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
Materials Science, Multidisciplinary
Tingshu Chen, Takahiro Chiba, Motomichi Koyama, Eiji Akiyama, Kenichi Takai
Summary: Intergranular fracture is the primary mode of fracture in lath martensitic steels with a significant amount of hydrogen. With a reduction in hydrogen content, plasticity plays a significant role in the intergranular fracture, leading to intergranular-like fracture. Intergranular fracture occurs in the macroscopically elastic regime, while intergranular-like fracture involves plasticity evolution, resulting in the formation of nano-voids and tear ridges.
METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE
(2022)
Article
Metallurgy & Metallurgical Engineering
Naoki Uemura, Takahiro Chiba, Kenichi Takai
Summary: The dependence of crack initiation sites and main factors causing hydrogen embrittlement fracture on carbide precipitation states has been investigated for tempered martensitic steels with the same tensile strength of 1450 MPa. Different carbide precipitation states changed the crack initiation sites and fracture morphologies involved in hydrogen embrittlement depending on mechanical factors such as stress and strain and micro structural factors.
TETSU TO HAGANE-JOURNAL OF THE IRON AND STEEL INSTITUTE OF JAPAN
(2023)
Article
Nanoscience & Nanotechnology
Amir Falekari, Hamid Reza Jafarian, Ali Reza Eivani, Mahdi Habibnejad-korayem, Akbar Heidarzadeh
Summary: Thick tempered martensitic steel plates were friction stir processed to form finer martensite phase and ferrite, leading to increased hardness. However, this process reduced the tensile strength and elongation, resulting in brittle fractured surfaces.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2022)
Article
Materials Science, Multidisciplinary
Virginia Bertolo, Quanxin Jiang, Ursa Tiringer, Carey L. Walters, Jilt Sietsma, Vera Popovich
Summary: In this study, the effects of through-thickness microstructure, notch orientation, and crack tip constraint on the cleavage fracture micromechanisms of an 80-mm-thick high-strength steel were assessed. The results showed that the notch orientation did not play a role, while Nb-rich inclusions acted as weak microstructural links in the steel.
JOURNAL OF MATERIALS SCIENCE
(2022)
Article
Engineering, Mechanical
Molin Su, Lianyong Xu, Chao Feng, Yongdian Han, Lei Zhao, Guangchun Xiao
Summary: This study designed different types of samples to distinguish physically short cracks and microstructurally short cracks based on crack growth rate and length. A piecewise model was proposed to describe the entire short crack propagation.
FATIGUE & FRACTURE OF ENGINEERING MATERIALS & STRUCTURES
(2022)
Article
Materials Science, Multidisciplinary
Takuya Yamamoto, Yuan Wu, Kiyohiro Yabuuchi, Jack Haley, Kenta Yoshida, Akihiko Kimura, G. Robert Odette
Summary: The microstructural evolutions of two variants of the F82H 8 wt%Cr tempered martensitic steel under dual ion irradiations have been investigated. The study focuses on the effects of displacements per atom (dpa) and the helium/dpa ratio (He/dpa) on cavity evolution and void swelling. The analysis suggests that local microstructural variations contribute to the observed scatter in the data, and the highest void swelling data provides the most appropriate estimate of swelling for fusion neutron irradiation conditions. The dose dependence of void swelling can be described by an incubation dpa and a post-incubation swelling rate, which both decrease with increasing He/dpa.
JOURNAL OF NUCLEAR MATERIALS
(2023)
Article
Physics, Multidisciplinary
Xiao Zhou, Ali Tehranchi, William A. Curtin
Summary: The urgent need for clean energy and the exceptional promise of hydrogen as a clean fuel are driving the development of new metals resistant to hydrogen embrittlement. New experiments on fcc high entropy alloys suggest a paradox where these alloys absorb more H than traditional metals like Ni or SS304 while being more resistant to embrittlement, and a new theory has been proposed to rationalize this phenomenon. The theory has been able to quantitatively predict the hydrogen concentration at which embrittlement occurs and sheds light on the resistance mechanisms of different alloys.
PHYSICAL REVIEW LETTERS
(2021)
Article
Chemistry, Physical
Jie Shi, Wenchao Yu, Ting Sun, Le Xu, Xiaoyuan Li, Maoqiu Wang
Summary: The crack growth rate in two high strength martensitic steels with different Mo contents was investigated. It was observed that the crack growth rate increased and the values of stress intensity factors KIH and KImax decreased with the increase of hydrogen concentration. The steel with higher Mo content exhibited lower crack growth rate, which may be attributed to the presence of more nano-sized precipitates that can trap hydrogen and mitigate its deleterious effects.
