Recovery and recrystallisation during creep exposure of cold worked Ti-modified 14Cr–15Ni austenitic stainless steel

Abstract

ABSTRACT Creep behaviour of Ti-modified 14Cr–15Ni austenitic stainless steel in solution annealed, 20%, 30%, and 40% cold-worked conditions, was studied at 973 K and 175 MPa stress level in the current investigation. Increase in cold-work level resulted in denser dislocation network resulting in prominent low-angle grain boundaries. Low-angle boundary fraction increased as the amount of cold working increased from 20% to 40% prior to creep loading. The variation in the fraction of low-angle boundaries impacted the creep rupture strength of the steel. During creep exposure of the cold-worked steels, softening occurred due to both recovery and recrystallisation. The extent to which recrystallisation and recovery occurred during creep was dependent on the level of cold work. Subgrain formation and recrystallisation resulted in enhanced recovery and decreased the creep strength of 40% cold-worked steel. The creep rupture life was highest for 30% cold-worked steel.