In order to investigate the effects of process parameters on the quality of laser cladding layer, Co-based alloy laser cladding experiments based on orthogonal method was performed on the 304 stainless steel by high power diode laser (HPDL). The results show that the laser scanning speed has the most significant influence on the width, height and depth of laser cladding layer, and the powder feeding rate has the most important influence on the hardness of laser cladding layer. For the sake of getting optimum process parameters and reducing the times of process experiments in practical engineering application, a back propagation (BP) neural network model was established to predict the optimum process parameters. The calculation and predication results show a good agreement with the experimental results. The research results have both significant reference value and guidance meaning in processing parameters of Co-based alloy cladding by a high power diode laser in the application.

The objectives of this study are to optimize the key process parameters of laser cladding remanufacturing parts, improve the sealing quality of the hemispherical valve and prolong and improve its service life and reliability. A high-power fiber-coupled semiconductor laser was used to fabricate a single Co-based alloy cladding layer on the pump valve material ZG45 plate. The key process parameters of laser power, scanning speed and powder feeding rate in the process of laser remanufacturing are taken as optimization variables, and the coating width, coating height, coating depth, aspect ratio and dilution rate are taken as response indexes. Based on the response surface analysis method, the central compound experiment is designed using Design-Expert software. The variance analysis of the experimental results is performed, and the regression prediction model of the process parameters relative to the corresponding index is established. Through analysis of the established perturbation diagram and three-dimensional response surface, it is concluded that the main influence factors of melting width and penetration depth are laser power and positive effect, and the main influence factors of melting height are scanning speed and negative effect. The average error of each regression prediction model is lower than 10%. The above research work has important guiding significance for optimizing the process parameters and improving the cladding quality of cobalt-based alloy on ZG45.

In order to solve the wear repair problem of large steam turbine rotor shaft journal, the material of steam turbine rotor shaft was used as a substrate and the self-made special laser cladding remanufacturing powder as the experimental material, and the experiments were carried out by a laser cladding remanufacturing method based on the laser cladding remanufacturing system with coaxial powder feeder. Focusing on effect of different widths of laser cladding layers on total indicated runout (TIR) of steam turbine rotor, the experiment research and mechanism simulation verification were performed, and the influence mechanism of different factors were analyzed. The total data indicates runout are closely related to probe diameter and laser cladding layer width. The width of cladding layer determines the turbine rotor surface magnetic, eddy current density and magnetic flux density distribution. Due to the interference of matrix magnetic field and eddy current density of the surface, the magnetic flux density suddenly changes in the laser cladding layer edge when the laser cladding layer width is less than 8 mm. The measurement results are too large caused by the comprehensive effect of the substrate and the laser cladding layer. According to the numerical simulation of magnetic flux density distribution of measured metal body surface, the critical value of laser cladding width is 9.82 mm.

To improve the mechanical properties and corrosion resistance of the hydraulic column in the mine, a semiconductor fiber-coupled laser was used to laser-clad iron-based alloy powder on a 27SiMn steel substrate (SUB). The microstructure, mechanical properties, and corrosion resistance of the obtained cladding layer (CL) were studied based on experiments. Results show that equiaxed grains at the top of the CL are fine and tightly arranged. Compared with the SUB, the CL average microhardness is increased by 0.3 times, the average friction coefficient is decreased by 0.12, and the wear amount is significantly reduced. The bonding strength between the CL and the SUB is good, and the tensile strength is increased by 10.82%. Compared with the SUB, the mechanical properties and corrosion resistance of the CL are better. The research has an important guiding significance for the practice of hydraulic column repair and strengthening engineering.

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