grain-boundary precipitates acted as irreversible hydrogen traps. These findings are significant for enhancing the hydrogen embrittlement resistance of high-strength martensitic steels.
JOURNAL OF ALLOYS AND COMPOUNDS
(2021)
Article
Materials Science, Multidisciplinary
Akinobu Shibata, Yasunari Takeda, Yuuji Kimura, Nobuhiro Tsuji
Summary: This study investigates the hydrogen-related fracture behavior of as-quenched low-carbon martensitic steel under constant loading tensile tests. The findings suggest that the fracture time decreases with increasing applied stress and hydrogen content. The analysis of fracture surface topography reveals that intergranular fractures initiate from the side surface and propagate into the inner part of the specimen at low stress, while several intergranular fractures are separately initiated inside the specimen at high stress levels. The mode of hydrogen-related fracture is influenced by fracture stress rather than the global hydrogen content.
Article
Nanoscience & Nanotechnology
L. Cupertino Malheiros, A. Oudriss, S. Cohendoz, J. Bouhattate, F. Th, M. Piette, X. Feaugas
Summary: Electrochemical permeation cell built on a Instron tensile testing machine allows fracturing notched specimens under hydrogen flux while monitoring simultaneously the flow stress and the permeation anodic current. The analysis of fracture surfaces reveals that cracking initiates at the hydrogen-entry surfaces as quasi-cleavage regions followed by ductile propagation. The finite element method (FEM) calculates local failure criteria, revealing the importance of hydrogen-mechanical-structural interactions in fracture analysis.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2022)
Article
Chemistry, Physical
V. Arniella, A. Zafra, J. Belzunce, C. Rodriguez
Summary: This study focuses on the mechanical behavior of steels in hydrogen-rich environments. Tensile tests were conducted to compare the performance of 42CrMo4 steels under different hydrogen charging conditions, revealing a significant impact on strength and deformation behavior, mainly transitioning from ductile to brittle behavior.
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
(2022)
Article
Nanoscience & Nanotechnology
Takahiro Chiba, Tetsushi Chida, Tomohiko Omura, Daisuke Hirakami, Kenichi Takai
Summary: In this study, the lattice defects and plastic deformation in the local area of intergranular fracture in hydrogen-induced tempered martensitic steel were investigated using low-temperature thermal desorption spectroscopy, electron backscatter diffraction, and electron channeling contrast imaging. The results clearly indicate the essential role of local plastic deformation and associated vacancy formation in the process of hydrogen-induced intergranular fracture.
SCRIPTA MATERIALIA
(2023)
Article
Nanoscience & Nanotechnology
Tingshu Chen, Motomichi Koyama, Takahiro Chiba, Eiji Akiyama, Kenichi Takai
Summary: The effects of the misorientation of prior austenite grain boundary (PAGB) segments on the local plasticity evolution in intergranular (IG) and IG-like fractures were investigated. The study found that low-angle and sigma 3 PAGB segments allow crack-tip blunting before crack growth.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2023)
Article
Materials Science, Multidisciplinary
Aliasghar Mosayebi, Maryam Soleimani, Hamed Mirzadeh, Changiz Dehghanian
Summary: The study revealed that increasing the tempering time and temperature improved the corrosion resistance of AISI 4130 steel, while the correlation between hardness and corrosion current density (i(corr)) suggests the influence of microstructure on steel performance.
MATERIALS AND CORROSION-WERKSTOFFE UND KORROSION
(2021)
Article
Chemistry, Physical
Sang-Gyu Kim, Jae-Yun Kim, Byoungchul Hwang
Summary: The effect of tempering temperature on the hydrogen embrittlement characteristics of SCM440 tempered martensitic steels was investigated. Microstructure, hydrogen desorption behavior, and hydrogen embrittlement resistance were analyzed. It was found that an increasing tempering temperature led to improved hydrogen embrittlement resistance due to changes in microstructure and trap sites for hydrogen.
Article
Chemistry, Physical
L. B. Peral, A. Diaz, J. M. Alegre, I. I. Cuesta
Summary: This article presents a study on hydrogen uptake and transport in quenched and tempered low-alloy steel through electrochemical permeation tests. Various factors such as charging solution, current density, and surface roughness were found to have a significant effect on the behavior of hydrogen uptake and transport.
