Effects of Loading Mode and Temperature on Stress Corrosion Crack Growth Rates of a Cold-Worked Type 316L Stainless Steel in Oxygenated Pure Water

The stress corrosion cracking (SCC) growth rates of a cold-worked Type 316L (UNS S31603) stainless steel specimen in high-purity water at various temperatures were measured under various loading modes at a relatively low stress intensity factor (K) of 15 MPa·m^0.5. A contoured double cantilever beam (CDCB) specimen was used for measuring the crack growth rates (CGR) under constant K conditions. An alternating current potential drop (ACPD) technique was used to monitor the crack growth kinetics throughout the test. The fracture surface shows typical intergranular SCC characteristics. Steady-state CGR values are used to quantify the effects of the loading mode and the environmental temperature. Different unloading/reloading procedures moderately increase the CGR, depending on the holding time and unloading/reloading periods. The crack growth rate increases with temperature in the temperature range between 200°C and 288°C. However, the observed apparent activation energies were different for different temperature ranges. The results show that multiple processes are involved in the stress corrosion crack growth. The effects due to changing the loading mode occurred quickly, while significant time-dependent crack-growth transition periods were observed after increasing or decreasing the test temperatures.