In this study, a boride cladding layer with Mo₂FeB₂ hard phase was prepared on the GCr15 steel via plasma cladding. The phase composition, microstructure, thermal fatigue resistance, microhardness, and wear resistance of the boride cladding layer were investigated. The results revealed that the hard phases in the boride cladding layer were Mo₂FeB₂ and (Cr,Fe)₂₃(C,B)₆, while the binder phase consisted of α-Fe martensite. When the thermal fatigue times increased, the indentation crack length extended in a quadratic pattern, and the crack propagation rate increased. Crack propagation in the cladding layer occurred via both transgranular and intergranular modes. When the thermal fatigue temperature was below 600 °C, the cladding layer exhibited good thermal stability, and a reliable metallurgical bond was formed between the cladding layer and the GCr15 steel substrate. The microhardness of the cladding layer reached 1022.1 HV_0.5, approximately 2.6 times that of the GCr15 steel. The mass loss of the cladding layer increased with the increase in wear load and wear time. The wear of the cladding layer was mainly three-body abrasion wear, resulting from brittle spalling of the hard phase on the worn surface. This study demonstrates the potential of Mo₂FeB₂-based cladding layers for extending the service life of high-value industrial components.

This study investigates the impact of laser cladding process parameters on the forming quality of single-pass, multi-track Stellite 12 alloy coatings on WC9 steel surfaces. Using a Central Composite Design (CCD), mathematical predictive models for cladding efficiency and cladding angle were developed by varying the input process parameters, including laser power, scanning speed, powder feed rate, and overlap ratio. The interactive effects of process parameters on the selected response variables were analyzed. The results indicate that cladding efficiency is most significantly governed by the powder feed rate, and a higher efficiency can be achieved by concurrently increasing both the laser power and powder feed rate. Regarding the cladding angle, the scanning speed plays a dominant role, where appropriately increasing the scanning speed effectively increases the cladding angle by mitigating local mass accumulation. Afterwards, an optimal combination of process parameters was obtained through multi-objective optimization aimed at maximizing both the cladding efficiency and the cladding angle. Experimental validation using the optimized parameters yielded a coating with satisfactory forming quality, with relative errors between the predicted and experimental values for cladding efficiency and cladding angle being 7.22% and 8.81%, respectively. This work provides valuable theoretical guidance for the prediction and control of cladding efficiency and cladding angle of multi-track laser-clad Stellite 12 coatings on WC9 steel surfaces.