2024 Volume 73 Issue 5 Pages 123-133
Authors experienced two type damages in the Type-316 stainless steel loading devices which were used for SCC tests in simulated PWR primary water or BWR water. These damages were 1） cracking at the bottom of the commercial rolled thread used in the simulated PWR primary water at 340℃ for 3,000 hours and 2） cracking at the round corner of the cantilever beam type loading device used in the simulated BWR water at 288℃ for 1,000 hours. We observed fracture surfaces of the crackings in the devices and compared them with fracture surfaces in our previous and recent new SCC specimens. The fractographic study revealed that both quasi-cleavage transgranular fracture surface and intergranular surface existed in the device as well the SCC specimens. We therefore postulated that the crackings in the devices were produced by environmental assistance of high temperature water, and not by the mechanical fracture due to materials defects.
