Optimization of selective laser melting process parameters for surface quality performance of the fabricated Ti6Al4V

The purpose of this study is to study the influence of the laser power and the scanning speed on the surface hardness, and top surface and side surface roughness of Ti6Al4V metal specimens fabricated via the selective laser melting (SLM) technique. The laser power was varied between 150 and 300 W while the scan speed was varied between 800 and 1400 mm/s. Response surface methodology (RSM) in the Design Expert 11 software environment was used for the design of experiment and results analysis. The distance for surface indentations were targeted at 10–20 μm for the top surface and 60–80 μm for the side surface while the surface hardness profiling was studied using an indenter with the indentation performed at a load of 500 gf and at a dwelling time of 15 s. The study revealed that as the laser power was increased, the surface hardness increases, while the top surface and side surface roughness reduces. Then, when the scanning speed increased, the surface hardness, and top surface and side surface roughness were found to also increase. The optimum range of the process parameters selected are laser speed 300 W and scan speed 1400 mm/s. This produces a minimum surface roughness of 13.006 μm for the top surface roughness and 62.166 μm for the side surface roughness with a corresponding hardness value of 409.391 HV. The findings of this study will assist manufacturers in the process design of the SLM of titanium alloy for aerospace applications.