Effects of rolling path-induced microstructure and dissolved oxygen on stress corrosion cracking of AISI 316 L stainless steel in high-temperature PWR primary water

The effects of dissolved oxygen (DO) in simulated pressurized water reactor (PWR) primary water on the stress corrosion cracking (SCC) crack growth rates (CGRs) of 16% one-direction cold-rolled (1DCR16) and two-direction cold-rolled (2DCR16) AISI 316 L stainless steel were examined. 1DCR16 material exhibits higher hardness, yield strength and more localized distribution of Kernel Average Misorientation (KAM) values and dislocation density at grain boundaries, with a lower fraction of Σ3 grain boundaries compared to those of 2DCR16 material. In deaerated PWR primary water (<10 ppb DO) at 325°C, 1DCR16 specimens show extensive intergranular SCC (IGSCC), while 2DCR16 specimens exhibit more localized IGSCC, with the average CGR of 1DCR16 being higher. At 290°C in deaerated PWR primary water, 1DCR16 specimens display multiple IGSCC cracks, while only one is observed in 2DCR16 specimens. In oxygenated PWR primary water (DO = 30 ppb, 50 ppb, and 100 ppb) at 290°C, both 1DCR16 and 2DCR16 specimens show extensive IGSCC with similar CGR at each DO concentration and the DO level dominates over microstructural differences. At 290°C and 325°C in deaerated PWR primary water, 1DCR16 specimens have a higher SCC engagement factor than 2DCR16 specimens. However, in oxygenated conditions, the difference in SCC engagement factor between 1DCR16 and 2DCR16 specimens is reduced due to the dominant influence of the high electrochemical corrosion potential in the oxygen-containing PWR primary water.