High cycle fatigue strength of 2.25Cr-1Mo steel under repeated two-step variable amplitude loading

Tatsuro Nakazawa, Takeshi Ogawa, Kenichi Sakaue

Research output: Contribution to journalArticle

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Abstract

Ultrasonic fatigue tests were conducted for medium strength steel, 2.25Cr-1Mo, under constant amplitude loading and repeated two-step variable amplitude loading conditions to evaluate the effect of loading conditions on fracture behavior. Most of the specimens were broken from an inclusion on the specimen surface. Cumulative damage value, D, calculated by Miner's rule, which ignored the damage by cyclic loading below fatigue limit, exhibited inappropriate prediction of fatigue life. The D values calculated by modified Miner's rule remarkably varied by the conditions of the repeated two-step variable amplitude loading. In some cases, specimen was not broken until D became larger than 60. Observations at fracture origin using replication technique revealed that stress amplitude below fatigue limit increased the resistance of fatigue crack initiation and/or growth. Mechanisms of these behaviors were discussed in detail.

Original languageEnglish
Pages (from-to)885-889
Number of pages5
JournalZairyo/Journal of the Society of Materials Science, Japan
Volume60
Issue number10
DOIs
Publication statusPublished - 2011 Nov 7

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Keywords

  • 2.25Cr-1Mo steel
  • Crack growth
  • Cycle ratio
  • Fatigue
  • Fatigue life
  • Inclusion
  • Variable amplitude loading

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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