Mode II creep crack initiation in 316 LN stainless steel: experiments and modelling

This study deals with the understanding of creep crack initiation and creep crack growth in 316 LN austenitic stainless steel. To evaluate the respective role of the creep strain and that of the main principal stress on intergranular creep damage, original creep experiments were performed on sharp notched thin wall tubular specimens in 316 LN steel tested in torsion at 600°C. The specimens contained a sharply notch perpendicular to their axis. This resulted in overall Mode II loading. In the first part of the paper, the results of four experiments are reported, then, in the second part, a damage model identified previously and based on quantitative observations of grain boundary damage is used to simulate creep crack initiation and creep crack growth. Good agreement between the experimental results and the numerical simulations is found.