Effect of grain size on creep rate in type 316 stainless steel at 873 and 973 K

Abstract

The influence of grain size on creep rate in AISI type 316 stainless steel has been investigated at 873 and 973 K over a wide range of applied stresses. Grain boundaries contribute to strengthening at high stresses (180–260 MN m−2) at 873 K but this strengthening does not correlate with the available models which attempt to incorporate the Hall–Petch strengthening effect into high temperature strain rate equations. The importance of loading strain in determining creep rate has been indicated. The creep rate was generally constant at 973 K but increased at small grain sizes and at lower stresses and this has been attributed to the increased contribution of grain boundary sliding at fine grain sizes. The difference in the grain size effects on creep at the two temperatures is attributed to the difference in the substructures developed during creep.