Effect of grain size on ultrasonic fatigue properties of Ni-base super alloy inconel 718

Norio Kawagoishi, Eiji Maemura, Qiang Chen, Masahiro Goto, Kazuhiro Morino

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Abstract

Ultrasonic fatigue tests of plain specimens with different grain sizes were carried out for Ni-base super alloy, Inconel 718, in ambient air in order to investigate the effect of grain size on fatigue properties. Fatigue strength was increased with decrease in grain size. The increase in fatigue strength by refining grain size was mainly caused by the suppression of crack initiation. That is, the effect of grain size on crack growth rate was hardly recognized, though crack morphology was rougher in the specimen of larger grain, meaning that the crack growth in the large-grained specimens was suppressed by roughness induced crack closure. On the other hand, however, more flat facets caused by twin boundary cracking were observed in the large-grained specimens, which inversely led to crack growth acceleration.

Original languageEnglish
Pages (from-to)1000-1005
Number of pages6
JournalNihon Kikai Gakkai Ronbunshu, A Hen/Transactions of the Japan Society of Mechanical Engineers, Part A
Volume74
Issue number7
DOIs
Publication statusPublished - Jul 2008

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All Science Journal Classification (ASJC) codes

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

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