The influence of laser parameters on the hardness studies and surface analyses of laser alloyed stellite-6 coatings on AA 1200 alloy: A response surface model approach

The development of uniform microstructures with improved performance has been necessitated by the growing importance of Al-based alloys as materials for engineering applications. However, low hardness values limit the application alloys in industries. This research is aimed at enhancing the surface properties of Al-based stellite-6 coatings via laser alloying technique. A 4.4 kW Rofin Sinar Nd:YAG laser emitting 1.064 µm wavelength was used in this study. The laser power was varied in the range of 3–4 kW and the scanning speed in the range of 1.0–1.2 m/min. The optimum laser parameters gave a good metallurgical bonding obtained between substrate and reinforcement at laser power of 3 kW and scan speed of 1.0 m/min. The intermetallic compound and microstructure results in a significant increase in hardness values; which is about 33-times the hardness of the substrate (24 HV0.1). High residual stresses and crack formation were eliminated through optimisation of laser processing parameters, leading to enhanced quality of the coatings, surface adhesion between substrate and reinforcement materials, microstructural evolution and thus improved hardness property.