SUS 304鋼のクリープ疲労相互作用に及ぼすクリープ応力の影響

概要

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The combined creep-fatigue tests, in which the stress-controlled creep loading and the strain-controlled fatigue loading are repeated alternately, were carried out on SUS 304 austenitic steel to investigate the effect of creep stress on the creep-fatigue interaction. The creep period under constant loading was 10 hr in a combined cycle, the total strain range in fatigue loading was 1%, and the numbers of imposed fatigue-cycles (N) were 2 and 20. In the test condition with large creep damage (N=2), the total rupture time depended on creep stress. When large fatigue damage was imposed (N=20), little dependency of creep stress was observed. The fracture mode was intergranular for the test condition of N=2. The voids were observed at the grain boundaries perpendicular to the stress axis, and the cracks of a few grain-facet size were observed in the fractured specimen. The fracture seemed to result from the propagation and linkage of grain-facet cracks. For N=20, the fracture mode was transgranular. The fracture caused by the propagation of surface cracks. The linear damage rule and the strain range partitioning method were used to evaluate the results obtained from the tests. For N=20, the actual life agreed with the life predicted from both method. For N=2, the actual life was shorter than the predicted life with lowering creep stress, that is, with increasing life.
社団法人日本材料学会の論文
1979-05-15