Evolution of an Alloy 690 Surface During Oxidation in a Simulated Pwscc Environment

Abstract

The anomalous internal oxidation of Alloy 690 in a simulated primary water environment has been studied by time-resolved SEM and EDX studies. The relatively protective external oxide formed near grain boundaries has a fairly constant width from short exposure times, but the grain boundary region is dynamic, with signs of temporary internal oxidation, accompanied by stress relief due to diffusion of nickel to the grain boundary.