Fracture toughness of ZTi6Al4V casting titanium alloy under different annealed conditions

The theory of notch strength was used to judge the damage tolerance capability of ZTi6Al4V casting titanium alloy, for example, the effect of annealing temperature on three-point bending fracture toughness. The results show that fracture toughness K _Q1, which was tested by notched specimens, is not equal to the K _Q tested by the standard testing method. But it was used to compare qualitatively fracture toughness of casting titanium alloy with different annealing processes. The changing of annealing temperature can adjust strength and fracture toughness of ZTi6Al4V casting titanium alloy. Samples annealed at 700°C and 800°C for 2 h have better toughness, the K _Q values are 78.11 MPa·m ^1/2 and 79.44 MPa·m ^1/2. They also have a relatively better match of strength and plasticity, that is the yield strength is up to 782.74 MPa and 771.49 MPa, tensile strength reaches 860.18 MPa and 853.0 MPa, and the elongation reaches 8.10% and 7.46% respectively.