Performance optimization and compatibility of FeCoNiCrMo_0.2 high-entropy alloy coatings laser-cladded onto 4Cr5MoSiV1 steel surfaces

4Cr5MoSiV1 steel, known for its excellent toughness, thermal stability, and high hardenability, finds widespread application in areas such as hot extrusion dies, forging molds, and die-casting molds. However, its operational performance and service life are significantly impacted by limitations in surface hardness, wear resistance, and corrosion resistance. This study focuses on the optimization of laser cladding processes, preparing a FeCoNiCrMo 0.2 high-entropy alloy cladding layer on the surface of 4Cr5MoSiV1 steel through laser cladding, and conducts an examination and validation of the microstructure and mechanical properties of the cladding layer. The experiments employed a laser power of 2.5 kW, a beam diameter of 3mm, a scanning speed of 5 mms −1 , a gas flow rate of 1.5 Lmin −1 , and a powder feed rate of 30g min −1 . The results reveal that the top of the cladding layer is dominated by fine and dense equiaxed crystals, the middle by dendritic crystals with secondary dendrite arms, and the bottom by cellular crystals. The cladding layer is primarily composed of a face-centered cubic (FCC) phase structure, with the precipitation of particulate hard σ phases within and between the crystals. The average microhardness of the cladding layer is 360 HV 0.2 , approximately 63.6% higher than that of the base material. The average coefficient of friction for the cladding layer is 0.6609, with a wear volume of about 27 mg, representing an improvement of approximately 18% over the base material; the wear volume is about 81% of that of the base material. In a 3.5% NaCl solution, the self-corrosion current density of the cladding layer is measured at 9.98 × 10 −9 A/cm 2 , with a self-corrosion potential of −368.3 mV. Compared to the base material, it achieves an enhancement in electrochemical corrosion capability while maintaining relative compatibility. The process and research provide a theoretical foundation and methodological reference for the surface modification of 4Cr5MoSiV1 steel.