Ultra high cycle fatigue behavior of notched specimen of low alloy steel

摘要

As machine material is used for a long term, the establishment of the fatigue strength evaluation method in ultra high cycle region is needed. In this research then, with the low alloy steel of 1000 MPa level of tensile strength (SCM440 and SCM435), fatigue behavior of a ultra high cycle region in smooth and notched specimens was examined by ultrasonic fatigue test and rotating bending test. As a result, it is thought that the crack thought to stop 10{sup}7 times actually progresses slowly and it became breaking in ultra high cycle region.