Microstructure and Mechanical Performances of Stainless Steel Cladding by Twin-Electrode GTAW

Abstract

Twin-electrode GTAW is a novel welding technology in recent years and attracts lots of attention to researchers. However, stainless steel cladding with twin-electrode GTAW has been scarcely reported. This paper investigates the microstructure and mechanical performances of austenite stainless steel cladding by twin-electrode GTAW, and particularly the heat input is concerned. Experimental results of hardness tests, bending tests, and corrosion resistance tests show that both single GTAW and twin-electrode GTAW produce defect-free weld beads which meet engineering standards. Compared to single GTAW, twin-electrode GTAW improves the welding productivity at a lower heat input because of its higher welding speed and melting rate. Oscillation twin-electrode GTAW cladding also produces fine weld bead formation, but causes excessive heat input due to its very low welding speed and relative large welding currents. During oscillation twin-electrode GTAW, Fe–Cr(–Mo) intermetallic compound (σ phase) tends to precipitate in the weld bead, which leads to undesirable ferrite content results.

Stainless steel cladding is usually applied in petro-chemical pressure vessels manufacturing. The traditional GTAW has low welding efficiency. Therefore twin-electrode GTAW was utilized to clad the stainless steel. Experimental results show excellent weld bead formation by twin electrode GTAW with and without oscillation. The mechanical performance of the obtained weld beads meet engineer requirements. Twin electrode GTAW improves welding efficiency profoundly.