Effect of Particle Size Distribution on the Printing Quality and Tensile Properties of Ti-6Al-4V Alloy Produced by LPBF Process

Abstract

The efficiency of the fabrication and the cost of feedstock materials are important constraining factors for a wider application of the laser powder bed fusion (LPBF) process in the industry. Therefore, it is necessary to investigate the feasibility of using different particle size distributions (PSD) combined with higher layer thickness for achieving higher building efficiency and cost-effectiveness. This paper focuses on the effect of PSD (0–53, 15–53, 15–75, and 15–105 μm) on the print quality and mechanical properties of the LPBF-processed Ti-6Al-4V at a layer thickness of 60 μm. The results show that volumetric energy density (VED) range, which allows the coarse powder to reach full density, becomes relatively narrower but is still capable of producing fully dense parts when the parameters are properly adjusted. Among the fully dense specimens, the surface roughness varies slightly with the increase of VED and PSD. In the case of proper parameter selection, specimens made of coarse powder can still achieve low surface roughness. Only slight differences in mechanical performance are found for specimens produced using different PSD powders as they have almost identical microstructures. The issue of the anisotropic mechanical properties of the as-built specimens is resolved after annealing treatment at 800 °C for 2 h. This study provides a guideline for producing high-quality Ti-6Al-4V parts using a higher layer thickness and coarser powders.