Pitting and stress corrosion cracking studies on AISI type 316N stainless steel weldments

Pitting and stress corrosion cracking (SCC) studies on the 316N stainless steel (SS) weldments in as-welded (AW) and thermally aged (solution annealing (SA), 550 °C/4 h and 750 °C/1 h) conditions were carried out in acidic and acidic chloride media. Pitting corrosion and SCC resistance was the highest for SA weldment, which was attributed to homogenization of microstructural and microchemical heterogeneities during solution annealing. SA specimen showed the most stable passive film as compared to AW weldment because of higher amount of delta-ferrite in AW weld metal, which resulted in an increased heterogeneity and inferior SCC resistance in AW. Stability of passive film was found to be adversely affected due to heat treatments (at 550 °C/4 h and 750 °C/1 h) because of the precipitation of carbide and sigma phases.