This review examines the methods used to optimize the process parameters of laser cladding, including traditional optimization algorithms such as single-factor, regression analysis, response surface, and Taguchi, as well as intelligent system optimization algorithms such as neural network models, genetic algorithms, support vector machines, the new non-dominance ranking genetic algorithm II, and particle swarm algorithms. The advantages and disadvantages of various laser cladding process optimization methods are analyzed and summarized. Finally, the development trend of optimization methods in the field of laser cladding is summarized and predicted. It is believed that the result would serve as a foundation for future studies on the preparation of high-quality laser cladding coatings.

As high-end equipment manufacturing advances, demand for improved surface performance in critical components has increased. Laser cladding is an advanced surface strengthening technique that affords effective surface modification. During the laser cladding process, obtaining a fine grain microstructure usually helps to enhance the microhardness, wear resistance, and corrosion resistance of the cladding layer. However, conventional laser cladding often yields coarse columnar grains that limit further performance improvements, so process optimization to achieve grain refinement is necessary. In this study, oscillating laser cladding was combined with a pulsed-wave (PW) laser mode to deposit a fine-grained Al₂CrFe₂Ni₄Ti_1.5 high-entropy alloy cladding on Q550 steel substrates. Compared with continuous-wave (CW) laser cladding, the PW mode produced markedly refined grains and concomitant improvements in microhardness, wear resistance, and corrosion resistance. Specifically, the microhardness of the PW cladding layer reached approximately 673.34 HV_0.5, the wear volume was approximately 0.06 mm³, the wear rate was approximately 0.21 × 10⁻⁴ mm³/N·m, and the corrosion current density decreased to approximately 1.212 × 10⁻⁵ A·cm⁻². This work presents a novel approach for producing high-performance, wear-resistant, and corrosion-resistant high-entropy alloy cladding layers, and offers both theoretical insight and potential engineering applications.

This study utilized oscillating laser cladding technology to fabricate nickel-based composite coatings, systematically investigating the influence of varying laser powers on their morphology, microstructure, and properties. The results indicate that as laser power increases from 800 W to 1400 W, the dilution rate of the coating exhibits a non-monotonic change, reaching a maximum at an intermediate laser power due to the competing effects of enhanced substrate melting and melt-pool instability. The microstructure of the coatings is primarily composed of dendritic and equiaxed crystals. Elemental analysis revealed that Ni is predominantly enriched within the dendritic regions, whereas Cr segregates toward the grain boundary areas. Furthermore, the microhardness of the coating, as well as its anti-wear and anti-corrosion properties, are positively correlated with the laser power. When the power reaches the maximum value of 1400 W studied, the performance of the coating significantly improves. The average hardness is 482 HV, and the relative wear resistance is approximately 1.8 times that of the coating when the power is 800 W. The corrosion current density is 9.04 × 10⁻⁷ A/cm².

This study introduces a novel type of oscillating laser directed energy deposition (OL-DED) technology aimed at improving microstructure uniformity and enhancing wear resistance. The microstructure and wear resistance of the OL-DED coating were analyzed and compared with those of the traditional non-oscillating laser directed energy deposition (TL-DED) coating. The results indicate that the OL-DED coating exhibits superior performance, and the grain size of the OL-DED coating is significantly smaller than that of the TL-DED coating. Furthermore, the wear resistance of the OL-DED coating at room temperature and high temperatures exceeds that of the traditional TL-DED coating. The wear mechanisms at room temperature are primarily characterized by abrasive wear, adhesive wear, and oxidative wear, whereas those at high temperatures are mainly dominated by abrasive wear and oxidative wear, with a slight contribution from adhesive wear.

Laser cladding technology is a widely applied surface modification technique; but its inherent process characteristics render it susceptible to cracking. The addition of rare earth oxides has proven to be an effective approach for curbing crack formation and enhancing the comprehensive performance of the coating. This review summarizes the mechanisms by which rare earth additives improve the coating microstructure, molten bath behavior, and interfacial bonding strength, including adjusting surface tension, purifying the molten bath, and forming interatomic chemical bonding. The addition of rare earth oxides significantly improves the forming quality of materials, which contributes to a finer and more uniform microstructure and directly enhances material hardness and resistance to plastic deformation, thereby altering wear behavior and improving wear resistance. The increased hardness provides better support for the surface oxide film, while the improved microstructure mitigates galvanic corrosion and intergranular corrosion susceptibility, leading to enhanced corrosion resistance. In addition, the article incorporates relevant quantitative analysis to provide a reference basis for the type selection, content optimization, and particle size selection of rare earth additives. This article provides a coherent framework for understanding how the addition of rare earths transfers its effects from the process to the performance. However, the industrial application of rare earth oxide laser cladding faces key bottlenecks such as additive deactivation under extreme conditions, threshold effects, nano-agglomeration, and cost constraints.