查看文章

Grain boundary microstructures and microchemistries are examined in cold-rolled Alloy 690 (UNS N06690) materials and comparisons are made to intergranular stress corrosion cracking (IGSCC) behavior in pressurized water reactor (PWR) primary water. Chromium carbide precipitation is found to be a key aspect for materials in both the mill-annealed and thermally treated conditions. Cold rolling to high levels of reduction was discovered to produce small IG voids and cracked carbides in alloys with a high density of grain boundary carbides. The degree of permanent grain boundary damage from cold rolling was found to depend directly on the initial IG carbide distribution. For the same degree of cold rolling, alloys with few IG precipitates exhibited much less permanent damage. Although this difference in grain boundary damage appears to correlate with measured SCC growth rates, crack tip examinations …