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
(2023)
Article
Nanoscience & Nanotechnology
Yota Masuda, Motomichi Koyama, Hiroshi Kakinuma, Eiji Akiyama
Summary: The effects of mechanical loading on hydrogen uptake were studied using thermal desorption experiments. The diffusible hydrogen content increased with increasing elastic and plastic strains, with a larger increase per elastic strain than per plastic strain.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2023)
Article
Mechanics
A. Zafra, G. Alvarez, J. Belzunce, J. M. Alegre, C. Rodriguez
Summary: The study used laboratory heat treatments to obtain homogeneous coarse-grain tempered bainitic/martensitic microstructures for assessing the fracture behaviour in the presence of internal hydrogen in welds. The results showed that the hydrogen embrittlement experienced by the CGHAZs of both steels was considerably greater than in the base steels.
ENGINEERING FRACTURE MECHANICS
(2021)
Article
Chemistry, Physical
Yuji Momotani, Akinobu Shibata, Nobuhiro Tsuji
Summary: The present study investigated hydrogen-related fractures in low-carbon martensitic steel at different deformation temperatures. The sensitivity to hydrogen embrittlement increased with decreasing temperature from 100 degrees C to 0 degrees C, but decreased further below 0 degrees C. The characterization of fracture surface types revealed a similar temperature dependence of hydrogen-embrittled surfaces to the sensitivity to hydrogen embrittlement. Qualitative discussion indicated that the degree of hydrogen accumulation peaked in the medium temperature range, consistent with the experimentally confirmed sensitivity to hydrogen embrittlement.
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
(2022)
Article
Chemistry, Physical
Hai Qiu, Rintaro Ueji, Tadanobu Inoue, Yuuji Kimura
Summary: The study shows that in the microstructure of tempered martensite in medium-carbon steel, Luders phenomenon is present but Portevin-Le Chatelier phenomenon is not found. The local strain distribution in tempered martensite is more complicated than that in ferrite.
Article
Materials Science, Multidisciplinary
Reza Gholizadeh, Shuhei Yoshida, Yu Bai, Shu Kurokawa, Akinobu Shibata, Nobuhiro Tsuji
Summary: In this study, the deformation behavior of the CoCrFeMnNi alloy under ultra-high strains at various temperatures was investigated. It was found that deformation twinning was extensively activated at moderate to high strains and at elevated temperatures above 600 degrees C. The alloy showed excellent deformability at low temperatures, but embrittlement occurred at intermediate temperatures. This research provides insights into the microstructure evolution and mechanical response of the Cantor alloy under shear deformation at a wide range of strains and temperatures.
Article
Nanoscience & Nanotechnology
Jesada Punyafu, Sukyoung Hwang, Shiro Ihara, Hikaru Saito, Nobuhiro Tsuji, Mitsuhiro Murayama
Summary: Carbon-containing TWIP steels, which have a great strain hardening capability, suffer from serrations on the stress-strain curves, hindering their commercial development. The impact of grain size, especially in the ultrafine-grained range, and its orientation on the serrations and plastic deformation mechanism has been overlooked. This study compared the plastic deformation behavior in fine-grained and ultrafine-grained specimens and found a change in the dominant deformation mode when the grain size was equal to or smaller than 1 μm. The alteration was strongly influenced by the grain orientation and resulted in the enhancement of strain localization and the inhibition of serrations in the ultrafine-grained specimens.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2023)
Article
Multidisciplinary Sciences
Yan Chong, Reza Gholizadeh, Tomohito Tsuru, Ruopeng Zhang, Koji Inoue, Wenqiang Gao, Andy Godfrey, Masatoshi Mitsuhara, J. W. Morris, Andrew M. Minor, Nobuhiro Tsuji
Summary: Interstitial oxygen embrittles titanium, particularly at cryogenic temperatures, which necessitates a stringent control of oxygen content in fabricating titanium and its alloys. A structural strategy, via grain refinement, has been proposed to alleviate this problem. The unique synergy of strength and ductility in the ultrafine-grained (UFG) Ti-0.3wt.%O is achieved through diluted grain boundary segregation of oxygen and enhanced dislocation activities, resulting in improved grain boundary cohesive energy and excellent strain hardening ability. This strategy not only promotes the potential applications of high strength Ti-O alloys at low temperatures but can also be applied to other alloy systems.
