Mechanical Anisotropy of Ti-6Al-4V Alloy Fabricated by Selective Laser Melting

Abstract:

To explore the formation mechanism of anisotropy in Ti-6Al-4V alloy fabricated by selective laser melting (SLM), the compressive mechanical properties, microhardness, microstructure, and crystallographic orientation of the alloy across different planes were investigated. The anisotropy of SLM-fabricated Ti-6Al-4V alloys was analyzed, and the electron backscatter diffraction technique was used to investigate the influence of different grain types and orientations on the stress-strain distribution at various scales. Results reveal that in room-temperature compression tests at a strain rate of 10^-3 s^-1, both the compressive yield strength and microhardness vary along the deposition direction, indicating a certain degree of mechanical property anisotropy. The alloy exhibits a columnar microstructure; along the deposition direction, the grains appear equiaxed, and they have internal hexagonal close-packed (hcp) α/α' martensitic structure. α' phase has a preferential orientation approximately along the <0001> direction. Anisotropy arises from the high aspect ratio of columnar grains, along with the weak texture of the microstructure and low symmetry of the hcp crystal structure.