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 alpha '/alpha 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 alpha 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 degrees 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.