Hold-Time Effects on the Elevated Temperature Fatigue-Crack Propagation of Type 304 Stainless Steel

Fracture mechanics techniques were used to study the effects of loading waveform and holdtime on the fatigue-crack propagation behavior of Type 304 stainless steel at 1000°F. At frequencies of 4 and 0.33 cpm, there was little observable difference between the results using a sawtooth waveform, and those using a square wave with hold-time. At 0.083 cpm, however, the tests with hold times exhibited a somewhat lower rate of crack growth than those using a sawtooth waveform. The reason for this is unknown, but several possible explanations are offered.