EVALUATION OF THE SUSCEPTIBILITY TO PWSCC OF NICKEL-BASE WELD METALS WITH THE SLOW STRAIN RATE TENSILE TESTS ON HUMP-TYPE SPECIMENS

摘要

Slow strain rate tensile (SSRT) on hump-type specimens were conducted on Alloy 82, 52i and 52 and on the developed weld metal, TG-SN690Nb exposed to simulated PWR primary water environment and in an inert environment for evaluating the PWSCC (primary water stress corrosion cracking) susceptibilities of the listed alloys. Alloy 82 is known to exhibit a susceptibility to PWSCC, and the time to failure (fully dendritic) is about 59% of the lifetime in the inert environment. The ratios between the lifetimes in primary water to that in the inert environment is about 80% for Alloy 52 (FM52M) and Alloy 52i without dendrite fracture surface. The developed alloy of TG-SN690Nb has the lifetime ratio of about 97% demonstrating its excellent resistance to PWSCC.