Design of a Cobalt-Free Maraging Steel with Ultra-High Strength of 2.3 GPa Through Additive Manufacturing

Additive manufacturing (AM) is a revolutionary technology that enables the production of components with complex geometries and exceptional properties, which has attracted significant research interest. However, one potential challenge associated with additive manufacturing is its increased susceptibility to cracking resulting from the incorporation of high alloying elements. Furthermore, the formation of brittle Laves phases is frequently observed in cobalt-containing maraging steels, which significantly compromises the ductility of these materials following heat treatment. Here, we demonstrate that by minimizing the crack susceptibility of the steel and introducing high-density Ni₃Ti and NiAl nanoprecipitates with a core-shell structure, these challenges are simultaneously addressed. The cobalt-free maraging steel, with a composition of Fe-18.5Ni-4.6Mo-1.5Ti-0.9Al-0.05C-0.01Y, is computationally designed to achieve high crack resistance and martensite start temperature. The alloy exhibits a transition from columnar to equiaxed grains and a uniform elemental distribution after printing. After aging, it achieves exceptional mechanical properties, with a tensile strength of 2.3 GPa and an elongation of 5.7%, making it a more promising alternative to conventional alloys. This study provides a potential avenue toward the design of cost-effective, high-performance, and sustainable alloys for additive manufacturing.