Tuning the microstructure and mechanical properties of AlSi10Mg alloy via in-situ heat-treatments in laser powder bed fusion

Together, advanced technologies and metallic materials rapidly progress in the field of Laser Powder Bed Fusion (PBF-LB) additive manufacturing (AM). Although PBF-LB drastically shortens the design-to-manufacture time, post-processing operations on metal parts, including heat-treatments, are often labour intensive and time-consuming. Therefore, we assess the feasibility of conductingin-situ heat-treatments during PBF-LB of AlSi10Mg parts. A build plate heated at set temperatures up to 500 °C was employed while printing for 10–13 h to tune the material's microstructure. For comparison, a batch of samples was printed at 220 °C and 500 °C with a printing time of 4–6 h, which was subsequently solution heat-treated. The experimental results showed that increasing the printing time from 5 h to 11 h while printing at 220 °C resulted in an in-situ direct aging heat-treatment with an actual increment of hardness and strength. Printing at 300 °C induced a significant Al lattice relaxation and consequent in-situ stress relieving of the as-built parts. Lastly, the study shows that in-situsolution heat-treatment is possible when using build plate temperatures between 450 °C and 500 °C for 11 h, although a reduction in ductility (−36%) occurs, as compared to conventionally solution heat-treated counterparts.