Effect of laser power on microstructural evolution and wear-corrosion resistance of laser-cladded Fe-based alloy on 40Cr steel surface

Fe-based alloy cladding layers were fabricated on 40Cr steel substrates by laser cladding. The effects of different laser powers (2100, 2200, 2300, and 2400 W) on the phase composition, microstructure, microhardness, wear resistance, and electrochemical corrosion behavior of the cladding layers were systematically investigated. The results showed that all cladding layers exhibited a dual-phase structure mainly composed of α- (Fe, Cr) and a small amount of γ-Fe, while the overall phase constitution remained essentially unchanged with increasing laser power. As the laser power increased, the grain size gradually increased, whereas the porosity and microhardness exhibited a trend of first decreasing and then increasing, and first increasing and then decreasing, respectively. The cladding layer prepared at 2200 W exhibited the lowest porosity (0.347%) and the highest average microhardness (632.39 HV), indicating a relatively dense and homogeneous microstructure. In addition, the 2200 W sample showed the optimal wear resistance, with an average friction coefficient of 0.465 and a specific wear rate of 9.27 × 10−15 m3/(N m). Electrochemical corrosion tests in 3.5 wt. % NaCl solution demonstrated that the cladding layer fabricated at 2200 W possessed the highest corrosion potential (−0.170 V) and the lowest corrosion current density (1.29 × 10−8 A cm−2), indicating the best corrosion resistance. Overall, the cladding layer prepared at 2200 W exhibited the optimal comprehensive performance in terms of wear and corrosion resistance.