Effect of Mn Content on the Microstructure and Corrosion Resistance of Duplex Stainless Steels Fabricated by Wire Arc Additive Manufacturing

Duplex stainless steels (DSSs) fabricated by wire arc additive manufacturing (WAAM) have been attracted significant attention by researchers due to their good mechanical properties and corrosion resistance. In this study, nickel-saving cored wires are developed as filler wire for the DSSs via WAAM process. The effect of Mn content on the microstructure and corrosion resistance of WAAM-ed DSSs is studied in detail. The results indicate multiple kinds of austenite including grain boundary austenite, Widmanstätten austenite and intragranular austenite grains are formed among the ferrite in the deposited metals. The ferrite–austenite phase balance can be obtained in the deposited metals. The impedance polarization indicates that the charge transfer resistance increases, whereas the corrosion current density of the deposited metals decreases with increasing the Mn content. From the corrosion morphology, it is observed that the corrosion pits become shallower and decrease on the deposited metals with increasing the Mn content. The increase of Mn content improves the corrosion resistance of the deposited metals via WAAM process.