A study of fatigue fracture properties of high strength notched steel in high cycle fatigue region with special focus on the statistical variation of the local fatigue strength at the Notch Bottom

Kengo Fukazawa, Masaki Shibuya, Tomonaga Okabe, Masao Shimizu, Kazuhiro Kawasaki

Research output: Contribution to journalArticlepeer-review

Abstract

This study was conducted to examine how and why a difference of fatigue strengths between unnotched and notched specimens, in terms of maximum stress amplitude at the notch bottom, depends on the change of hardness level in steel. As a result, the local fatigue strength of the notch bottom in the notched specimen became higher than that of the un-notched one with increase of notch sharpness and this was remarkable in high strength steel. This is because the transition of the fatigue fracture mode occurs from a slip induced crack initiation mode to a defect controled one with increasing hardness in steel. In addition, using a new experimental approach combined with a simulation technique based on the concept of risk competition of defects, a computer simulation was conducted on an effect of inclusion on the local fatigue strength at the notch bottom of high strength steel. It was clarified that the difference of fatigue strength between notched and un-notched specimens in high strength steel was caused by the statistical variation of the largest inclusion size contained in the critical volume at the notch bottom.

Original languageEnglish
Pages (from-to)623-629
Number of pages7
JournalNihon Kikai Gakkai Ronbunshu, A Hen/Transactions of the Japan Society of Mechanical Engineers, Part A
Volume71
Issue number4
DOIs
Publication statusPublished - 2005 Apr
Externally publishedYes

Keywords

  • Computer Simulation
  • Fatigue
  • Fracture Mechanism
  • Hardness
  • High Strength Steel
  • Inclusion

ASJC Scopus subject areas

  • Materials Science(all)
  • Mechanics of Materials
  • Mechanical Engineering

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