Several heat treatments were perfor

Several heat treatments were performed on Ti6Al4V produced bySLM with an original a0 microstructure. The influence of temperature, time and cooling rate were distinguished. When heated, aphase is precipitated at the a0 boundaries. At maximum temperatures below the b transus, the mixture of a and b phase preventsgrain growth and the original, columnar prior b grains remain visibleafter cooling. The width of the a plates after heat treatment is mainlydependent on the maximum temperature for sub-transus treatments, and primarily dependent on the cooling rate for super-transus treatments. The residence time and cooling rate do not have asignificant influence for sub-transus treatments, although theirinfluence increases when temperatures are closer to the b transus.When treated above the b transus, the columnar b grains growextensively to form large, semi-equiaxed b grains. For FC, AC andWQ samples, the b grains then transform to lamellar a + b, a-Widmanstätten colonies or a0 martensite, respectively. The residencetime influences the final dimensions of the transformed b grains.