Environmentally assisted cracking of alloy X-750 in simulated pwr coolant

In this paper, environmentally assisted cracking (EAC) of different heat treatments of alloy X-750 studied in simulated pressurized water reactor (PWR) primary water from 50 to 340 degrees C. The alloy, with single- (704 degrees C/20 h) and two-stage (885 degrees C/24 h + 704 degrees C/20 h) aging treatments, was increasingly susceptible to EAC with decreasing temperature below ∼250 degrees C. This susceptibility was due to hydrogen embrittlement, as indicated by the sensitivity to the hydrogen content of the water and behavior in hydrogen gas. At higher testing temperatures, a second mechanism, possibly anodic dissolution, was dominant for alloys with either a lower solution heat treatment temperature (980 degrees C/ 1 h) or two-stage aging treatment. This second mechanism was suppressed by a higher temperature solution treatment (-1100 degrees C/1 h) and a single-stage aging treatment, which improved alloy performance