Morphology and Wear Resistance of Laser-Clad Fe-Cr-Nb-C Alloy Coatings

Fe-Cr-Nb-C wear-resistant alloy coatings were successfully fabricated on high-carbon forged steel via coaxial powder feeding laser cladding. The evolution of microstructure and wear resistance with varying Nb content was systematically investigated. The results indicate that appropriate NbC addition markedly modifies the distribution of grain and boundary carbides. As Nb content increases from 2.5 wt% to 3.5 wt%, nanoscale rod-like NbC precipitates form uniformly along boundaries, effectively suppressing the formation of brittle Cr23C6 precipitation. Semi-coherent NbC/matrix interfaces and NbC-induced grain refinement reduce adhesive/abrasive wear, thereby improving hardness and wear resistance. At 4.5 wt% Nb, discrete micron-sized NbC particles form within the grains, yielding optimal performance. However, excessive Nb (≥5.5 wt%) causes NbC agglomeration, inducing stress concentrations and large spallation pits that deteriorate wear resistance. This work highlights NbC morphology as a key factor for tailoring coating properties.