Problematic of heat treatment and its influence on mechanical properties of selectively laser melted AlSi10Mg alloy

Although 3D printing of metals brings a lot of advantages, questions about post-processing techniques arise. In the case of the AlSi10Mg alloy, it is necessary to ensure the best combination of properties, as it is often used in the aerospace industry. Due to the nature of 3D printing, various residues can be found on the surface of the materials and also in the microstructure. Specific post-processing can alter the surface topography and heat treatment can affect the microstructure. The heat treatment can either fully or partially dissolve the printed microstructure, and thus significantly change the properties. The choice of suitable parameters is crucial, since incorrect treatment can result in the degradation of all properties of the material. In this article, the influence of different heat and surface treatments on properties of 3D-printed AlSi10Mg alloy, manufactured by a method of selective laser melting (SLM), was analyzed. Changes in the microstructure, hardness, phase composition, frictional, and strength properties of the given alloy were observed. The results show that the post-process treatment can distinctly change the behavior of the 3D-printed AlSi10Mg alloy. It was found that surface treatment may have a more significant impact on mechanical properties than porosity. Regarding the heat treatment, it was observed that if the residual printed microstructure is not fully dissolved, the yield and tensile strength are slightly increased, while plasticity is drastically reduced. Furthermore, even the partial presence of a printed microstructure leads to a higher volume loss during frictional stress.