Abstract:The effect of heat treatment on microstructure and tensile properties of EBM Ti–45561 was investigated. The as-build material exhibited columnar β grains epitaxially grew along z direction, which is caused by the temperature gradient during the solidification process. Acicular α phase precipitated inside each β grains due to the 730℃ environment temperature. With the increase of post-build annealing temperature and extension of annealing time, the grain boundary α phase and secondary α phase were both coarsened. When the solution treat temperature was increased, the percentage of primary α phase decreased. Among the 3 heat treatment parameters, the annealing temperature has the strongest influence on tensile properties, and the annealing time has the smallest influence. The elongation of the EBM Ti–45561 increased with annealing temperature; while the strength of the material decreased with annealing temperature.