STRESS-CORROSION CRACKING MECHANISMS IN DUCTILE FCC MATERIALS

Recent results on the SCC behaviour of ductile fee materials are revie wed. Critical experiments are presented to test the corrosion enhanced plasticity model proposed some years ago by one of the present author s to describe the SCC of austenitic stainless steels in Cl- solutions. Slow strain rate tests on [110] and [100] 316L alloy single crystals clearly confirm that the macroscopically brittle fracture is in fact a chieved by microcracking on {111} microfacets in zig-zag. Moreover the corrosion deformation interactions on which the model is based are qu antitatively analysed through softening effects observed in cyclic pla stic deformation in the corrosive solution. The conditions for hydroge n entry in the material are described, which leads to the notion of cr itical surface defects for hydrogen effects. New developments of the m odel are then discussed and a numerical simulation of the corrosion de formation interactions is presented.