Abstract:In order to improve the low cycle fatigue property of selective laser melting Ti-6Al-4V alloy,the effects of heat treatment on the microstructure and properties of selective laser melting Ti-6Al-4V alloy were studied by using OM,SEM,TEM,room temperature tensile and low cycle fatigue tests.The results show that the as-built microstructure is characterized by epitaxially grown β columnar grains and acicular martensite α" with a certain orientation in the grains.After annealing,α" decomposes and transforms into basket-weave α+β.After cyclic heat treatment,lath α becomes globularized,and the microstructure is composed of equiaxed α, lath α and residual β.After heat treatment,the low cycle fatigue property of the annealed state reaches more than 87% of the forgings,which reaches more than 90% of the forgings for the cylic heat treated state.