The Effect of Heat Treatment on the Anisotropy of Ti-6Al-4V by Selective Laser Melting

In this work, the Ti-6Al-4V samples were prepared by selective laser melting. The effects of single annealing and double annealing on the microstructure and mechanical properties anisotropy of Ti-6Al-4V samples at room temperature were studied. The results showed that the morphology and structure of the α′/α phase changed significantly with an increase in the single annealing temperature, from the original slender needles to thick rod shapes. With an increase of the double annealing temperature, the α phase appears as short rod shapes, which have a tendency to be ellipsoid. The anisotropy of the sample can be significantly reduced by the two annealing methods. The 850–600°C double annealing sample shows a superior balance of tensile strength and elongation of 896(820) MPa and 13.2(13.8)% in the X-Y plane (X-Z plane), together with a minimal residual stress of 39.5 MPa.