Formation and reduction of hydrogen porosity during selective laser melting of AlSi10Mg

This study shows that the hydrogen porosity in AlSi10Mg parts built up with selective laser melting (SLM) can be lowered by efficient drying of the powder as well as by the modification of the process parameters. Complex structural and functional parts can be made of AlSi10Mg by SLM. Many previous investigations show that SLM with AlSi10Mg leads to high build-up rates and even better mechanical properties than casting does. But, besides all the advantages of manufacturing aluminum parts with SLM, hydrogen porosity as known from other aluminum processing methods leads to a density loss. To investigate the hydrogen porosity in SLM, cube-shaped samples were manufactured using different drying methods of the powder and varying process parameters. Regarding the density measurements, the SLM samples were evaluated to study the influence of the drying methods and process parameters on the porosity. Furthermore, the results were discussed with respect to the physical phenomena of the SLM process. In this context the physical mechanism of the hydrogen pores was investigated.