Assessment of hydrogen embrittlement behavior in Al-Zn-Mg alloy through multi-modal 3D image-based simulation

Fujihara, Hiro*; Toda, Hiroyuki*; Ebihara, Kenichi; Kobayashi, Masakazu*; Mayama, Tsuyoshi*; Hirayama, Kyosuke*; Shimizu, Kazuyuki*; Takeuchi, Akihisa*; Uesugi, Masayuki*

International Journal of Plasticity, 174, p.103897_1 - 103897_22, 2024/03

https://doi.org/10.1016/j.ijplas.2024.103897

Hydrogen(H) embrittlement in high-strength aluminum(Al) alloys is a crucial problem. H accumulation at the interface of precipitates in Al alloy is considered to cause embrittlement. However, there is no quantitative knowledge regarding the interaction between H distribution and stress field near cracks. In this study, using a multi-modal three-dimensional image-based simulation combining the crystal plasticity finite element method and H diffusion analysis, we tried to capture the stress distribution near the crack, its influence on the H distribution, and the probability of crack initiation in the experimental condition. As a result, it was found that grain boundary cracks transition to quasi-cleavage cracks in the region where the cohesive energy of the semi-coherent interface of MgZn precipitates decreases due to H accumulation near the tip. We believe the present simulation method successfully bridges nanoscale delamination and macroscale brittle fracture.

Effect of extrusion ratio in hot-extrusion on kink deformation during compressive deformation in an Mg/LPSO dual-phase magnesium alloy monitored by neutron diffraction

Harjo, S.; Gong, W.; Aizawa, Kazuya; Kawasaki, Takuro; Yamasaki, Michiaki*; Mayama, Tsuyoshi*; Kawamura, Yoshihito*

Materials Transactions, 64(4), p.766 - 773, 2023/02

https://doi.org/10.2320/matertrans.MT-MD2022004

Deformation mechanisms of AZ31 alloy at cryogenic temperature investigated by in-situ neutron diffraction

Gong, W.; Harjo, S.; Mayama, Tsuyoshi*; Kawasaki, Takuro; Aizawa, Kazuya; Sun, B.*; Tsuji, Nobuhiro*

no journal, , 

In situ neutron diffraction experiments at cryogenic temperature was performed to investigate the temperature dependence of deformation behavior and corresponding activities of deformation mechanisms in a commercial AZ31 Mg alloy. The stress-strain curve at 21K showed slightly higher macroscopic yield stress but remarkably higher fracture stress and strain than that of room temperature. The enhancement of extension twinning and suppression of contraction twinning at cryogenic temperature are considered to be the reasons for improving the corresponding macroscopic strength and ductility in the commercial AZ31 alloy.

In-situ neutron diffraction study of cryogenic deformation behavior in AZ31 magnesium alloy

Gong, W.; Harjo, S.; Mayama, Tsuyoshi*; Kawasaki, Takuro; Aizawa, Kazuya; Tsuji, Nobuhiro*

no journal, ,