Low alloy steels have been used as the pressure boundary component materials of LWR coolant systems. So it is important to clarify stress corrosion cracking behavior of the alloys. Slow strain rate tensile (SSRT) tests were carried out on two heats of low alloy steels in a simulated PWR secondary water environment under various combinations of temperatures and dissolved oxygen concentration (DO) concentrations.
The results obtained are as follows; a high sulfur steel had SCC susceptibility at the temperatures => 453 K in 0.1 ppm DO. While, a marginal susceptibility was observed in a low sulfur steel at the temperatures between 453 K, and 493 K in 0.1 ppm DO. Both of the steels were almost immune to SCC in DO < 0.005 ppm except in the high sulfur steel at 453 K. Impurity ions...
Keywords: low alloy steel, SCC, high temperature water, SSRT, dissolved oxygen, sulfur content