To explore the influence of different welding modes on the properties of 316L thin-plate welded joints, a new type of laser arc compound gun head similar to a coaxial one was used in this experiment. A high-speed camera was used to record the welding process and analyze the droplet splash behavior of the molten pool. The microstructure, microhardness change, and tensile test results of welded joints under different welding modes were analyzed. The results showed that laser welding (LW) is more prone to molten pool splash than hybrid laser arc welding (HLAW). The HLAW pool area was significantly increased compared with that of LW. The HLAW joint microstructure was more uniform than that of LW, which can improve the microhardness of welded joints. HLAW improved the tensile properties of the joint, with the maximum tensile strength of the joint increasing from 433 to 533 MPa. This test can provide guidance for the HLAW process.

The high cooling rate and temperature gradient caused by the rapid heating and cooling characteristics of laser welding (LW) leads to excessive thermal stress and even cracks in welded joints. In order to solve these problems, a dynamic preheating method that uses hybrid laser arc welding to add an auxiliary heat source (arc) to LW was proposed. The finite element model was deployed to investigate the effect of dynamic preheating on the thermal behavior of LW. The accuracy of the heat transfer model was verified experimentally. Hardness and tensile testing of the welded joint were conducted. The results show that using the appropriate current leads to a significantly reduced cooling rate and temperature gradient, which are conducive to improving the hardness and mechanical properties of welded joints. The yield strength of welded joints with a 20 A current for dynamic preheating is increased from 477.0 to 564.3 MPa compared with that of LW. Therefore, the use of dynamic preheating to reduce the temperature gradient is helpful in reducing thermal stress and improving the tensile properties of the joint. These results can provide new ideas for welding processes.

The aim of this investigation was to examine how CeO₂ powder influences the performance of WC + Ni60 composite powder. Various cladding layers of WC + Ni60, incorporating differing mass fractions of CeO₂, were created on the surface of Q235 steel utilizing laser cladding technology. To analyze the microscopic structure of the resulting cladding layer, scanning electron microscopy was employed. Additionally, the abrasion and corrosion resistance properties were assessed through experimentation with a pin-and-disc friction and wear tester and an electrochemical workstation, respectively. The results of the study showed that when the mass fraction of CeO₂ was 1%, the grain on the surface of the coating was refined, the carbide formation was reduced, and the uniformity of the cladding layer was the best. In terms of corrosion resistance, the coating with 1% CeO₂ had a self-corrosion potential of 0.07 V and a self-corrosion current density of 1.82 × 10⁻⁵ A·cm⁻², showing the best corrosion resistance, and the coating self-corrosion potential was higher than that of the coating and substrate without CeO₂. In terms of abrasion resistance, coatings with 1% CeO₂ had a lower coefficient of friction (0.47) and a smaller wear rate 0.034 mm³, and the wear amount was only 23.5% of that of coatings without CeO₂, resulting in the best wear resistance. In conclusion, coatings containing 1% CeO₂ exhibit the minimal coefficient of friction and the lowest wear rates, while simultaneously providing optimal corrosion resistance.

In order to study the effect of laser remelting on the properties of Q235 steel, WC-enhanced nickel-based remelted layers at different powers were prepared on the surface of Q235 steel using laser cladding technology. Their micro-morphologies were observed using scanning electron microscopy, and their hardness and corrosion resistance were tested using a Vickers hardness tester and an electrochemical workstation. The results show that when the laser power reached 1600 W, the number of WC particles was reduced, the fragments of the broken reinforcement particles were more evenly distributed, the fused layer had the highest uniformity, and the microhardness was more average. Additionally, the corrosion current density reached 2.397 × 10⁻⁵ A/cm², the self-corrosion potential E_corr of the remelted coatings was positive relative to the substrate, the corrosion resistance was the highest, the coating was uniformly flat, and its hardness was the highest.

In this study, Fe/TiC composite coating was fabricated on the surface of 65Mn steel using substrate preheating combined with laser cladding technology. In order to characterize the impact of various preheating temperatures, four coatings were fabricated on a 65Mn substrate using laser cladding at different temperatures (ambient temperature, 100 °C, 200 °C, and 300 °C). The microstructures and properties of four Fe/TiC composite coatings were investigated using SEM, XRD, EDS, a Vickers microhardness meter, a wear tester, and an electrochemical workstation. The research results show that the cladding angle of the Fe/TiC composite coating initially increases and then decreases as the substrate preheating temperature rises. The solidification characteristics of the Fe/TiC composite coating structure are not obviously changed at substrate preheating temperatures ranging from room temperature to 300 °C. However, the elemental distribution within the cladding layer was significantly influenced by the preheating temperature. An increase in the preheating temperature led to a more uniform elemental distribution. Regarding the comprehensive properties, including hardness, wear characteristics, and corrosion resistance, the optimum substrate preheating temperature for the cladding layer was found to be 300 °C.

In this study, laser melting experiments of Ni60/WC composite powder coatings were carried out using a laser, and the surface morphology and microstructure of the coatings were analyzed using a scanning electron microscope (SEM) coupled with energy dispersive X-ray spectroscopy (EDS). In addition, hardness testing equipment was used to assess the hardness of the coatings and an electrochemical workstation was used to characterize their corrosion resistance. The key findings demonstrate substantial variations in coating performance based on remelting parameters. The coatings processed without secondary laser remelting exhibited an average hardness of 501.36 (standard deviation 154.46) HV_0.2, a self-corrosion potential of −0.039 V, and a self-corrosion current density of 8.11 × 10⁻⁴ A/cm². In contrast, some coatings were subjected to secondary remelting at 800 mm/min (S 800). The laser is used to scan the surface of the cladding with the laser on the surface of the cladding, and the speed is the feed rate of the laser scanning. XRD analysis revealed intensified main peaks, indicative of elevated solid solution and carbide content. SEM micrographs displayed fishbone-like and feather-like morphologies, with the hardness increasing to 622.98 (standard deviation 9.60) HV_0.2 and the corrosion metrics improving to −0.038 V and 2.86 × 10⁻⁵ A/cm². In contrast, coatings remelted at 600 mm/min (S600) exhibited broader but less intense XDR peaks, alongside diminished reticulation in SEM imagery. These samples demonstrated marginally lower hardness 599.91 (standard deviation 8.35) HV_0.2 but superior corrosion resistance, with a self-corrosion potential of −0.012 V and current density of 2.64 × 10⁻⁵ A/cm². The results underscore the critical influence of laser scanning velocity and remelting frequency on microstructural evolution, mechanical strength, and electrochemical stability. Enhanced hardness correlates with refined microstructural features, while enhanced corrosion resistance arises from reduced defect density and stabilized electrochemical activity.