A Summary of 10 Years Research on Grade 91 and Grade 92 Steel

In response to the strong needs for the life assessment of various components in fossil power plants, studies on Grade 91 and Grade 92 steels have been jointly performed by EPRI and CRIEPI for a last decade. These studies have been covering the effects of load variation (creep- fatigue) and stress multiaxiality as well as the behavior under uniaxial creep conditions. Based on abundant test data accumulated in this period and associated analytical evaluation, approaches based on inelastic strain energy have been developed for accurately assessing creep damage and failure lives under various conditions. The essence of these efforts is presented in this paper.