A comparison between Japanese and French A16 defect assessment procedures for creep-fatigue crack growth

This paper presents the results of a benchmark on creep-fatigue crack growth evaluation for a plate subjected to cyclic bending loads with a 1 h dwell. The simplified creep-fatigue crack growth evaluation methods of JNC in Japan and A16 procedures proposed by CEA in France are presented. The methods, based on the reference stress approach, are compared each other. They are found to differ in the expression used for the reference stress solution used to estimate the creep strain. It is also pointed out that in contrast to the A16 procedures, the JNC method takes heterogeneous creep strain distribution into account for small scale yielding condition. The predictions obtained by the methods are also compared to the experimental data. It is found that the methods exhibit conservatisms which are significantly reduced when integrating the creep curve continuously without initialisation during the experiment [Proceeding of SMiRT 14(G13/2), Creep-Fatigue Crack Growth on CT25 Specimens in 316L(N) stainless steel at 650 deg. C]