Comparison of the stress corrosion cracking growth behavior of cold worked Alloy 690 in subcritical and supercritical water

The stress corrosion cracking growth behavior of cold worked Alloy 690 has been studied in high temperature pressurized water at temperatures between 360 °C and 550 °C. Creep induced cracking was measured at each testing temperature in inert argon environment. Experimental results showed that creep contributed to more than 80% of the overall crack growth rate at temperatures above 450 °C, while only 8% at 360 °C. Sensitization of the post-tested specimens was quantitatively identified, which increased with the testing temperature. The increased degree of sensitization may also contribute to a portion in the overall crack growth rate. It was clearly proved that the dominant mode of cracking from subcritical to supercritical temperatures are different for cold worked Alloy 690. Corrosion induced cracking controls the crack growth rate in subcritical water environment, while creep is the major factor that dominates the cracking in supercritical water.