Abstract
A fractographic study was carried out on the creep-fatigue interaction during the crack propagation process of a 304 stainless steel under repeated stress at 650°C. In general, the crack started as a transgranular fatigue crack and changed to an intergranular creep crack at a certain crack length. The transition point moved to the later stage of crack propagation as the period of repeated stress increased. This transition phenomenon could be explained by assuming that both of the crack propagation processes, the transgranular fatigue crack and the intergranular creep crack, are possible under repeated stress condition and that the one with a higher rate actually occurs. The linear fracture mechanics was applicable to explain this phenomenon in spite of the fact that the experiments were conducted under creep condition.
