The occurrence of room-temperature creep in cracked 304 stainless steel specimens and its effect on crack growth behavior

With the improvement of measurement accuracy, room-temperature creep has been observed in many metallic materials. In the present paper, a SUS304 stainless steel is selected to investigate room-temperature creep at a crack tip and its influence on subsequent fatigue crack growth. Time-dependent deformation at crack tips under constant stress intensity factor was detected at room temperature. The creep deformation is found to increase with increasing overload ratio and constant stress intensity factor. Loading conditions, such as unloading and/or reloading have a significant influence on the deformation. Compared to single wave overload, room-temperature creep under the same overload ratio produces more retardation on subsequent fatigue crack growth behavior. It is shown that crack closure plays a dominant role in this retardation effect.