Laser cladding Co–Cr–W–C alloy coatings on 5CrNiMo die steel to achieve excellent high-temperature wear resistance

To enhance the wear resistance of 5CrNiMo steel under severe high-temperature service conditions, a Co–Cr–W–C cobalt-based alloy coating was fabricated on its surface by laser cladding (LC). A crack-free coating with metallurgical bonding to the substrate was obtained at a laser power of 1600 W and a scanning speed of 0.01 m s −1 . The coating exhibits a mixed columnar/cellular dendritic microstructure consisting of a FCC matrix and interdendritic Cr- and W-rich carbides. At room temperature (RT), the coating shows a wear rate of 4.95 × 10 −6 mm 3 N −1 m −1 , ∼41% lower than that of the substrate (8.33 × 10 −6 mm 3 N −1 m −1 ). At 800 °C, the coating maintains good thermal stability and a low wear rate of 19.94 × 10 −6 mm 3 N −1 m −1 , corresponding to a ∼97% reduction relative to the substrate (748.75 × 10 −6 mm 3 N −1 m −1 ). The improved wear resistance at both RT and 800 °C is attributed to precipitation strengthening by thermally stable carbides and the formation of a continuous, protective Co- and Cr-rich oxide film that can rapidly re-form during sliding. Overall, this work provides a practical reference for enhancing high-temperature wear performance of hot-work die steels.