NATURE COMMUNICATIONS
(2023)
Article
Materials Science, Multidisciplinary
Wu Gong, Stefanus Harjo, Yo Tomota, Satoshi Morooka, Takuro Kawasaki, Akinobu Shibata, Nobuhiro Tsuji
Summary: The martensitic transformation is accompanied by the generation of internal stresses at both microscale and macroscale during cooling. Previous studies using X-ray or neutron diffraction have reported inconsistent results due to the influence of factors such as solute elements and crystal defects on the measured lattice parameter.
Article
Nanoscience & Nanotechnology
Avala Lavakumar, Myeong-heom Park, Reza Gholizadeh, Ranjit Kumar Ray, Mitsuhiro Murayama, Nobuhiro Tsuji
Summary: Low-carbon multi-phased steels with transformation induced plasticity (TRIP) effect have attracted significant attention for automotive applications due to their superior mechanical balance between strength and ductility. However, the complex microstructural evolutions during thermo-mechanical processing and the influence of constituent phases on mechanical properties have not been fully understood. In this study, the formation process of multi-phased microstructures in a low alloy steel during intercritical annealing and subsequent partitioning heat-treatment were systematically investigated. The phase fractions of ferrite, martensite, and retained austenite were found to change significantly with increasing holding time at lower temperature. Newly formed ferrite was observed to transform from austenite through massive or bainitic transformation, resulting in different types of ferrite in the final microstructures. The presence of retained austenite was attributed to interstitial carbon diffusion, leading to improved tensile elongation and TRIP effect during deformation. The best strength-ductility balance was achieved with the shortest heat-treatment at lower temperature.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2023)
Article
Nanoscience & Nanotechnology
Avala Lavakumar, Myeong-heom Park, Sukyoung Hwang, Hiroki Adachi, Masugu Sato, Ranjit Kumar, Mitsuhiro Murayama, Nobuhiro Tsuji
Summary: Deformation-induced martensitic transformation is a crucial phenomenon for achieving both high strength and large ductility in low alloy multi-phase steels. The transformation induced plasticity (TRIP) effect, which involves the phase transformation from austenite to martensite during deformation, can significantly enhance the strain hardening ability. The mechanical stability of austenite against martensitic transformation is influenced by the surrounding phases, but the details are still unclear.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2023)
Article
Materials Science, Multidisciplinary
Yan Chong, Jangho Yi, Guanyu Deng, Nobuhiro Tsuji
Summary: The aging behavior of Ti-1.0 wt pct Fe alloy was studied in this research, focusing on microstructural modifications within the beta grains. At lower aging temperatures, omega(ath) precipitates gradually decreased and were replaced by alpha(s) precipitates. At higher aging temperatures, alpha(s) precipitates increased in size while their volume fraction decreased, indicating a partial alpha to beta reverse phase transformation. The presence of omega(ath) promoted a homogeneous precipitation behavior of alpha(s) precipitates, leading to the formation of plate-shaped alpha(s) precipitates with multiple crystallographic variants.
METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE
(2023)
Article
Nanoscience & Nanotechnology
Wu Gong, Takuro Kawasaki, Ruixiao Zheng, Tsuyoshi Mayama, Binxuan Sun, Kazuya Aizawa, Stefanus Harjo, Nobuhiro Tsuji
Summary: The deformation behavior of a commercial AZ31 magnesium alloy was studied during uniaxial compression at 21 K and 298 K using in-situ neutron diffraction. Decreasing the deformation temperature led to a slight increase in yield stress, but a remarkable enhancement in both the fracture stress and fracture strain. The low temperature sensitivity of the {10 (1) over bar2} extension twinning resulted in the slight increase in yield stress. At 21K, basal slip was suppressed, while extension twinning was promoted, leading to a higher twin volume fraction. The suppression of {10 (1) over bar1}-{10 (1) over bar2} double twinning in the late stage of deformation was considered to be the reason for the delayed fracture at 21 K.
