Pre-strain effects on critical stress and hydrogen content for hydrogen-induced quasi-cleavage fracture in a TRIP-aided bainitic ferrite steel: Martensitic transformation, matrix damage, and strain aging

Bakuya Kumai, Tomohiko Hojo, Motomichi Koyama, Eiji Akiyama, Hiroyuki Waki, Akihiko Nagasaka

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)

Abstract

In this study, we characterized the details of the pre-strain effects on the microstructure, deformation/fracture behavior, and hydrogen content, with respect to the true fracture strength in the TRIP-aided bainitic ferrite steel. Three types of hydrogen embrittlement behavior were distinguished, based on pre-strain and hydrogen content. Pre-strain reduces the fraction of retained austenite, which in turn decreases the hydrogen embrittlement susceptibility when the hydrogen content is low. However, further pre-straining increases dislocation density, which has three main effects: an increase in hydrogen content, work hardening, and strain-age hardening. The increase in the hydrogen content that exceeds 4 mass ppm has been found to decrease the true fracture strength from approximately 1.5 to 1.2 GPa. The work hardening and strain-age hardening were found to increase until the critical fracture stress was achieved with respect to the strain; this led to a reduction in the elongation, particularly when the hydrogen content was high.

Original languageEnglish
Pages (from-to)27920-27928
Number of pages9
JournalInternational Journal of Hydrogen Energy
Volume45
Issue number51
DOIs
Publication statusPublished - 2020 Oct 16

Keywords

  • High-strength steel
  • Hydrogen embrittlement
  • Pre-straining
  • Retained austenite
  • Transformation-induced plasticity

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • Fuel Technology
  • Condensed Matter Physics
  • Energy Engineering and Power Technology

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