三種類の球状黒鉛鋳鉄の低サイクル疲労における破壊起点

概要

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In this study, plastic-strain-controlled low cycle fatigue tests were carried out using cylindrical specimens of three kinds of spherodial graphite cast iron (ferritic ; FDI, pearlitic : PDI, and austempered ; ADI). In order to specify the kind of defect in fracture origin, a fracture section was observed by using SEM. As a result, the fracture starts at microshrinkages that exist on the neighboring surface in these materials. The length of microshrinkages projected on the surface ranges from 100 to 800 μm. Also, there is no precise relationship between the fatigue life and the observed shape of microshrinkages. In the specimen with a small blind hole having 0.4 mm diameter (the depth of it equals the diameter), the fracture starts at the hole. However, in the specimen with a small blind hole of 0.2 mm diameter, it starts at microshrinkages.
一般社団法人日本機械学会の論文
1999-02-25