THE DEPENDENCE OF IRRADIATION CREEP IN AUSTENITIC ALLOYS ON DISPLACEMENT RATE AND HELIUM TO DPA RATIO

Before the parametric dependencies of irradiation creep can be confide ntly determined, analysis of creep data requires that the various cree p and non-creep strains be separated, as well as separating the transi ent, steady-state, and swelling-driven components of creep. When such separation is attained, it appears that the steady-state creep complia nce, B-0, is not a function of displacement rate, as has been previous ly assumed. Tt also appears that the formation and growth of helium bu bbles under high helium generation conditions can lead to a significan t enhancement of the irradiation creep coefficient. This is a transien t influence that disappears as void swelling begins to dominate the to tal strain, bur this transient can increase the apparent creep complia nce by 100-200% at relatively low (less than or equal to 20) dpa level s. (C) 1998 Elsevier Science B.V. All rights reserved.