Local approach to stress relaxation cracking in a AISI 316L-type austenitic stainless steel : Tomography damage quantification and FE simulations

Abstract : This study deals with the experimental quantification and the numerical prediction of the intergranular damage which developed during residual stress relaxation in the notch root region of AISI 316L-type CT-like specimens tested at 550, 575 and 600 °C. Here, local damage, consisting of cracked grain boundaries, was quantified from synchrotron X-ray tomography data. The residual strain and stress field evolutions in the damaged regions were predicted by finite element calculations. A continuum damage model formulated in terms of a scalar damage variable was calibrated to reproduce the experimental damage distributions in the specimens. The numerical predictions were found to be consistent with the measured damage distributions. It is also shown that the damage model can provide a useful estimate of the propensity to stress relaxation cracking in highly pre-strained AISI 316L-type steels as a function of temperature and magnitude of the initial maximum principal residual stress.