Abstract:
Titanium alloy Ti5Al2.5Sn ELI is an important structural material in the field of aerospace and others. In the paper, the influence of casting process on the as-cast structure and tensile properties of titanium alloy Ti5Al2.5Sn ELI at room temperature was studied by pouring three kinds of mold with one furnace alloy. The results show that the surface of casting samples from graphite mold is rough, while that of the ceramic and metal mold is smooth; the macrostructure of samples from graphite mold is composed of numbers of equiaxed crystal and some columnar crystal, that of the metal mold is some equiaxed crystal and numbers of columnar crystal, and that of the ceramic mold is numbers of columnar crystal and little equiaxed crystal; the microstructure of the alloy under different processes is composed of irregular boundary α cluster, and the inner part is sheet α phase, and the width of α sheet of graphite mold is the smallest, that of metal mold is the second, and that of ceramic mold is the largest; the tensile strength of alloy is 715~731 MPa, the elongation is 8~15 %, the elongation of samples from the graphite mold is the highest, that of metal mold is the second, that of ceramic mold is the lowest, and the influence of molds on the elongation is obvious, but that on the strenths is little; the difference of surface morphology and thermal conductivity of mold, and the difference of α cluster size and α sheet thickness of samples are the main reasons for the phenomena.
