The Influence of Grain Structure on Mechanical Properties of LPBF AlSi10Mg Alloy Obtained via Conventional and KOBO Extrusion Process

This study compares the microstructures and mechanical properties of the AlSi10Mg alloy processed by laser powder bed fusion (LPBF) after undergoing different post-processing techniques. These techniques include conventional extrusion at 350 °C (CE-350) and KOBO extrusion at both room temperature (KOBO-RT) and 350 °C (KOBO-350). The extrusion processes, regardless of the method used, effectively densified the alloy, fragmented the primary silicon network, and refined the grain structure. Notably, a microstructure analysis indicated that the CE-350 method produced the finest grains, whereas the KOBO-350 method resulted in the largest grains. From a mechanical perspective, extrusion significantly increased ductility—rising from 2.4% to more than 14% elongation—while decreasing strength compared to the as-built state. Among the extruded samples, CE-350 provided the best balance of strength and ductility, exhibiting a yield strength of 186 MPa and a ductility of 18.1% elongation. Overall, the results demonstrate that while extrusion enhances ductility, it does so at the expense of strength, with conventional extrusion yielding a more favorable property balance for this alloy under the tested conditions.