Effect of post weld heat treatment (PWHT) on the microstructure, mechanical properties, and corrosion resistance of dissimilar stainless steels

The dissimilar austenitic stainless steel (AISI304L) and ferritic stainless steel (AISI430) have been welded with two types of filler metals (316L and 2594L) by GTAW. Then, the effect of heat treatment on the microstructure, mechanical properties, and corrosion properties of welded joint was investigated. Due to remove chromium carbide created during welding process and homogenize the microstructure, heat treatment was carried out on the whole series of the samples at 860 °C and 960 °C. The microstructural, fracture cross-section and corrosive areas of the samples were investigated by SEM. Tensile, bending and potentiodynamic polarization tests were employed to characterize mechanical and corrosion performance of the samples. The results indicate that the welded joints had good mechanical properties after heat treatment so that the best tensile strength was obtained at 960 °C. Due to reduce grain size, the heat treatment samples show minimum corrosion resistance at 960 °C in comparison to 860 °C.