A comparative study on heat treatment of martensitic stainless steel prepared by double-wire arc additive manufacturing

This study utilised duplex stainless steel and low-alloy steel wires to prepare martensitic stainless steel (MSS) via heterogeneous double-wire arc additive manufacturing (D-WAAM). The effects of solution + tempering heat treatment on the microstructure, mechanical properties and corrosion resistance of the in situ prepared MSS were investigated. The deposited wall consisted of martensite, δ-ferrite and austenite. After heat treatment, the microstructure transformed into tempered martensite and austenite. Furthermore, heat treatment resulted in refinement of the martensitic lath and increase in the austenite content. Although the micro hardness and tensile strength decreased after heat treatment, the elongation and corrosion resistance were improved. This work provides practical value for in situ preparation of MSS via D-WAAM as well as optimising properties through heat treatment.