SCRIPTA MATERIALIA
(2023)
Article
Nanoscience & Nanotechnology
Yan Chong, Reza Gholizadeh, Kaichi Yamamoto, Nobuhiro Tsuji
Summary: The coarse lamellar microstructure of as-cast alpha+beta titanium alloys can be effectively refined by boron additions, which has mainly been attributed to the precipitation of TiB whiskers that pin the growth of prior beta grains. We report an alternative mechanism of colony refinement in Ti-6Al-4V alloy containing trace amounts of boron solutes (0.02 wt.%). Using atom probe tomography, it is discovered for the first time that boron solutes segregate at the alpha/beta phase boundaries, due to its negligible solubilities in both alpha and beta phases. These segregated boron solutes at the alpha/beta phase boundaries restrict an easy growth of grain boundary alpha, and in turn promote the nucleation of more grain boundary alpha variants that serve as nucleation sites of alpha colonies. Hence, the colony size can be substantially refined without the formation of TiB whiskers that could be harmful to the ductility of the material.
SCRIPTA MATERIALIA
(2023)
Article
Nanoscience & Nanotechnology
Avala Lavakumar, Shuhei Yoshida, Jesada Punyafu, Shiro Ihara, Yan Chong, Hikaru Saito, Nobuhiro Tsuji, Mitsuhiro Murayama
Summary: The study focuses on the influence of grain size and temperature on the mechanical properties of equiatomic FeCoNi alloy. Different grain sizes ranging from ultra-fine to coarse were achieved by high-pressure torsion and annealing. The results show that the tensile yield strength is affected by temperature and grain size, and the grain boundary strength remains constant while the friction stress increases at lower temperature. At cryogenic temperature, the presence of nano twinning contributes to the enhancement of strength and ductility in addition to dislocation slip.
SCRIPTA MATERIALIA
(2023)
Article
Nanoscience & Nanotechnology
Elis Sjogren-Levin, Wolfgang Pantleon, Aylin Ahadi, Zoltan Hegedus, Ulrich Lienert, Nobuhiro Tsuji, Kei Ameyama, Dmytro Orlov
Summary: In situ X-ray diffraction was used to study the tensile deformation behavior of HS nickel, which consists of a continuous network of fine grains and islands of coarse grains. A separation algorithm was developed to analyze the X-ray diffraction signals from coarse and fine grains separately. Line profile analysis was used to examine the evolution of local stresses and microstrains in different grain fractions. The study identified several stages during yielding and the onset of plastic deformation in HS nickel, and found that the plastic deformation of coarse grains is constrained by the network of fine grains.
SCRIPTA MATERIALIA
(2023)
Article
Materials Science, Multidisciplinary
Wenqi Mao, Si Gao, Wu Gong, Yu Bai, Stefanus Harjo, Myeong-Heom Park, Akinobu Shibata, Nobuhiro Tsuji
Summary: This study performed tensile deformation with in situ neutron diffraction measurement on an Fe-24Ni-0.3C (wt.%) TRIP-assisted austenitic steel, and proposed an analysis method based on stress partitioning and phase fractions measured by neutron diffraction. The results showed that both the transformation rate and the phase stress borne by the deformation-induced martensite played important roles in the global tensile properties of the material. The proposed decomposition analysis method could be widely applied to investigating mechanical behavior of multi-phase alloys exhibiting the TRIP phenomenon.
Article
Nanoscience & Nanotechnology
Qian He, Shuhei Yoshida, Nobuhiro Tsuji
Summary: This study reports the characteristic strengthening mechanisms of HfNbTaTi, HfNbTiZr, HfNbTi, HfTaTi, and NbTiZr equi-atomic refractory medium entropy alloys (RMEAs). The alloys were processed to obtain microstructures with varying grain sizes and their mechanical properties were evaluated. The low elastic modulus of the RMEAs was found to be the reason for their small slopes of the Hall-Petch relationships and weak grain refinement strengthening. Moreover, the high friction stresses of the RMEAs were attributed to the interaction between severe lattice distortion and elastic field of edge dislocations.
SCRIPTA MATERIALIA
(2023)
Article
Nanoscience & Nanotechnology
Wenqi Mao, Si Gao, Wu Gong, Stefanus Harjo, Takuro Kawasaki, Nobuhiro Tsuji
Summary: In this study, an in-situ neutron diffraction and digital image correlation measurement were conducted on an ultrafine grain stainless steel with a large Luders band deformation to assess the individual contributions of the austenite matrix and deformation-induced martensite to strain hardening during band propagation. The quantitive analysis revealed that the strain hardening of the austenite matrix was insufficient to maintain uniform deformation when the flow stress increased due to the ultrafine grain structure. The strain hardening required for Luders band propagation was primarily provided by martensite formation and the high internal stress within it.
SCRIPTA MATERIALIA
(2023)
