オーステンパ処理球状黒鉛鋳鉄の長寿命域における疲労強度

概要

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This paper describes the effects of shot peening and artificial small defects on the fatigue strength of austempered ductile cast iron (ADI). The fatigue strength of smooth specimens was increased by shot peening in a short life regime and the increments reached about 33 and 29% at 10^5 and 10^6 cycles, respectively. The improvement of fatigue strength, however, almost disappeared in a long life regime of 10^8 cycles. Small drilling holes were used as artificial defects. The diameters of the holes were 0.1,0.2,0.3 and 0.4mm and their depths were almost the same as the diameter. The fatigue strength of the specimens with a 0.1mm drilling hole did not decrease when compared with that of the smooth specimens, but the fatigue strengths of the specimens with 0.2〜0.4mm drilling holes decreased. The experimental results of the specimens with 0.2〜0.4mm drilling holes were consistent with the predlction by Murakami's √<area> parameter model. The maximum size, (√<area>)_<max>, of the pre-existent defects in ADI was equivalent to the defect of the specimen with a 0.1mm drilling hole and was estimated to be about 90 μm by the above model.
一般社団法人日本機械学会の論文
1997-06-25