Critical assessment of the hydrogen uptake during the powder-bed laser 3D-printing of Al-Si grade

Recent years saw an increasing interest for 3D printing technologies, particularly the powder-bed selective laser melting for its versatility and easiness. Furthermore, there is currently a trend towards increasing requirements for the structural integrity and mechanical properties of parts and pieces manufactured by 3D printing. However, laser melting and fast solidification of successive layers of powder brings specific defects that need to be characterised in order to be minimised. Furthermore, the use of powder exhibiting huge levels of specific area, magnifies the interactions and reactivity with the atmosphere, potentially bringing oxidation and hydrogen uptake. The present work considers the hydrogen uptake and release in the case of powder-bed selective laser printing of AlSi10Mg alloy. After processing, thermal desorption analysis (TDA) was conducted in order to quantify the levels of diffusible and trapped hydrogen. On the other hand, the microstructure was characterised owing to scanning electron microscopy and x-ray tomography, with specific attention to the porosities