IP処理によるSMF 3種焼結材の回転曲げ疲労におけるき裂の発生および初期き裂伝ぱ過程

概要

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Rotating bending fatigue tests of plain specimens were carried out on HIP'ed SMF3035(density :7.83 g/cm^3) and CIP'ed SMF3020 (density : 7.09 g/cm^3) specimens, in order to investigate the effect of sintered density on the characteristics of the initiation and propagation of a crack through successive observations of the plastic replica method. The following main results were obtained. 1) σ_<wo>/σ_s of HIP'ed SMF3035 is 0.45 and CIP'ed SMF3020 is 0.39. 2) When σ> σ_<wo>, in HIP'ed SMF3035 a crack appears in an area having a finite size after some stress repetitions and in CIP'ed SMF3020 a crack appears at the edge of the defect just after stress repetitions. 3) When σ=σ_<wo>, nonpropagating microcracks are observed on plain specimens of both materials after N-1×10^7 under a metallurgical microscope. Therefore, the fatigue limit of plain specimens is determined by the limiting condition for propagation of a microcrack.
社団法人日本機械学会の論文
1992-09-25