A study on microstructure evolution and wear resistance of laser deposited NbC reinforced H13 coating

ABSTRACT This research examines the microstructural development and wear resistance characteristics of NbC-reinforced H13 composite coatings, produced on 30CrMnSiA steel via laser deposition, with NbC proportions varying from 10% to 40%. Employing a methodology that integrated experimental techniques and computational simulations, we utilized models that incorporated both heat and fluid flow dynamics to analyze the molten pool's behavior, its temperature fluctuations, and the subsequent solidification process.The results show that the amount of NbC in the coatings significantly affects their microstructure and mechanical properties.Specifically, a 20% NbC composition yields the most uniform microstructure. Conversely, a 40% NbC concentration results in particle agglomeration and porosity, a consequence of elevated melt viscosity and diminished Marangoni convection, as indicated by flow field analysis. Furthermore, microhardness consistently increased with more NbC, reaching 764.52 HV 0.1 when the NbC content was 40%. This value is roughly 1.27 times greater than that of the pure H13 material.Wear resistance improves substantially with NbC addition; the 40% NbC coating demonstrates the lowest coefficient of friction (0.6) and an 80.05% reduction in wear volume at room temperature, with the wear mechanism transitioning from adhesive wear to mild abrasive wear. At elevated temperatures (400–500°C), high-NbC coatings retain superior wear resistance owing to the thermal stability of NbC and its ability to inhibit plastic deformation. This study clarifies the microstructural changes and wear behavior of NbC-reinforced H13 coatings. This research provides a theoretical basis for creating high-performance metal matrix composite coatings using laser deposition.