Comparison of microstructure and properties of FeCoNiCrMo0.2 and FeCoNiCrMo0.5 high-entropy alloy coatings on the surface of 4Cr5MoSiV steel by laser cladding

•The microstructure evolution of FeCoNiCrMo0.2 and FeCoNiCrMo0.5 high-entropy alloy cladding layer during laser cladding was studied.•The microstructure and main mechanical properties of laser cladding remanufacturing 4Cr5MoSiV1 steel layer have been significantly optimized and improved.•The research results provide a theoretical basis for the preparation of FeCoNiCrMo high-entropy alloy layer, and offer methodological references for the preparation and performance enhancement of 4Cr5MoSiV1 steel surface coatings. In pursuit of the objective to develop coatings with superior microstructure and properties on the surface of 4Cr5MoSiV steel, we employed optimized laser cladding techniques to fabricate FeCoNiCrMo0.2 and FeCoNiCrMo0.5 coatings. Comprehensive studies on the macroscopic morphology, microstructure, fundamental mechanical properties, and electrochemical corrosion resistance of these coatings were conducted. The experiments employed a laser power of 2.5 kW, a beam diameter of 3 mm, a scanning speed of 5 mm s-1, a gas flow rate of 1.5 L min-1, and a powder feed rate of 30 g min-1. The experimental results reveal that both high-entropy alloy coatings formed dense, defect-free metallurgical bonds without pores or cracks. The average microhardness of the FeCoNiCrMo0.2 coating was 342.2 HV0.2, while that of the FeCoNiCrMo0.5 coating was 381.8 HV0.2, representing an 11.57 % improvement and approximately 1.75 times that of the substrate. The FeCoNiCrMo0.5 coating exhibited superior wear resistance compared to the FeCoNiCrMo0.2 coating, with a 39.7 % reduction in wear loss, and both coatings demonstrated significantly better wear resistance than the 4Cr5MoSiV steel substrate. Electrochemical corrosion tests further confirmed the superior corrosion resistance of the FeCoNiCrMo0.5 coating, which had the lowest corrosion current density and the highest open circuit potential, with a corrosion rate 91.04 % lower than that of the FeCoNiCrMo0.2 coating. The experimental process and mechanistic insights provide a theoretical basis and methodological reference for the preparation of such high-entropy alloy coatings.