Pitting corrosion resistance of micro-zones in welded joint of 2205 duplex stainless steel

The microstructures of welded joint of 2205 duplex stainless steel were studied by optical microscope. Cyclic voltammetry curves of base material,weld metal and HAZ were measured by a self-designed micro electrochemical system respectively. The results show that the microstructures of welded joint of 2205 duplex stainless steel are ferrite and austenite. The percentage of ferrite in weld metal is about 48%,which is equivalent with that in base material,while the average ferrite content in HAZ is more than a half. In the 3.5% NaCl solution,the weld metal shows the consistent pitting corrosion resistance with the base material,but its repassivation behavior is not as good as the base material. Among the three micro-zones of the welded joint,HAZ shows the poorest pitting corrosion resistance and repassivation behavior. The differences on pitting corrosion resistance of different micro-zones of welded joint are relevant to the phase ratio and the distribution of alloy elements in phases.