304ステンレス鋼の高温クリープ疲労における微小き裂の伝ぱ

概要

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The accurate prediction of the fatigue fracture at elevated temperature will depend on the elucidation of the small crack initiation and propagation laws. In this study, smooth specimens of a 304 stainless steel were subjected to the slow-fast cyclic strain of 1% range at 650℃ in air and in a vacuum (about 10^<-2> Pa), respectively. All small cracks on the fixed surface of a specimen were observed with an optical microscope, and their propagation curves and propagation rate were mesured in detail. The surface length and the depth of small cracks covered a wide range, from 10μm to 1 mm. The propagation behavior was classified into two types : propagating cracks with coalescence ; and non-propagating cracks blocked by grain boundary triple points. On the other hand, the statistical treatment of the crack propagation rates showed that the mode of the distribution of their rates agreed with the through macro-crack propagation law, but that their upper and lower limits largely deviated beyond the bounds of the factor of two on the macro-crack propagation rate.
一般社団法人日本機械学会の論文
1986-08-25