CHARACTERIZATION of MICROSTRUCTURE, MECHANICAL PROPERTIES and CORROSION RESISTANCE of WELDED JOINTS of 2205 DUPLEX STAINLESS STEEL

2205 stainless steel pipes were welded by flux-cored arc welding (FCAW) and shielded metal arc welding (SMAW). The microstructures and the ratio of phase of the base metal (BM), heat affected zone (HAZ) and weld metal (WM) were examined by optical microscopy. The mechanical properties in the variable zones were also determined. Corrosion properties were evaluated by cyclic voltarnmetry and polarization tests in 3.5% NaCl solution. The results showed that the weld microstructures were ferrite/austenite duplex structure. The hardness of the filler passes of both two welded joints was lower than that of the root passes for the effect of the welding heat cycle. The toughness of SMAW joint was higher than the FCAW joint due to the high austenite volume fraction. The two welding joints had the similar corrosion mechanism, but the FCAW joint had better pitting resistance than SMAW joint, as it present an adequate ferrite/austenite proportion.