THE CORROSION-ENHANCED PLASTICITY MODEL FOR STRESS-CORROSION CRACKINGIN DUCTILE FCC ALLOYS

Critical experiments are presented to test the corrosion enhanced plas ticity model proposed some years ago by one of the present authors to describe the SCC of austenitic stainless steels in Cl- solutions. Slow strain rate tests on [110] and [100] 316 L alloy single crystals clea rly confirm that the macroscopically brittle fracture is in fact achie ved by microcracking on {111} microfacets in a zig-zag manner. Moreove r the corrosion-deformation interactions on which the model is based a re quantitatively analysed through softening effects observed during c yclic plastic deformation in the corrosive solution. The conditions fo r hydrogen entry into the material are described, which leads to the n otion of critical surface defects for hydrogen effects. New developmen ts of the model are discussed in the case of fee ductile alloys.