Influence of high temperature exposure on fracture behaviors of TC11 titanium alloy

The tensile properties at room temperature of TC11 titanium alloy after high temperature exposure at different temperature and time are investigated. The variation and cause of fracture behaviors for TC11 titanium alloy after different high temperature exposure were analyzed. The results show that the tensile properties of TC11 titanium alloy are slightly affected when temperature is lower than 550°C, and the fractures consist of fiber zone and shear lip zone instead of radial zone. When temperature is beyond 550°C, the tensile elongation of TC11 titanium alloy decrease rapidly, and on fracture there is no fiber zone but only radial zone and shear lip zone. The radial lines converge to a pot adjacent sample surface. Mixed morphology characteristics of ductile ripple, quasi-cleavage and separation along phases and grains were found on radial zone instead of the isometric ductile ripple on fiber zone. Furthermore, quasi-cleavage and cleavage morphology were observed in shear lip zone. The fracture of TC11 titanium alloy after different high temperature exposure resulted from the notch effect of oxygen contamination layer, the precipitation of α₂(Ti₃Al) and the growth of secondary α and β.