1127 316ステンレス鋼の疲労寿命を支配する損傷因子(OS11-7 材料の疲労挙動と損傷評価-疲労損傷・寿命予測-)

概要

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To predict fatigue life under variable loading accurately, it is important to understand the damage factors determining fatigue life. In this study, the damage factors of high-cycle fatigue were investigated for Type 316 stainless steel. Fully-reversed axial fatigue tests were performed in ambient air at room temperature. In order to evaluate the applicability of linear damage accumulation rule, 2 step stress tests were performed. It was shown that the linear damage accumulation rule did not always evaluate the fatigue life conservatively. Furthermore, the fatigue limit was decreased in the 2 step stress test In order to evaluate the role of cracking on the fatigue life, the surface layer of specimens was removed after the first step of the 2 step stress tests. The fatigue life was extended by the surface removal, although it was less than the life of the undamaged specimen. It was revealed that the fatigue limit of surface removed specimen decreased due to cyclic softening caused by the cyclic loading in the first step, and that the fatigue life of surface removed specimen was equivalent to that obtained by strain controlled tests. It was concluded that the fatigue life of Type 316 stainless steel should be predicted based on the strain amplitude rather than the stress amplitude even for the high-cycle regime.
2010-10-09