Mechanical Behavior of Additive Manufactured and Powder Metallurgy Ti6Al4V

Abstract

Mechanical behavior of dual-phase Ti6Al4V produced with Direct Metal Laser Sintering (DMLS) was compared to that of similar alloys produced with conventional methods (wrought and machined) and near-net-shape powder metallurgy. The elastic moduli were measured in flexure, stress-strain characteristics were measured in tensile deformation, and fatigue strengths were measured in fully reversed bending. The effect of DMLS fabrication orientation and post-processing by hot-isostatic pressure (HIP) upon mechanical behavior was studied. Both vertically and horizontally-grown DMLS Ti6Al4V materials demonstrated higher yield strength than conventional Ti6Al4V. Both HIP'd DMLS and powder metallurgy specimens displayed lower modulus and yield strength that conventional material. The fatigue strengths exhibited by DMLS materials were drastically lower than those exhibited by materials fabricated with both conventional means and powder metallurgy. These lower fatigue strengths are attributed to significantly higher surface roughness and populations of internal pores in DMLS specimens, which were ameliorated by HIP. †

Mechanical Properties of Ti6Al4V Fabricated by Laser Powder Bed Fusion: A Review Focused on the Processing and Microstructural Parameters Influence on the Final Properties

“…On the contrary, when regarding tensile strain, Ti6Al4V fabricated by LPBF exhibits lower ductility when compared to cast or wrought [53]. As depicted in Table 3, several studies on LPBF Ti6Al4V parts show yield and tensile strengths that are significantly higher compared to the ASTM specification [33,41,53,72,106]; however, when regarding tensile strain, most of the studies report values lower than the minimum required (10%). This aspect is mainly the reason why heat treatments are usually performed on Ti6Al4V alloy fabricated by LPBF.…”