The effect of strain wave shape on the propagation of strain-controlled low cycle fatigue cracks in Type SUS 304 stainless steel was investigated at 600 and 700°C. It was found that the rate of crack propagation in the cycle-dependent region was successfully correlated with a range of cyclic J-integral, regardless of strain wave shape, frequency and test temperature. It was also shown that the rate of crack propagation gradually increased from a cycle-dependent type to a time-dependent one as frequency decreased and slow-fast strain wave shape became obvious, and that the ratio of the range of creep J-intergral to that of total J-integral was an important factor in such a behavior. Furthermore, the fatigue crack initiation mechanism under strain with slow-fast strain wave shape was studied and it was shown that grain boundary sliding took an important role in it.
