Effect of Laser Power on Structure and Wear Resistance of Cu-Fe Composite Monotectic Alloy Cladding Layer on 42CrMo Steel Surface

Cu-Fe composite monotectic alloy cladding layers were prepared on surface of 42CrMo steel by laser cladding tin bronze powder at different laser powers (1 000, 1 200, 1 400, 1 600, 1 800 W). The effects of laser power on the microstructure, hardness and friction and wear properties of the cladding layers were studied. The results show that under different laser powers, the cladding layer and the 42CrMo steel substrate had good metallurgical bonding. The structure of the cladding layer was composed of the mixture of Fe and Cu phases. With the increase of laser power, the content of Fe phase in the cladding layer increased, while that of Cu phase decreased. The microstructure changed from mainly consisting Cu-rich phase and mixing with "dispersed spherical" Fe-rich phase to mainly consisting of Fe-rich phase and mixing with "plate-like" Cu-rich phase. With the increase of laser power, the microhardness and the friction coefficient of the cladding layer increased. The main wear mechanism changed from abrasive wear to adhesive wear. When the laser power was 1 200 W, the hardness of the cladding layer was moderate,the friction coefficient was significantly lower than that of the substrate, the wear mass loss was the smallest, the wear surface was flat, the element distribution was uniform,and no significant local oxidation was observed; the comprehensive friction and wear property was the best.