Effect of Laser Power on the Microstructure and Properties of a High Speed Laser Clad Fe-based WC Ceramic Composite Coating

To improve the hardness and wear properties of 17-4PH martensitic stainless steel, used commonly to produce steam turbine blades, high speed laser cladding (HSLC) technology prepared the Fe-based WC ceramic composite coating on its surface. The relationship between laser power, microstructure and mechanical properties was judged by analysing the laser clad coating surface flatness, powder utilization rate, hardness and wear performance under different laser powers. The results showed that when the laser power was 2100 W, the scanning speed was 16 mm/s, the powder feed rate was 21.7 g/min and the overlap rate was 40%, the laser clad coating section was in a horizontal state and there were no unmelted powder particles. The powder utilization rate reaches the highest and the hardness reaches the maximum value of 433.02 HV0.5, about 1.27 times that of the 17-4PH stainless steel substrate. In addition, the wear performance is also the best. The observed improvements in hardness and wear resistance are due to the formation of hard strengthening phases such as WC and W2C, as well as the combined effect of fine grain strengthening and solid solution strengthening produced by M7C3 (M=Fe, Cr, W) carbides.