Comparison of hydrogen embrittlement resistance of high strength steel sheets evaluated by several methods

Shusaku Takagi, Yukito Hagihara, Tomohiko Hojo, Wataru Urushihara, Kaoru Kawasaki

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

Applications of ultra high strength steel sheets to automotive body have been expanding year after year. Hydrogen embrittlement (HE) is one of the problems of ultra high strength steels. Various methods are used as the evaluation method of HE resistance. In this study, the critical HE conditions obtained by SSRT, CSRT and 4-point bending test were compared by using the same materials, which have tempered martensite microstructure with the composition of a SCM435 or an V added steel with many hydrogen trapping precipitations. Specimens were charged with hydrogen by the cathodic charging method. The specimen used in the SSRT and the CSRT was machined with notches on the both sides of a parallel part and the stress concentration factor (Kt) of the specimens was 4.26 or 1.76. The specimen used in the 4-point bending test was coupon shape. The critical HE conditions evaluated with the average applied stress and the average hydrogen content of the specimen were different depending on the test methods. HE conditions were also evaluated with the local stress and the local accumulated diffusible hydrogen content at the fracture initiation point. The critical condition evaluated by the 4-point bending test was located in the higher stress and higher hydrogen content region compared with the critical conditions obtained by the CSRT and the SSRT.

Original languageEnglish
Pages (from-to)1315-1321
Number of pages7
JournalTetsu-To-Hagane/Journal of the Iron and Steel Institute of Japan
Volume100
Issue number10
DOIs
Publication statusPublished - 2014 Jan 1
Externally publishedYes

Keywords

  • 4-point bending test
  • Conventional strain rate test
  • Delayed fracture
  • Local diffusible hydrogen content
  • Local stress
  • Slow strain rate test

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Physical and Theoretical Chemistry
  • Metals and Alloys
  • Materials Chemistry

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