Mechanical Properties and Corrosion Resistance of Cold Metal Transfer Small-Bore Thin-Walled Tube Butt Welded Joints of UNS S32205 Duplex Stainless Steel

The cold metal transfer (CMT) was used to obtain the UNS S32205 Duplex Stainless Steel (DSS) small-bore thin-walled (SBTW) tubes butt joint to study the mechanical and corrosion properties sensitivity of welded joint in low heat input. With the increase in welding heat input, the Widmanstätten-like austenite (WA) becomes thicker and longer while part of them transform into massive austenite. In addition, the two-phase alloying elements gradually tend to be homogenized. The tensile strength of UNS S32205 DSS butt welded joints are above 840 MPa and progressively decreased with increasing the welding heat input. The microhardness of the heat-affected zone (HAZ) is the highest, followed by the weld zone (WZ) and base metal (BM). Welding heat input has a particular effect on the corrosion resistance of welded joints, and the pitting and electrochemical corrosion resistance are slightly weaker than BM. In the test process range, the corrosion resistance of the welded joint is the best under the 1.81kJ/cm heat input.