Thin-Walled Commercially Pure Titanium Structures: Laser Powder Bed Fusion Process Parameter Optimization

Abstract

Laser powder bed fusion (L-PBF) process parameters can be changeable depending on the part geometry due to thermal conductivity differences. The number of studies on the process parameter development for commercial pure titanium (Cp-Ti) with the L-PBF process is also quite limited in the literature. The aim of this study is to present a comprehensive process development for the production of Cp-Ti bulk and thin structures with the L-PBF technology. In the first phase, the right process parameters, including scan speed, laser power, hatch distance, and layer thickness, were identified with prismatic specimens with thin walls so that the obtained parameters could be used for both bulky sections and thin features such as lattice structures. The process parameters were varied to change the volumetric energy density from 19 to 208 J/mm3 among 80 different parameter sets. Parameter sets having a Volumetric Energy Density (VED) value between 32 J/mm3 and 47 J/mm3 gave almost fully dense Cp-Ti parts while the laser power was set to 200–250 W and the scan speed was used as 1000–1400 mm/s. Finally, Vickers hardness and tensile tests were applied to highly dense Cp-Ti parts. This study involving investigating the effect of process parameters on a wide range demonstrated that L-PBF is a favorable manufacturing technology for Cp-Ti parts with almost full density and good mechanical properties as well as good dimensional accuracy even on thin geometries. Moreover, the results show that combining parameters into a single one, i.e., VED, is not a proper way to optimize the process parameters since increasing laser power or decreasing the scan speed may alter the results, although VED is increased in both manners.