Analysis of relation between the 3D printer laser beam power and the surface morphology properties in Ti-6Al-4V titanium alloy parts

Additive technologies are increasingly widespread in the aviation industry, medicine and implantology. It is essential that the parts manufactured for these applications meet the highest requirements not only as far as their strength, but also surface quality. Thus, high importance should be attached to performing analysis of the manufactured part's surface morphology to ensure optimised functionality, and to selecting appropriate post-processes so as to arrive at the required external surface structure. The paper aims to establish the influence of technological parameters (chiefly of the laser power) of the selective laser melting (SLM) process on the morphological properties of the manufactured surfaces. The changes of characteristics of the Sa and Sq parameters in the laser power P function are non-linear. However, for some values of laser power P (150, 175 W), the Sa and Sq parameters are considerably higher than that in case of the remaining laser power values. The change of the laser power has a strong influence on the structure of individual surfaces, as evidenced by the fact that the highest values of the Sa and Sq parameters were achieved at different laser powers (175 W for the top surface and 150 W for the side surface). The results are shown in graphic form of 2D and 3D morphology profiles and charts. Based on the analysis of parameters describing surface structure properties, optimum values of laser power during SLM process are established. The study also revealed that surface structure analysis should not be focused solely on basic parameters such as average height (Sa) or root-mean-square height (Sq), but also on parameters such as kurtosis (Sku) and skewness (Ssk), which yield important information on surface stereometry. Precisely established surface stereometry allows assessing properties such as wear resistance, corrosion, tribological properties, and the ability to integrate medical implants with live organism tissue.