The influence of laser power on the microstructure and friction performance of laser-prepared TiC-NbC composite coatings on stainless steel surfaces

In order to enhance the hardness and wear resistance of stainless steel surfaces, a crack-free and pore-free TiCNbC coating was prepared on the surface of 304 stainless steel by varying laser power. The study investigated the influence of changes in laser power on the microstructure, microhardness, and friction performance of the TiCNbC coating at room temperature. Experimental results indicate that during the laser cladding process, reinforcing phases such as (Ti, Nb) C and CrB were formed in situ, positively affecting the microhardness of the coating. With increasing laser power, the quantity and distribution of the reinforcing phase (Ti, Nb) C in the coating increased, while the precipitated intergranular hard phases Cr7C3 and Cr23C6 formed a coarser skeleton, leading to a more pronounced enhancement in coating hardness. Consequently, the coating prepared at the highest laser power (1050 W) exhibited the highest average microhardness, measuring at 347.06 HV0.5. The average friction coefficient of the coatings in the experiment was inversely correlated with the wear rate. The coating produced at 650 W exhibited the lowest friction coefficient (0.124) at room temperature; while the coating at 850 W showed the lowest wear rate (0.01591 %). The predominant wear mechanisms for the three coatings at room temperature were abrasive wear and oxidative wear.