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
(2023)
Article
Materials Science, Multidisciplinary
Takuya Yamamoto, G. Robert Odette
Summary: This study utilizes the UCSB database on cavity evolution in 9-12Cr tempered martensitic steels to derive a model for the void volume fraction as a function of displacements per atom and transmutant helium concentrations. The model shows that the incubation dose and post-incubation growth rate decrease with increasing helium/dpa, and the dpai is lower for ISHI neutron irradiations. The post-incubation fv' data have a common empirical curve shape, and fv' can be predicted based on a physical model of defect partitioning.
JOURNAL OF NUCLEAR MATERIALS
(2023)
Article
Materials Science, Multidisciplinary
L. Cho, P. E. Bradley, D. S. Lauria, M. L. Martin, M. J. Connolly, J. T. Benzing, E. J. Seo, K. O. Findley, J. G. Speer, A. J. Slifka
Summary: This study provides a detailed characterization of the microstructures and dislocation characteristics beneath hydrogen-induced quasi-cleavage fracture features of an as-quenched martensitic steel. The dominant fracture mode in the hydrogen-affected zones was found to be quasi-cleavage fracture, involving significant plasticity. The sizes, orientations, and boundaries of the martensite constituents influenced the surface morphologies of the quasi-cleavage fractures.
Article
Engineering, Manufacturing
Heather A. Murdoch, Daniel M. Field, Benjamin A. Szajewski, Levi D. Mcclenny, Andrew Garza, Berend C. Rinderspacher, Mulugeta A. Haile, Krista R. Limmer
Summary: A simple Gaussian process regressor model was used to predict the hardness and toughness response of tempered martensitic steels, showing increased accuracy compared to linear regression. The analysis revealed that tempering temperature and carbon content were the most important input features affecting the model's performance. The SHAP analysis demonstrated the complex relationships between alloy composition and mechanical properties captured by machine learning approaches.
INTEGRATING MATERIALS AND MANUFACTURING INNOVATION
(2023)
Article
Multidisciplinary Sciences
Niyanth Sridharan, Maxim Gussev, Sudarsanam Babu
Summary: Nature-inspired hierarchical steels were successfully fabricated using additive manufacturing to mimic the structure and deformation mechanisms found in natural materials, resulting in improved strength and ductility. The study distinguished itself by leveraging AM and physical metallurgy concepts to trigger cascading deformation in a single sample, demonstrating the potential of using AM to fabricate structures that emulate the flexibility in mechanical properties of natural materials and adapt to in-service conditions.
SCIENTIFIC REPORTS
(2021)
Article
Mechanics
Ross J. Stewart, Naveen Prakash
Summary: This study fills the gap in understanding the fragmentation of strengthened glass articles. It investigates glass plates with parabolic residual stress profiles, including deep chemically strengthened glass and tempered glass. The study introduces a parameter defining the onset of fragmentation susceptibility and an equation predicting the number of fragments per sheet area. This equation can be used to analyze experimental data and determine the frangibility limit and dynamic toughness, which are otherwise difficult to measure. Future research will explore the applicability of this theoretical framework to stress profiles of different shapes.
ENGINEERING FRACTURE MECHANICS
(2023)
Article
Nanoscience & Nanotechnology
Hiroyuki Dannoshita, Hiroshi Hasegawa, Sho Higuchi, Hiroshi Matsuda, Wu Gong, Takuro Kawasaki, Stefanus Harjo, Osamu Umezawa
Summary: The role of dislocation structure on the work-hardening behavior during tensile deformation of quenched and tempered martensite was investigated. The study found that the elastic limit is not always dependent on the total dislocation density of martensite, and the dislocation arrangement parameter plays a guiding role in the strength increase of martensitic steels.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2022)
Article
Materials Science, Multidisciplinary
Yutao Zhou, Motomichi Koyama, Tomohiko Hojo, Saya Ajito, Eiji Akiyama
Summary: In this study, the temperature dependence of microstructure and damage evolution in medium Mn steel was investigated. The results showed that deformation temperatures had a significant impact on the flow behavior, work hardening rate, and mechanical properties of the steel. Deformation-induced martensite acted as the initiation site of damage, and the critical strain and probability of damage initiation decreased with decreasing deformation temperature. Furthermore, the decrease in temperature deteriorated the micro-damage arrestability of ferrite, resulting in a transition from ductile to quasi-cleavage fractures.
METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE
(2023)
Article
Nanoscience & Nanotechnology
Kazuho Okada, Akinobu Shibata, Taisuke Sasaki, Hisashi Matsumiya, Kazuhiro Hono, Nobuhiro Tsuji
Summary: This study aimed to improve the resistance against hydrogen embrittlement by increasing the concentration of carbon segregated at prior austenite grain boundary (PAGB), XPAGB, in low-carbon martensitic steels. The specimens with and without carbon segregation treatment (Non-seg and Seg specimens, respectively) had similar microstructures, except for higher XPAGB in the Seg specimen. The Seg specimen exhibited higher maximum stress and smaller fraction of intergranular fracture surface under hydrogen-charged conditions, indicating that segregated carbon suppressed hydrogen accumulation and increased cohesive energy of PAGB.
SCRIPTA MATERIALIA
(2023)
Article
Chemistry, Physical
Rama Srinivas Varanasi, Motomichi Koyama, Hiroyuki Saitoh, Reina Utsumi, Toyoto Sato, Shin-ichi Orimo, Eiji Akiyama
Summary: The phase transformations and microstructure changes during the depressurization of non-hydrogenated and hydrogenated Fe-Mn-Si-Cr alloy were investigated. Understanding the effects of hydrogenation on the stability of the austenite phase in Fe-based alloys is crucial.
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
Materials Science, Multidisciplinary
Hao Luo, Van Hoang Nguyen, Kazuhiro Gotoh, Saya Ajito, Tomohiko Hojo, Yasuyoshi Kurokawa, Eiji Akiyama, Noritaka Usami
Summary: This study investigates the effect of post-oxidizing treatment (POT) on the structural, optical, and passivation performances of titanium oxide coated crystalline Si (c-Si) heterostructures prepared by the solution process. The results show that POT improves the passivation performance by oxidizing the TiOx film, c-Si surface, and forming POx.
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
Materials Science, Multidisciplinary
Akinobu Shibata, Goro Miyamoto, Shigekazu Morito, Akiko Nakamura, Taku Moronaga, Houichi Kitano, Ivan Gutierrez-Urrutia, Toru Hara, Kaneaki Tsuzaki
Summary: In this study, the substructures and crystallographic features of as-quenched lath martensite in interstitial-free (IF) steel and low-carbon steel (0.2C steel) were analyzed using advanced microscopy techniques. The study revealed differences in the morphology and habit plane orientation between the two types of steel. Dislocation structures, cementite formation, and carbon segregations were observed, indicating significant changes in the substructure during quenching. Based on the experimental results, the researchers discussed the origin of the substructures and crystallographic features of lath martensite.
Article
Chemistry, Physical
Akinobu Shibata, Ivan Gutierrez-Urrutia, Akiko Nakamura, Kazuho Okada, Goro Miyamoto, Yazid Madi, Jacques Besson, Toru Hara, Kaneaki Tsuzaki
Summary: This study investigated the three-dimensional propagation behavior of hydrogen-related intergranular cracks in martensitic steel. X-ray computed tomography revealed that cracks in hydrogen-charged specimens were more continuous. Furthermore, crack-tip blunting and ductile rupture of un-cracked ligaments were associated with specific prior austenite grain boundary (PAGB) segments in the uncharged specimen.
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
(2023)
Article
Materials Science, Multidisciplinary
Saya Ajito, Tomohiko Hojo, Motomichi Koyama, Sachiko Hiromoto, Eiji Akiyama
Summary: The environment-assisted cracking behavior of AZ31 magnesium alloy was studied through tensile tests in a Na2B4O7·10H2O solution containing NH4SCN and in air at cathodic and corrosion potentials. Mechanical properties of AZ31 were unaffected by the environment at an initial strain rate of 10-4s-1, but degraded in the solution at an initial strain rate of 10-6s-1. Higher potentials resulted in smaller total elongation, while positive potential shift increased the average hydrogen absorption rate. These findings indicate that environment-assisted cracking becomes more severe under relatively high potential due to corrosion and enhanced hydrogen absorption.
Article
Nanoscience & Nanotechnology
Yutao Zhou, Tomohiko Hojo, Motomichi Koyama, Saya Ajito, Eiji Akiyama
Summary: Hydrogen and deformation temperature have significant effects on micro-damage evolution and fracture behavior of TRIP-aided steel. Hydrogen uptake increases micro-damage density and changes fracture mode at different deformation temperatures.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(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)
