抄録
This study has applied the potential difference method using small four-point probe to the non-destructive evaluation of multiple-site small cracks in the low cycle fatigue of SUS316L at 823K in air. The variation of the potential difference detected by the small probe monotonically increased with the number of load cycles and showed sudden increase in the last stage of fatigue. The laser microscopy determined the morphology of small cracks, revealing the random nature of crack initiation sites and increase in the standard deviation of surface crack length with the progress of fatigue. These results revealed that the present fatigue process can be divided into four stages and that the beginning of the last stage can be detected by the four-point probe.
