抄録
The giga-cycle fatigue properties of high-strength steel are important to maintain and manage the equipment. In the present study, the rotating bending test and the ultrasonic loading test up to 10^8 cycles are carried out using the 800MPa grade high strength steels in order to clarify the giga-cycle fatigue of high-strength steel. One of the several specimens failed due to internal fracture over 10^7 cycles in the ultrasonic loading test. It was clarified the origin of fracture on specimen which failed over 10^7 cycles is inclusions, which has large profile area, by fractography.
