Microstructure and corrosion resistance of stainless steel produced by bypass coupling twin-wire indirect arc additive manufacturing

This study investigates the application of bypass coupling twin-wire indirect arc welding (BC-TWIAW) in arc additive manufacturing of 18-8 stainless steel. It is found that the droplet transfer changed from short circuit mode to stable spray mode with the welding current rising. Droplet transfer was the most stable when welding current was 200 A. Compared with the conventional MIG welding arc additive manufacturing, the efficiency of BC-TWIAW additive manufacturing can be increased by more than 30%. Electrochemical tests show that the BC-TWIAW overlay has a lower reactivation rate, higher charge transfer resistance, and lower carrier concentration, indicating that the overlay has better resistance to intergranular corrosion and pitting corrosion.