Effects of process parameters used in selective laser melting on structural, mechanical and tribological properties of AlSi7Mg alloy

Additive manufacturing technologies, particularly Selective Laser Melting (SLM), have gained an important place in the production of lightweight, high-performance metal parts with complex geometries. However, the structural, mechanical, and tribological properties of the parts produced by this method are directly affected by process parameters, manufacturing strategies, and post-processing processes. In this study, the effects of both production parameters and post-processing processes on the material properties of AlSi7Mg alloy in the SLM production were comprehensively investigated. In the first stage, the effects of laser power, scanning speed, and side-slip distance on the microstructure, relative density, surface roughness, hardness, and tribological behavior were investigated, and optimal production conditions were determined. 10 different scanning speeds, 5 different laser powers, and hatch distances in the range of 30–90% were used, while the layer thickness was kept constant. Samples produced with the optimum parameters achieved a relative density of approximately 99% and a hardness of 114 ± 3.61 HV0.025. Additionally, the effects of the fabrication angle on performance were evaluated by producing samples in 0°, 45°, and 90° building orientations. In the second stage, the effects of annealing, T6 heat treatments, and electropolishing (EP) treatments on the microstructure and fatigue behavior were investigated. EP treatment significantly increased fatigue strength by reducing surface roughness by approximately tenfold. Heat treatments, on the other hand, caused a coarse-grained and spheroidized morphology in the Si network structure, leading to a decrease in hardness, tensile strength, and fatigue resistance. A significant decrease in fatigue limit was observed after T6 heat treatment, which was determined to be due to the thickening of the Si network. The findings clearly demonstrated the effects of production parameters and post-production treatments on the microstructure, mechanical properties, and fatigue life of the material. This study provides a scientific basis for determining appropriate fabrication and finishing strategies for AlSi7Mg alloys produced by the SLE method, particularly in fatigue-critical applications.