Influence of welding thermal cycles on microstructure and pitting corrosion resistance of 2304 duplex stainless steels

Different welding thermal cycles from single-pass to triple-pass were performed on two kinds of 2304 duplex stainless steel through Gleebe thermal–mechanical simulator. The corresponding microstructure was observed, while the pitting corrosion resistance was investigated in 1.0 M NaCl by potentiostatic critical pitting temperature (CPT). The results showed that single-pass welding deteriorated microstructure and pitting corrosion resistance significantly. As the welding pass increased, the ferrite content decreased and CPT increased. However, CPT was still lower than that of the base metal. Nitride precipitated at the boundary between ferrite and austenite phase for low-alloyed 2304 after the single-pass welding thermal cycle.

► Thermal cycle simulation of welding with different pass was performed on DSS. ► Microstructure evolution and pitting corrosion with welding pass were analyzed. ► Single-pass welding deteriorated microstructure and pitting resistance greatly. ► Multi-pass welding modified microstructure and pitting resistance to some extent. ► Adding γ-stabilizing alloying elements was beneficial for welding process.