Microstructure Evolution and Wear Mechanism of NbC‐Reinforced 65Cr8MoNb X Coatings Fabricated by Laser Cladding

Incorporating niobium (Nb) into Fe–Cr–C alloys effectively enhances their mechanical properties. This study investigates how Nb content (0–4 wt.%) affects the microstructure and mechanical performance of a laser‐clad 65Cr8MoNb X coating, using the NbC area fraction as a key optimization indicator. The phase evolution was characterized via JMatPro, X‐ray diffraction, scanning electron microscope, and transmission electron microscopy. Experimental results show that as the Nb content increases from 2 to 4 wt.%, the area fraction of NbC precipitates increases correspondingly from (5.95 ± 0.79)% to (27.72 ± 1.35)%, and their size gradually increases. In correspondence, the microhardness of the coating slightly decreases from a peak of 622 HV at 2 wt.% to 604 HV at 3 wt.%, and then sharply drops to 451 HV at 4 wt.%, while the wear rate rises significantly. This indicates that excessive Nb addition impairs the mechanical properties of the coating. Wear mechanism analysis indicates a shift from abrasive wear (without NbC) to adhesive wear (with NbC). This work provides a basis for optimizing iron‐based wear‐resistant coatings.