Optimization of process parameters for laser cladding of Ni625 nickel-based alloy on ductile iron QT400-18

In order to improve the quality of Ni625 nickel-based alloy laser cladding on the surface of ductile iron QT400-18, the key process parameters of laser cladding based on response surface methodology (RSM) were optimized. A one-way pre-experiment was conducted using different processing parameters. The results show that the microhardness, dilution rate, and aspect ratio of the coating are closely related to the processing parameters, based on the analysis of the microhardness and corss-sectional morphology of the coating. The optimization window of RSM processing parameters was determined. Experiments were designed based on the Box-Behnken Design (BBD) in RSM, and the Ni625 cladding layers were prepared under different process parameters. The experimental results were analyzed using analysis of variance (ANOVA) and RSM. The effects of process parameters on the morphology and microhardness of the cladding layer were determined, and a regression prediction model was established to identify the optimal process parameters: laser power 1700 W, scanning speed 10 mm/s, and powder feeding rate 19 g/min. The cladding layer was prepared using optimized process parameters, resulting in a cladding layer with a well-developed microstructure, good metallurgical bonding, and no cracking defects.