Effect of Annealing on Microstructure and Tensile Property of Cast TG6 High-temperature Ti-based Alloy

The microstructure and mechanical properties of high temperature titanium alloy TG6 under different conditions such as cast state,hot isostatic pressing and annealing treatment were studied.The results shows that the microstructure of the as-cast alloy is coarse Widmanstaten with shrinkage porosity,and the resulting tensile strength is 871.3 MPa,while the elongation is only 0.8%.It is found out that shrinkage porosity acts as crack initiation source.The tensile strength and elongation increase to 871.3 MPa and 0.8% respectively after HIP.The banded and granular（TiZr）₆Si₃ silicide phase precipitate in β lathes after annealing at 750 ℃,and β lathes dissolve partially.The ductility at room temperature improves to more than 5% after annealing,with no significant change of tensile strength compared to that of HIP,and the tensile fracture surface indicates the characteristics of cleavage fracture.