To enhance the strength and hardness of steel used in logistics vehicles, CoCrW alloy samples were fabricated on the surface of steel substrates by laser wire deposition technology, and direct aging treatment was adopted to induce carbide precipitation. The effects of aging treatment on the phase composition, microhardness and tensile properties of the alloy were analyzed through microstructure observation and mechanical property tests. The results show that the as-deposited sample is composed of single γ-Co solid solution, and aging treatment promotes the partial transformation of γ-Co solid solution to ε-Co solid solution. In addition, Cr₂₃C₆ carbides are precipitated inside the CoCrW alloy after aging treatment and are uniformly distributed in the matrix. The second phase strengthening effect derived from carbides significantly improves the microhardness of the as-deposited sample, with an average microhardness of (534±17.6) HV, which is increased by about 0.4 times after aging treatment. The tensile strength and the elongation of the as-deposited sample are about (787 ± 16) MPa and (16.6±0.45)%, respectively, while those of aged sample reach (1 318±10.7) MPa and (11.74±0.33)%, respectively. The tensile strength is elevated by approximately 0.67 times after aging. The enhancement in tensile strength is mainly attributed to the synergistic effect of second-phase precipitation strengthening caused by carbide precipitation, strengthening of the matrix induced by HCP phase transformation and grain refinement strengthening.

laser wire deposition  /  phase composition  /  microhardness  /  tensile strength  /  cobalt-based alloy  /  surface coating