過大変形を受けたフェライト系ステンレス鋼における最大応力固定条件下での疲労限度線図

In this study, experimental investigations were conducted to create fatigue limit diagrams for NSSC180 ferritic stainless steel, which is used for automobile exhaust system parts, subjected to excess deformation, in order to clarify the relationship between the mean stress and the fatigue limit. The fatigue tests were conducted under a fixed maximum stress, which allowed a fatigue design diagram to be obtained. The results indicated that the fatigue limit curve has a region where the effect of increasing the mean stress on the decrease in the fatigue limit is more moderate than that predicted by a modified Goodman line. Furthermore, it was found that a fatigue design based on static crack initiation is more appropriate than the modified Goodman line for higher values of mean stress.