Effect of nitrogen content on microstructure and mechanical properties of duplex stainless steels via wire arc additive manufacturing

Purpose For the purpose of saving nickel, this study aims to develop new duplex stainless steel cored wires suitable for wire arc additive manufacturing (WAAM) with the addition of nitrogen. Design/methodology/approach The effect of nitrogen content on the microstructure and mechanical properties of the thin-walled deposits is investigated in detail. Findings The microstructure of thin-walled deposits mainly consists of austenite, ferrite and secondary austenite. With increasing nitrogen content, the austenite in the deposited metals increases. The austenite proportion in the bottom region is more than that in the top region of the deposited metals. The χ phase is randomly distributed at the grain boundaries and within ferrite. The σ phase is mainly precipitated at ferrite and austenite grain boundaries. With increasing nitrogen content, the tensile strength of the deposited metals increases, but the impact toughness of the deposited metals deteriorates. Originality/value This study proposes new duplex stainless steel cored wires for WAAM, which realizes the objective of saving nickel.