COMPARISON OF STRESS-CORROSION CRACKING SUSCEPTIBILITY OF THERMALLY-SENSITIZED AND PROTON-IRRADIATED 304-STAINLESS-STEEL USING ELECTROCHEMICAL NOISE TECHNIQUES

The effects of irradiation on the stress corrosion cracking are examin ed through C-ring stress corrosion tests on thermally-sensitized and s ensitized plus irradiated 304 stainless steels using the electrochemic al noise technique. All of the C-ring specimens were bolt-loaded to 30 MPa root m and subjected to an environment of high purity, oxygen-sat urated water at 288 degrees C. During testing the current signal remai ned unchanged on the thermally-sensitized 304SS, whereas the current s ignal of the irradiated specimen steadily increased. The increased cur rent was attributed to the advancement of intergranular stress corrosi on cracks which was subsequently verified with scanning electron micro scopy. The field emission gun - scanning transmission electron microsc opic measurements and radiation-induced segregation model calculations were also carried out in an attempt to correlate grain boundary compo sition with IASCC resistance, It appears that the pre-existing chromiu m depletion profiles were not significantly altered by proton irradiat ion below 0.1 dpa. The increased IASCC susceptibility was probably due to irradiation hardening. (C) 1998 Elsevier Science B.V. All rights r eserved.