The influence of external wire on microstructure evolution and mechanical properties of Co-free maraging steel produced by double-wire double-arc directed energy deposition

Abstract

A Co-free maraging steel wall was successfully fabricated using the double-wire double-arc directed energy deposition (DED) method with an external wire, achieving a high deposition rate of 8.5 kg/h. The thermal behavior during the deposition process, as well as the effect of the external wire on the microstructural evolution and mechanical properties of the fabricated components, were investigated. The external wire reduced the peak temperature and increased the cooling rate of the deposited component. The microstructure predominantly consisted of martensite, with a small amount of austenite. The external wire increased the martensitic content in the area between the two arcs, while reducing the texture intensity in this area. No significant changes were observed in the area directly beneath the arc. The external wire improved the ultimate tensile strength and microhardness of the deposited component. At a feeding speed of 4 m/min, the deposition rate increased by 33 % compared to the conventional double-wire double-arc DED method. The average tensile strength of the samples reached 1233 MPa, with an elongation of 12.4 %. These findings provide new insights into achieving high deposition rates and enhanced mechanical properties in wire-arc DED processes.