Impact of Heat Treatments on the Susceptibility to Localized Corrosion of AISI 316L Stainless Steel

Abstract

This work evaluates the microstructural behavior of an AISI 316L stainless steel subjected to accelerated corrosion testing, considering exposure times to a saline atmosphere of 8h, 50h, and 96h. The samples were previously solution-treated at 1100°C for 1 hour, followed by water quenching and others by air cooling, and then isothermally sensitized at 650°C for 6 hours with slow furnace cooling. Intense attacks were observed on austenitic grain boundaries using optical microscopy, possibly attributed to the precipitation of different phases identified by X-ray Diffraction. As a result of the corrosion tests, a higher degradation rate and mass loss per unit of time was observed in the thermally treated and air-cooled sample compared to its water-cooled counterpart. This was evident when observing the samples using Confocal and Scanning Electron Microscopy (SEM), where a more extensive intergranular degradation and its propagation through areas associated with chromium carbides were determined.