クリープおよびクリープ疲労条件下での微小き裂発生・成長と微視的ひずみ分布の関係

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Structural components operating at high temperatures in thermal and nuclear power plants are subjected to interaction of thermal fatigue and creep which results in creep-fatigue damage. In evaluating the life of those components, it is important to comprehend detailed microscopic damage evolution under creep-fatigue condition. We had observed continuously the growth and coalescence of cavity and microcrack on specimen surface during the test. In this study, creep and creep-fatigue tests with tensile hold-time were conducted on SUS304 stainless steel, with large grain size producted by a particular heat treatment, by using a high-temperature fatigue machine combined with a scanning electron microscope. Microstrain distribution in the grains on the specimen surface during the test was measured by analyzing the distortion of microgrids. The grid pattern with a pitch of about 10 μm was induced by a diamond stylus on the specimen. As result, it was found that the grain deformed uniformly in a direction of stress axis under creep condition. The deformation progressed with inhomogeneous microstrain distribution under creep-fatigue condition. Initiation of microcrack under creep-fatigue condition was mainly related to strain concentration in the grain near grain boundaries. The microcrack under creep condition propagated after reaching a critical crack opening displacement. The crack opening displacement under creep-fatigue condition was smaller than that under the creep condition.
一般社団法人日本機械学会の論文
1996-07-25

クリープおよびクリープ疲労条件下での微小き裂発生・成長と微視的ひずみ分布の関係

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