Effect of strain rate on the hydrogen embrittlement property of ultra high-strength low alloy TRIP-aided steel

Tomohiko Hojo, Riko Kikuchi, Hiroyuki Waki, Fumihito Nishimura, Yuko Ukai, Eiji Akiyama

Research output: Contribution to journalReview articlepeer-review

10 Citations (Scopus)

Abstract

The effect of strain rate on the hydrogen embrittlement property of an ultra high-strength TRIP-aided bainitic ferrite (TBF) steel with bainitic ferrite matrix was investigated to clarify the correlation between the transformation behavior of retained austenite and the hydrogen embrittlement fracture behavior of the TBF steel. Tensile tests were carried out at the strain rates between 5.56 × 10−6 and 2.78 × 10−2/s without and with hydrogen charging. Hydrogen analysis after tensile tests was conducted by using thermal desorption spectroscopy (TDS). Fracture strain decreased with decreasing the strain rate due to the hydrogen absorption to the TBF steel although fracture strain without hydrogen charging slightly increased with decreasing the strain rate. However, it was observed that transformation behavior of retained austenite was hardly changed by the hydrogen absorption and the change in the strain rate. When tensile test was carried out to the TBF steel at the slow strain rate with hydrogen charging, fracture surface of quasi cleavage fracture containing flat facet, which was fractured transformed martensite, was obtained and the crack perpendicular to the tensile direction was observed near transformed martensite. It was considered that the decrease in the resistance to hydrogen embrittlement of the TBF steel tensile tested at the slow strain rate was attributed to the initiation of flat facet and the hydrogen concentration at the crack tip due to the hydrogen diffusion from transformed martensite during tensile testing at slow strain rate.

Original languageEnglish
Pages (from-to)751-759
Number of pages9
JournalIsij International
Volume58
Issue number4
DOIs
Publication statusPublished - 2018

Keywords

  • High-strength steel
  • Hydrogen embrittlement
  • Retained austenite
  • Strain rate
  • TRIP

ASJC Scopus subject areas

  • Mechanics of Materials
  • Mechanical Engineering
  • Metals and Alloys
  • Materials Chemistry

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