热处理对TC4ELI 钛合金板组织与力学性能的影响

Effect of heat treatment (750 ℃ for 1-4 h or 750-900 ℃ for 1 h)on microstructure,mechanical properties and fracture morphologies of TC4ELI titanium alloy plate was investigated by means of OM,SEM and tensile test. The results indicate that the rolled TC4ELI titanium alloy plate and the one after heat treatment show notable anisotropy in transverse and longitudinal direction. The primary α grains of the rolled TC4ELI alloy plate have good equiaxedness in transverse direction,while they are elongated in longitudinal direction. When heating at 750 ℃,the grains grow bigger with more time. As the heat treatment temperature increases from 750 ℃ to 850 ℃,the content of primary α phase increases,the grain size increases,and the morphology becomes equiaxed. When the heat treatment temperature reaches 900 ℃,a small amount of primary α phase transforms into β phase,resulting in the decrease of primary α phase content. Furthermore,the tensile properties of the TC4ELI titanium alloy plate in longitudinal direction are significantly lower than those in the transverse direction,and the yield ratio in transverse direction is slightly higher than that in the longitudinal direction. Heat treatment does not change this trend. By comprehensive comparison,the microstructure and mechanical properties of the TC4ELI titanium alloy plate heated at 850 ℃ for 1 h are the optimum.