微粒子衝突処理を施した高炭素クロム軸受鋼の疲労挙動

概要

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Cantilever-type rotary bending fatigue tests were conducted on high carbon chromium steel in laboratory air at room temperature. Three kinds of specimens were prepared, i. e. fine particle bombarded (FPB), shot peened (SP) and untreated. Each specimen showed a step-wise S-N curve, but the transition stress below which subsurface crack initiation took place became higher in the surface-treated specimens than in the untreated specimen. The effect of the surface treatment appeared at stress levels above the transition stress of the untreated specimen, while it disappeared at stress levels below that stress. Subsurface crack initiation seemed to occur at the location where the superposition stress that was the sum of the applied tensile stress and the residual stress was the maximum. A fish-eye was always observed with an inclusion from which a crack initiated. Although the features of fish-eyes were somewhat different in three kinds of specimens, the fatigue lives were almost the same, indicating that the fatigue strength was not influenced by the surface treatment when subsurface crack initiation occurred. Regardless of surface treatment, fatigue life tended to increase with decreasing the stress intensity factor obtained by assuming an inclusion as a crack.
一般社団法人日本機械学会の論文
2002-03-25