Evolution of multi pores in Ti6Al4V/AlSi10Mg alloy during laser post-processing

Abstract During metal additive manufacturing, porosity is one of the main quality defects of products. Laser post-processing is an effective method of reducing porosity of the metal surface and sub-surface. Herein, the evolution mechanism of multi pores during this process is studied. Two samples for each alloy, Ti6Al4V and AlSi10Mg, were fabricated by laser powder bed fusion (LPBF), and the upper surface of one sample of each alloy was scanned using a laser beam for comparison. Then, the inner layer morphology and pores distribution of these four samples were measured by micro-computed tomography (micro-CT) technology. It was found that the porosity reduced from 0.7961% to 0.6034% for Ti6Al4V and from 3.7105% to 3.6287% for AlSi10Mg after laser post-processing and the phenomenon of combination of pores was obvious for AlSi10Mg alloy. Next, the laser post-processing mechanisms of Ti6Al4V and AlSi10Mg alloys, including heat transfer, Marangoni flow, mass transfer related to recoil pressure and other phenomena, were numerically simulated, and the evolution of pores was tracked by the level-set method. Moreover, the effects of preheating temperature on porosity reduction were discussed.