Evaluation of Low Cycle Fatigue Crack Initiation of Stainless Steel using Reflected Surface Wave from Grain Boundary by High frequency Ultrasonic Wave

摘要

The objective of present study is to develop a method of evaluating the low cycle fatigue crack initiation of stainless steels SUS304 using ultrasonic back scattered wave. A change in back reflection intensity from the surface of the material under cyclic loading was measured. Back reflection intensity decreased before the fatigue crack initiation as the number of cycle increased. Attenuation is caused by the movement of dislocation and this mechanism was considered.