Slip Bands and Fatigue Life of a Steel under Repeated Impact Tension

摘要

S -N curves of a mild steel under repeated impact tension with the duration of 0.44- 0.64 ms were obtained by using the home-made setup based on the longitudinal impact principle of a pipe and a bar. In addition to the curves, slip bands in grains were observed on the electropolished surface of specimen to clarify the microscopic conditions. As a result, it was found that the ratio of cycles for the initiation of coarse slip bands in grains to those for fracture is within about 10percent, and that slipped grains increase with increasing cycles of impact stress. In the neighborhood of 70percent of fracture cycles, the initiation of microcracks was observed.