A Novel T6 Rapid Heat Treatment for AlSi10Mg Alloy Produced by Laser-Based Powder Bed Fusion: Comparison with T5 and Conventional T6 Heat Treatments

AlSi10Mg is the most widely studied Al alloy used to produce components by laser-based powder bed fusion (LPBF), also known as selective laser melting. Several papers have already investigated the effects of conventional heat treatment on the microstructure and mechanical behavior of the LPBF AlSi10Mg alloy, overlooking, however, the particular microstructure induced by rapid solidification. This paper reports on the effects of a T5 heat treatment and a novel T6 heat treatment on microstructure and mechanical behavior of the LPBF AlSi10Mg alloy, consisting of rapid solution (10 minutes at 510 °C) followed by artificial aging (6 hours at 160 °C). The short solution soaking time reduced the typical porosity growth occurring at the high temperature and led to a homogeneous distribution of fine globular Si particles in the Al matrix. In addition, it limited the diffusion processes, increasing the amount of Mg and Si in solid solution available for precipitation hardening and avoiding the microstructural coarsening. As a result, the strength-ductility balance was improved by increasing both yield strength and elongation to failure, respectively of about 14 and 7 pct compared with the best solution among those reported in the literature for conventional T6 heat treatment of LPBF AlSi10Mg alloy.