STUDY ON CREEP-FATIGUE LIFE PREDICTION METHODS BASED ON LONG-TERM CREEP- FATIGUE TESTS FOR AUSTENITIC STAINLESS STEEL

摘要

Low-carbon, medium-nitrogen 316 stainless steel is considered as a main structural material of future fast breeder reactor plants in Japan. A number of long-term creep-fatigue were conducted for several products of this steel and two representative creep-fatigue life prediction methods, i.e., time fraction rule and ductility exhaustion method were applied. Stress relaxation behavior during strain holding was simulated by an addition of a viscous strain term to the conventional creep strain but only the latter was counted in the evaluation of creep damage in the ductility exhaustion method. The ductility exhaustion method showed good accuracy in creep-fatigue life prediction for all materials tested, while the time fraction rule tended to overpredict failure.