Surface roughness improvement of Ti-6Al-4V alloy overhang structures via process optimization for laser-powder bed fusion

In recent years, additive manufacturing of Ti-6Al-4V alloy components via Laser-Powder Bed Fusion has seen increasing application in the aerospace, military, and medical sectors. However, the high surface roughness of up- and down-skin for overhang structures remains a primary impediment to expanded implementation. This study aims to investigate the effects of the overhang angle and process parameters on the up- and down-skin surface roughness of the overhang structure. In addition, the underlying mechanisms leading to the different roughness of the up- and down-skin of the overhanging structure are comparatively analyzed. Subsequently, a response surface model was generated using the biharmonic spline interpolation (V4) method to optimize the process parameters, aiming to simultaneously improve the roughness of both up- and down-skin. Results demonstrate that the optimized parameters reduced the roughness of up- and down-skin by approximately 50 %.