Quantifying intergranular corrosion susceptibility in AA2098‐T351 weldments through friction stir welding

Abstract

In this study, the intergranular corrosion (IGC) susceptibility of AA2098-T351 welds, fabricated through friction stir welding (FSW), was systematically evaluated. The evaluation employed American Society for Testing and Materials (ASTM) G110-92 practice and electrochemical impedance measurements, with comparative analyses against unwelded alloys (BS). The key findings depicted that FSW-induced microstructure changes significantly influenced IGC susceptibility across different zones. Zones affected by FSW presented distinct susceptibilities compared with the base metal (BM). The ASTM G110-92 test effectively differentiated the heat-affected zone (HAZ) into segments with changing corrosion resistances based on welding temperature gradients. Cross-sectional analyses using scanning electron microscopy (SEM) techniques correlated corrosion characteristics with microstructural features identified by transmission electron microscopy (TEM). Overall, FSW-induced microstructural alterations emerged as a predominant factor influencing the varying susceptibilities of different zones to IGC, and electrochemical impedance measurements (EIS) validated the findings from ASTM G110-92 practice.