MICROSTRUCTURAL AND MICROCHEMICAL MECHANISMS CONTROLLING INTERGRANULAR STRESS-CORROSION CRACKING IN LIGHT-WATER-REACTOR SYSTEMS

This review paper examines mechanisms controlling IGSCC in selected LWR components. Emphasis is placed on identifying material microstructures and microchemistries which promote susceptibility to premature failure. Two important examples are evaluated in some detail: stainless steel pipe cracking and primary-side SCC of alloy 600 steam generator tubing. In each case, grain boundary segregation and precipitation phenomena in these materials are reviewed and assessed relative to the mechanisms of IGSCC. This paper summarizes materials presented at the 1993 International Summer School on the Fundamentals of Radiation Damage held at the University of Illinois. A more comprehensive overview of SCC mechanisms and LWR examples was provided at the school, but will not be included in this article. Microstructural and microchemical aspects controlling IGSCC described here serve as a lead-in to the following paper focussing on how irradiation influences SCC resistance of reactor core components.