Development of Understanding of The Interaction between Localized deformation and SCC of Austenitic Stainless Steels Exposed to Primary Environment

Abstract : Understanding and quantification of interactions between localized deformation in materials and environmental-assisted cracking (EAC) could play an important role in maintaining the integrity of LWR components. Thus, a detailed understanding of strain localization during plastic deformation and of the underlying mechanisms is of great importance for the manufacturing and design of materials exposed to the environment of the primary circuit of PWRs. Thus, the crystal plasticity law of a 304L austenitic stainless steel has been identified, in order to quantify the effect of a change of strain path on the strain localization and increase the understanding of the contribution of the strain hardening and the strain incompatibilities on the mechanisms of initiation of SCC. Pre-deformation of the specimens used for SCC tests was evaluated using image correlation. Constant elongation rate tests and constant elongation tests were conducted for different levels of pre-deformations (0.07 <  < 0.18). Examinations indicated the severe and deleterious effect of the strain localization due to a change of strain path on intergranular SCC susceptibility. Intergranular cracks initiated systematically in the low-deformed areas, where limited deformation (less than 1%) occurred during the exposure to the environment, and where high stress levels due to strain incompatibilities are expected.