Effects of remelting on the surface morphology, microstructure and mechanical properties of AlSi10Mg alloy fabricated by selective laser melting

Abstract

Selective laser melting (SLM) is an additive manufacturing technology that uses laser and metal powder to directly manufacture metal parts. The process has good mechanical properties and dimensional accuracy and can be put into use with a simple post-treatment. However, spheroidisation and warpage can easily occur in the forming process, resulting in poor surface quality and high porosity, which are the main limiting factors for the direct application of the parts formed using this technology. Laser remelting is an effective solution to solve these problems. In this research, the microstructure and mechanical properties of AlSi10Mg fabricated by laser remelting using two different scanning strategies were studied, and it was found that both the laser remelting methods can effectively improve the surface quality, reduce the surface roughness (2.3 μm, 4.0 μm) and porosity (0.08%, 0.2%), refine the grains size and improve the hardness. The thermal conductivity and reflectivity of the metal solidification layer are high, the spreading property of molten pool worsens and the width and depth of the molten pool decrease.