STUDY ON CREEP-FATIGUE FAILURE PREDICTION METHODS FOR TYPE-304 STAINLESS-STEEL

Creep-fatigue failure is one of the principal failure modes to be avoi ded in elevated-temperature components of liquid metal fast breeder re actor (LMFBR) plants. To prevent this failure during the plant life wi th sufficient confidence, accurate and reliable methods should be empl oyed for evaluating creep-fatigue endurance. A number of creep-fatigue tests have been conduced to establish a reliable creep-fatigue design methodology applicable to LMFBR plants in the last two decades but th e conditions of these tests are generally far from those expected in a ctual plants. For the purpose of studying the characteristics of vario us creep-fatigue life prediction methods in conditions closer to actua l plant conditions, the authors initiated creep and creep-fatigue test s for type 304 austenitic stainless steel with a special emphasis on t ests with longer durations than past tests. Interim results are summar ized in this paper. Two representative life prediction methods, linear damage fraction rule and ductility exhaustion method, were then appli ed to these test conditions. It was found that both methods can predic t the failure lives with reasonable accuracy. Some comparisons were ma de regarding the characteristics of these two methods.