Electron Backscattered Diffraction Analysis Across the Welded Interface of Post Weld Heat Treated 2205 Duplex Stainless-Steel and 316L Austenitic Stainless-Steel Dissimilar Weldment

In the present work, the effect of post weld heat treatment (PWHT) on the microstructure and micro-texture evolution in 316L austenitic stainless steel (ASS)/2205 duplex stainless steel dissimilar weldments were studied. Weldments were subjected to PWHT at 950 and 1100 °C for 1 h followed by water quenching. PWHT changed the γ (austenite)/δ (ferrite) ratio, average grain size, and grains boundaries (GBs) fraction in the different zones of the weldments. Grain boundary austenite (γGB), Widmanstatten austenite (γWS), and intragranular austenite (γIG) were observed in the heat affected zone (HAZ) on 2205 side and weld zone (WZ). The HAZ on 2205 side showed significant changes in microstructure after PWHT, whereas HAZ on 316L side did not show any significant changes. PWHT at 950 °C showed lower fraction (35%) of δ-phase, whereas PWHT at 1100 °C had a higher δ-phase fraction (53%) in the HAZ on 2205 side. Kurdjumov–Sachs (KS) orientation relationships (ORs) were observed between γ and δ phases in the as-welded and PHWT specimens. Higher fraction of γ/δ grains in HAZ on 2205 side followed the KS ORs for 1100 °C PWHT than as-welded specimen. γ in the as-welded condition (in 2205 BM) showed strong Brass and S components and weak Copper and Cube components. Texture evolution of δ phase in 2205 BM was the dominant Rotated Cube and weak ND//<111> fiber. PWHT causes change in the texture intensity for both γ and δ phase. A decrease in the microhardness values was observed for the PWHT specimens due to the coarsening of the microstructure.