Effect of Phase Transformation Conditions on the Microstructure and Shear Performance of TB8 Titanium Alloy

Phase transformation of TB8 titanium alloy was studied under different heat treatment conditions; the effects of microstructure and phase composition on shear performance were investigated by microstructure characterization and fracture analysis. Results show that the heat treatment condition will affect the microstructure of TB8 titanium alloy, and also affect the shearing deformation behavior. With increasing of solution temperature, the size of grains increases obviously, the morphology of the precipitates also changes, and the starting of shearing deformation becomes difficult. The subsequent aging temperature after solution treatment will obviously influence the shearing deformation behavior of the alloy. After solution at 840 °C for 1 h followed by aging at 450 °C for 8 h, the driving force required for shear deformation will be decreased; when the subsequent aging temperature increases to 550 °C or more, shear fracture cut through grains. According to the results of shear tests, the alloy solutioned at 840 °C for 1 h followed by 500 °C/8 h aging can achieve an excellent shear performance with a reasonable microstructure.