Microstructure and mechanical properties of low cost co-free high strength steel fabricated by plasma arc-based directed energy deposition

Arc-based directed energy deposition (DED) is characterized by high efficiency and excellent manufacturing flexibility, making it a promising choice for fabricating large structural components. High power density plasma arc-based directed energy deposition (PA-DED) was employed to fabricate high strength steel (HSS) component with a new Co-free welding wire. The microstructure and mechanical properties of the component were investigated in detail. The results showed that the matrix microstructure consisted mainly of martensite and ferrite. Austenite was observed in the bottom and middle samples, and the bottom sample exhibited the highest austenite content. All the samples in different regions exhibited a pronounced {100} (001) cube texture. The vertical samples had worse tensile properties than horizontal samples, which would be contributed to the interlayer bands and preferred orientation. The horizontal-middle samples demonstrated the highest tensile strength (UTS: 1207.8 +/- 14 MPa, EL: 15.91 +/- 1.03%). All deposited samples showed strong plastic deformation characteristics, illustrating that the new Co-free HSS components manufactured by PA-DED might replace conventional high-alloy HSS components for industrial applications.