Microstructure and plasticity evolution during Lders deformation in an Fe-5Mn-0.1C medium-Mn steel

Koyama, Motomichi*; Yamashita, Takayuki*; Morooka, Satoshi; Sawaguchi, Takahiro*; Yang, Z.*; Hojo, Tomohiko*; Kawasaki, Takuro; Harjo, S.

Tetsu To Hagane, 110(3), p.197 - 204, 2024/02

https://doi.org/10.2355/tetsutohagane.TETSU-2023-038

Microstructure and plasticity evolution during Lders deformation in an Fe-5Mn-0.1C medium-Mn steel

Koyama, Motomichi*; Yamashita, Takayuki*; Morooka, Satoshi; Sawaguchi, Takahiro*; Yang, Z.*; Hojo, Tomohiko*; Kawasaki, Takuro; Harjo, S.

ISIJ International, 62(10), p.2036 - 2042, 2022/10

https://doi.org/10.2355/isijinternational.ISIJINT-2021-510

Hydrogen embrittlement of high-strength steel sheets

Hojo, Tomohiko*; Shibayama, Yuki; Ajita, Saya*; Koyama, Motomichi*; Akiyama, Eiji*

Materia, 61(7), p.413 - 418, 2022/07

https://doi.org/10.2320/materia.61.413

no abstracts in English

Effects of stress and plastic strain on hydrogen embrittlement fracture of a U-bent martensitic steel sheet

Shibayama, Yuki; Hojo, Tomohiko*; Koyama, Motomichi*; Saito, Hiroyuki*; Shiro, Ayumi*; Yasuda, Ryo*; Shobu, Takahisa; Matsuno, Takashi*; Akiyama, Eiji*

ISIJ International, 61(4), p.1322 - 1329, 2021/04

https://doi.org/10.2355/isijinternational.ISIJINT-2020-569

Hydrogen embrittlement resistance of pre-strained ultra-high-strength low alloy TRIP-aided steel

Hojo, Tomohiko*; Kumai, B.*; Koyama, Motomichi*; Akiyama, Eiji*; Waki, Hiroyuki*; Saito, Hiroyuki*; Shiro, Ayumi*; Yasuda, Ryo*; Shobu, Takahisa; Nagasawa, Akihiko*

International Journal of Fracture, 224(2), p.253 - 260, 2020/08

https://doi.org/10.1007/s10704-020-00451-5

In the study, the pre-strain effect on hydrogen embrittlement property of the ultra-high-strength transformation-induced plasticity -aided bainitic ferrite steel was investigated towards application for automobile frame parts. 3-10% tensile pre-strain suppressed hydrogen-induced mechanical degradation relative to total elongation while 12-15% pre-strained specimen did not exhibit elongation after hydrogen charging. The advantageous effect of the 3-10% pre-strain was attributed to the suppression of crack initiation related to retained austenite. The TRIP by pre-straining decreased the volume fraction of retained austenite before hydrogen charging, thereby reducing existing probabilities of preferential crack initiation sites and propagation paths. Conversely, high pre-strain such as 12-15% does not effectively work due to work hardening resulting in increases in hydrogen embrittlement susceptibility and a significant increase in hydrogen content due to the multiplication of dislocations.

Lders deformation of 5Mn-0.1C steels monitored by in-situ synchrotron X-ray diffraction under tensile loading

Morooka, Satoshi; Yamashita, Takayuki*; Koyama, Motomichi*; Shiro, Ayumi*; Tominaga, Aki; Shobu, Takahisa

no journal, , 

no abstracts in English

Low-temperature behavior analysis of 5Mn-0.1C steel by in-situ neutron diffraction

Morooka, Satoshi; Kawasaki, Takuro; Harjo, S.; Yamashita, Takayuki*; Koyama, Motomichi*; Sawaguchi, Takahiro*; Haga, Yoshinori

no journal, , 

no abstracts in English

Analysis of hydrogen diffusion behavior in a stretch-formed high strength steel with an Ir complex

Ajita, Saya*; Nishimura, Hayato*; Hojo, Tomohiko*; Koyama, Motomichi*; Fujita, Kenichi*; Kakinuma, Hiroshi*; Akiyama, Eiji*; Shibayama, Yuki

no journal, , 

no abstracts in English

Magnetic order and phase transformation in Fe-Mn-C alloy at cryogenic temperature

Morooka, Satoshi; Koyama, Motomichi*; Kawasaki, Takuro; Harjo, S.

no journal, ,