Feasibility Study on Ductility Exhaustion Approach for Creep-Fatigue Damage Assessment of FBR 316 Stainless Steel Using Published Data

In order to investigate the applicability of a ductility exhaustion rule to the creep-fatigue life assessment of FBR 316 stainless steel, a feasibility study using the published data was conducted. The assessment method was proposed based on the linear damage summation rule. In the proposed method, fatigue damage was calculated by Minor's rule and creep damage was calculated by a ductility exhaustion rule. The creepfatigue lives in the published data were predicted by the proposed method. The results obtained are as follows: (1) All the data could be predicted within a factor of two on life by the proposed method. (2) The creep-fatigue lives under 10 minute strain hold at 550°C were overestimated, while those under 60 minute strain hold at 550°C and 600°C were estimated adequately. From the above facts, the proposed method seemed to be effective for the prediction of creep-fatigue life in which the creep damage was dominant and also the intergranular cracking was remarkable. (3) The creep damage was simultaneously calculated by the time fraction rule in order to compare with the ductility exhaustion rule. All the data could be also predicted within a factor of two on life by this rule, but it tended to overestimate the life.