A novel low-cost ultra-strong maraging steel by additive manufacturing

A novel Co/Mo free maraging steel, hardened by nano-sized 8-NiAl precipitates, has been developed for additive manufacturing (AM). The composition was designed to achieve ultra-high strength with low cost, simultaneously maintaining the formability. The steel was successfully fabricated using laser powder bed fuse (L-PBF) additive manufacturing (AM) technology, and the effect of heat-treatment on the microstructure and mechanical properties of fabricated samples was investigated. Due to the refined microstructure and high-density dislocations, the as-built samples displayed in excess of 1400 MPa ultimate tensile strength with about 16% total elongation. This is the highest reported strength to date for any as-built AM materials. Upon direct aging treatment, nanoscale ordered 8-NiAl precipitated in the martensite matrix, resulting in a remarkable combination of mechanical properties, i.e. the strength levels exceeding 2000 MPa and elongation up to-8% at room temperature. This work contributes to the development of advanced ultrahigh-strength steel for AM.