Multi-objective Optimization of Hardness and Tensile Strength in Selective Laser Melting-Fabricated AlSi10Mg Using Differential Evolution

Abstract

Abstract Selective laser melting (SLM) of AlSi10Mg has a lot of potential for fabricating lightweight, high-strength components but the concurrent optimization of Vickers hardness (HV) and ultimate tensile strength (UTS) is still not an easy thing to achieve due to intricate process-property interdependencies. This gap is filled in by the present study that involves a Taguchi L9 orthogonal design coupled with a differential evolution (DE) algorithm to find the optimal combinations of laser power and scan speed that are the key decision variables. To be able to balance between HV and UTS, a composite objective function was developed to consider a multi-objective optimization framework. It was found in experiments that there was an interesting trade-off in which, as laser powers increased, UTS increased through better metallurgical bonding, but the surface hardness decreased with coarsening caused by eutectic Si. On the other hand, the finer microstructures and increased HV were facilitated by the lower powers at the cost of tensile strength. The rapid convergence of DE occurred in six generations in which the optimal set was determined as 337.49 W and 1200 mm/s that gives 144.99 HV and 469.85 MPa UTS. These results were supported by microstructural and fractographic studies, which showed a change in a ductile to a quasi-brittle failure mode with change in energy input. This integrative method not only improves mechanical performance but also offers a practical route for tailoring SLM parameters for aerospace and automotive components where mechanical accuracy is of utmost importance.