Enhancing Residual Stress Mitigation in SLM-Fabricated Ti6Al4V Through Process Parameter Optimization and Remelting Techniques

This study investigates the reduction of residual stresses in Ti6Al4V parts produced via Selective Laser Melting (SLM) by optimizing process parameters and incorporating remelting techniques. The effects of laser power, scanning speed, hatch distance, and remelting cycles were analysed using bridge-shaped samples and deformation angle measurements. The Design of Experiment (DoE) study with Taguchi method was utilized to optimize the number of parameter combinations, effectively reducing the number of required experiments. In addition, a modified Volumetric Energy Density (VED) formula accounting for remelting cycles was proposed to provide deeper insights into energy distribution and stress formation in the printed sample. Results indicate that higher laser power and multiple remelting cycles significantly reduce residual stress, but their effects are less stable, evident from the significant variation among the measured results. Meanwhile, scanning speed and hatch distance had minimal effects on the residual stress. According to the DoE study, the best parameter set for minimal residual stress - in order of laser power, scanning speed, hatch distance, and remelting cycles - is (200 W, 1000 mm/s, 0.05 mm, 5 remelting cycles).