Microstructure and transient creep in an austenitic stainless steel

Abstract
The dislocation substructures associated with normal and inverted transient creep in annealed and prestrained type 304 austenitic stainless steel were investigated using transmission electron microscopy. Normal primary creep was accompanied by subgrain formation, a process which was accelerated by pre-straining. A prolonged accelerating creep stage was observed under certain test conditions. The associated microstructures revealed that this type of transient creep was also accompanied by subgrain development and a reduction in the free dislocation density. It is concluded that knowledge of the evolution of the dislocation microstructures during transient creep cannot be used to predict whether creep is accelerating or decelerating.