A comparative study on microstructural, mechanical and cryogenic machinability of Ti6Al4V fabricated via SLM and EBM additive manufacturing technologies

Powder bed fusion (PBF) printing technologies have enabled the fabrication of high-performance Ti6Al4V parts for aerospace and dental uses, yet exciting challenges in high-precision printing and enhanced strength properties still exist. Herein, gas atomized spherical metallic powder of Ti6Al4V was selected for selective laser melting (SLM) and electron beam melting (EBM) to analyze and compare their microstructural characteristics and tensile properties. Moreover, the machinability behavior of SLM/EBM Ti6Al4V under cryogenic CO 2 cooling was investigated in perspective of surface quality, milling forces and tool wear at varying milling parameters. The findings have shown minor molten pool pits and non-fusion pores, visible on the top surface of the samples printed by both SLM and EBM. The XRD analysis revealed a dominant α/α' phase, with closely matched experimental and calculated results. The stress-strain curve of SLM samples showed 18% and 9.5% higher Yield Strength (YS) and ultimate tensile strength (UTS) than EBM samples. The milling of EBM Ti6Al4V samples showed relatively higher cutting forces, roughness, and flank wear at all feeds and speeds. Specifically, the machined workpiece roughness in parallel and across the feed direction were twice for EBM samples than SLM printed Ti6Al4V samples. In this holistic analysis of Ti6Al4V aerospace component manufactured through two PBF technologies, SLM produced small grain boundaries, and a fine ⍺-structures provided relatively lower cutting forces due to less shear resistance, while EBM samples with α-dendritic structures, led to higher forces and tool wear. This study shed light on a “process-characterization” link that govern the cutting process and material deformation. A framework will reveal the additive and subtractive manufacturing assessment regarding the critical applications of PBF for aerospace components.