Effects of residual stress on hydrogen embrittlement of a stretch-formed tempered martensitic steel sheet

Nishimura Hayato, Hojo Tomohiko, Ajito Saya, Shibayama Yuki, Koyama Motomichi, Saitoh Hiroyuki, Shiro Ayumi, Yasuda Ryo, Shobu Takahisa, Akiyama Eiji

研究成果: Article査読

抄録

The effects of residual stress on the hydrogen embrittlement behavior of a tempered martensitic steel sheet with 1-GPa-class tensile strength stretch-formed by a hemisphere punch simulating press-formed automotive structural parts were investigated. Cracking on the stretch-formed specimen induced by potentiostatic hydrogen charging was initiated in the foot of the impression of the specimen and propagated to the radial direction both toward the hillside and the plain. The mixture of quasi cleavage and intergranular fractures were observed whole through the fracture surface. Residual stress in the stretch-formed specimens was analyzed by using energy-dispersive X-ray diffraction method utilizing the synchrotron X-ray radiation at SPring-8. In addition, stress and plastic strain distributions in the specimen were analyzed by using Finite Element Method (FEM). These analyses depicted that the high tensile stress in the circumferential direction was in the foot of the impression, corresponding to the direction of the crack growth. The FEM analysis revealed that the high triaxial stress was in the foot suggesting accumulation of hydrogen. It was considered that the preferential crack initiation at the foot was promoted by the high residual stress in the circumferential direction and the hydrogen accumulation due to stress-induced diffusion.

本文言語English
ページ(範囲)1170-1178
ページ数9
ジャーナルIsij International
61
4
DOI
出版ステータスPublished - 2021

ASJC Scopus subject areas

  • 材料力学
  • 機械工学
  • 金属および合金
  • 材料化学

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