Effects of surface roughness and build thickness on the tensile properties of thin-walled structures manufactured through LPBF

Purpose This study aims to examine how surface roughness arising from laser powder bed fusion (LPBF) impacts the tensile properties of thin-wall cobalt-chrome (CoCr) components relevant to aviation heat exchangers. It aims to quantify the effects of key LPBF parameters and surface texture metrics on the effective elastic modulus, yield strength, and ultimate tensile strength (UTS). Design/methodology/approach Thin-wall CoCr specimens were additively manufactured via LPBF with varied wall thicknesses (0.889, 1.397, and 1.905 mm), build angles (50°, 60°, and 70°) and laser incidence angles. Surface topography was measured using an optical profilometer, and standard areal roughness parameters were extracted. Tensile testing was performed on as-built and machined samples to assess the influence of surface condition on mechanical response. Analysis of variance (ANOVA) was used to identify the most influential roughness metrics affecting tensile properties. Findings As-built 0.889-mm-thick specimens showed the greatest performance degradation relative to their machined counterparts, with average reductions of 12% in effective elastic modulus, 14% in yield strength, and 15% in UTS. Statistical analysis indicated that Sv, S10z, and Sku were most significant parameters influencing UTS, while Sa, Sq, Sv and S10z most strongly affected the effective elastic modulus. Originality/value The paper provides a quantitative linkage between LPBF process-induced surface texture and tensile performance in thin-wall CoCr components, isolating the most influential areal roughness metrics via ANOVA. These results offer practical guidance for parameter selection and post-processing to improve the mechanical reliability of LPBF-fabricated heat exchanger structures in aerospace applications.