The Effect of Temperature on the Preferential Intergranular Oxidation Susceptibility of Alloy 600

Oxidation studies were performed on solution-annealed Alloy 600 in high-temperature steam at 400 A degrees C and in simulated pressurized water reactor primary water at 320 A degrees C under environmental conditions where this alloy is known to be susceptible to intergranular stress corrosion cracking. Advanced analytical transmission electron microscopy characterization and detailed scanning electron microscopy analysis highlighted extensive preferential intergranular oxidation as well as enhanced Cr and O diffusivities associated with this oxidation. These findings, as well as the preferential intergranular oxidation susceptibility and diffusion-induced grain boundary migration, are discussed in terms of their roles as precursors to stress corrosion cracking.