Effects of alloying elements addition on delayed fracture properties of ultra high-strength trip-aided martensitic steels

Tomohiko Hojo, Junya Kobayashi, Koh Ichi Sugimoto, Akihiko Nagasaka, Eiji Akiyama

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

To develop ultra high-strength cold stamping steels for automobile frame parts, the effects of alloying elements on hydrogen embrittlement properties of ultra high-strength low alloy transformation induced plasticity (TRIP)-aided steels with a martensite matrix (TM steels) were investigated using the four-point bending test and conventional strain rate tensile test (CSRT). Hydrogen embrittlement properties of the TM steels were improved by the alloying addition. Particularly, 1.0 mass% chromium added TM steel indicated excellent hydrogen embrittlement resistance. This effect was attributed to (1) the decrease in the diffusible hydrogen concentration at the uniform and fine prior austenite grain and packet, block, and lath boundaries; (2) the suppression of hydrogen trapping at martensite matrix/cementite interfaces owing to the suppression of precipitation of cementite at the coarse martensite lath matrix; and (3) the suppression of the hydrogen diffusion to the crack initiation sites owing to the high stability of retained austenite because of the existence of retained austenite in a large amount of the martensite– austenite constituent (M–A) phase in the TM steels containing 1.0 mass% chromium.

Original languageEnglish
Article number6
JournalMetals
Volume10
Issue number1
DOIs
Publication statusPublished - 2020 Jan

Keywords

  • Hydrogen embrittlement
  • Microalloying
  • Retained austenite
  • TRIP-aided steels

ASJC Scopus subject areas

  • Materials Science(all)

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