Laser cladding of Inconel 713 LC with Stellite 31 powder: statistical modeling and optimization

In the present study, laser cladding of Inconel 713 LC alloy with Stellite 31 powder was carried out using a 400 W pulsed Nd:YAG laser. Central composite design was employed to study the influence of input variables including pulse width, laser frequency, and laser speed on the output responses such as the clad geometry (clad height and clad width), dilution ratio (DR), and hardness. The results indicate that that the pulse width and laser frequency have a direct influence on the clad width, and DR but a reverse influence on the clad height and hardness. However, the influence of laser speed is the opposite of the influence of pulse width and laser frequency. The results depict that the hardness value decreases when the DR raises. By increasing the DR, the concentration of Co and Cr elements in the coating layer reduces, leading to a drop in the hardness. Simultaneous optimization was employed to optimize the cladding process. The pulse width of 12.19 ms, laser frequency of 20 Hz, and laser speed of 4.85 mm s⁻¹ were found as the optimum parameters. The optimum sample has the hardness value of about 480 ± 5 Hv. This value is significantly higher than the hardness value of the substrate (355 ± 3 Hv). The cobalt solid solution phase and Cr₇C₃, Cr₃C₂, W₂C, and WC_x carbides are observed in the clad zone of the optimum sample. (paper)