Atmospheric Pitting Corrosion of TIG Welded Type 316L Austenitic Stainless Steel Under MgCl2 droplets

A pitting corrosion study of Tungsten Inert Gas (TIG) welded Type 316L austenitic stainless steels has been addressed. The results were correlated to the microstructural features of the alloy. The microstructure examination showed that samples consisted mainly of ferrite and austenite microstructure. The vibrating sample magnetometer (VSM) detected the presence of a higher content of ferrite in the weld metal (WM) than in the base metal (BM). The applied solution annealing treatment reduced the ferrite content for both the WM and BM. The solution annealing treatment also changed the morphology of the atmospheric pits. The microhardness measurements varied quite significantly across different regions of the material. The highest values, ranging from 190 to 220 HV, were found in the heat-affected zone (HAZ), while the BM exhibited the lowest hardness. In the weld metal, the hardness values were between 170 HV and 190 HV. Notably, the hardness levels were considerably influenced by the solution annealing treatment, which resulted in a more pronounced decrease, particularly in both the HAZ and weld metal.