Effect of surface roughness on tensile properties of additively manufactured thin-walled structures

Official URL: https://risc01.sabanciuniv.edu/record=b2862129_(Table of contents)

Additive manufacturing (AM) has enabled manufacturing of complex geometries that are infeasible to produce with conventional manufacturing methods. Among the AM methods, laser powder bed fusion (LPBF) has gained significant attention from various industries due to its ability to fabricate components with intricate details. With LPBF processes, it is possible to manufacture functional lightweight components with thin walls and internal features that may not be accessible for secondary surface finishing operations. However, due to the nature of the process, AM produces undesirable surface quality, especially on the down-facing surfaces of inclined walls, which can negatively impact mechanical performance. In this study, thin-walled Cobalt-Chrome (CoCr) test samples were manufactured through LPBF with varying build angles and thicknesses to investigate the influence of surface roughness on tensile properties. The produced surface textures were analysed, and the areal surface roughness metrics were quantified. The effects of process parameters such as wall thickness, build angle, and angle of the laser incidence on the surface roughness were investigated. Tensile tests were conducted on both as-built samples and their machined counterparts, and the results showed that the negative impact of surface roughness becomes less significant as sample thickness increases. Analysis of Variance (ANOVA) was used to identify the most influential surface roughness metrics on tensile properties. According to the ANOVA results, while v Sv, S10z, and Sku were the most influential parameters on ultimate tensile strength, Sa, Sq, Sv, and S10z was found to be significant for effective modulus.