Effects of aluminum on delayed fracture properties of ultra high strength low alloy TRIP-aided steels

Tomohiko Hojo, Koh Ichi Sugimoto, Youichi Mukai, Shushi Ikeda

Research output: Contribution to journalArticlepeer-review

73 Citations (Scopus)


To improve the delayed fracture strength of ultra high-strength low alloy TRIP-aided steels with bainitic ferrite matrix (TBF steels), the effects of aluminum content on hydrogen absorption behavior and delayed fracture properties of 0.2%C-0.2-1.5%Si-1.5%Mn TBF steel were investigated. When aluminum was added to the TBF steel, the diffusible hydrogen increased. It was expected that the hydrogen was charged not only in retained austenite films but also on lath boundary. Delayed fracture strength of TBF steels containing aluminum were significantly increased, compared with conventional TBF steel. This was mainly caused by (1) suppression of the stress-assisted martensite transformation resulting from the stabilized or carbon-enriched retained austenite, (2) hydrogen trapping to refined interlath retained austenite films and lath boundary, and (3) relaxation of localized stress concentration by TRIP effect of the retained austenite.

Original languageEnglish
Pages (from-to)824-829
Number of pages6
JournalIsij International
Issue number6
Publication statusPublished - 2008
Externally publishedYes


  • Aluminum
  • Delayed fracture
  • Hydrogen
  • Retained austenite
  • TRIP-aided steel
  • Ultra high strength steel

ASJC Scopus subject areas

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


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