Laser alloying of Hastelloy X with Metco 204 NS powder: statistical modeling and optimization

Abstract Laser surface alloying is a technique that enhances the durability of turbine components by melting a powder coating onto a substrate using high laser power density. This study investigated the statistical analysis of the laser alloying process of Hastelloy X alloy with Metco 204NS powder using response surface methodology to develop a mathematical model and optimize the geometry of the alloying zone and HAZ. The results of this investigation revealed that the width of the alloying zone is most affected by laser power, whereas scanning speed significantly influences the depth of the alloying zone, as well as the depth and width of the HAZ, and the thermal tension angle. The optimal input variables for achieving optimum alloying zone and HAZ geometry are a scanning speed of 6.20 mm s −1 , a laser power of 289.24 W, and a duty cycle of 94%. The errors between the experiment and model-predicted data fall within a range of 0.37% to 15.67%. The values presented indicate the precision of the predicted models and the optimization process. The point, line, and map EDX analyses reveal the presence of the ZrO 2 phase in the alloying zone and show the diffusion of elements from the substrate to the alloying zone. The microhardness results indicate that the alloying zone exhibits the highest hardness due to the ZrO 2 phase, while the HAZ shows intermediate hardness resulting from Zr diffusion, and the substrate retains the lowest hardness.