Understanding the effect of cobalt on the precipitation hardening behavior of the maraging stainless steel

The effect of cobalt on the precipitation hardening behavior of the maraging stainless steels was studied. The hardness test indicated that cobalt addition could advance peak aging time and generate a higher peak hardness. The statistical results of nano-size precipitates distribution demonstrated that cobalt increased the density of precipitates, thus resulting in a stronger precipitation hardening contribution. Based on the first-principles calculations and atom probe tomography (APT) results, a possible mechanism has been proposed to reveal the underlying mechanism: cobalt promotes the nucleation of precipitates by decreasing the diffusion activation energy of Ni and Ti.