一种可在低温高应变速率下超塑成形的钛合金研究及其开发

Study of a Superplastic Forming Titanium Alloy at Low Temperature and High Strain Rate

研制出一种以 Ti2 Co相弥散强化 α- Ti基体的钛合金 Ti- 8Co- 5 Al。实验表明 ,在变形温度为 72 5℃ ,应变速率为 1× 10 - 3s- 1 的条件下可获得断裂延伸率 70 8%。从实测应变速率敏感性指数为 0 .47,并结合试样断口处纵向剖面显微组织的扫描电镜观察 ,表明在Ti- 8Co- 5 Al合金中发生了α- Ti晶界及α- Ti/ Ti2 Co相界的滑移为主要变形机制的变形过程。采用 Ti- 8Co- 5 Al合金在 730℃和 1× 10 - 3s- 1 应变速率条件下成功地等温锻造出飞机零件 ,比 Ti- 6 Al- 4V合金低约 2

An alloy Ti 8Co 5Al with an ultra fine α Ti+Ti 2Co microstructure is newly developed which exhibits 708% superplastic elongation at 725℃ and 1×10 -3 s -1 strain rate. In terms of the examinations of the strain rate sensitivity ( m ≈0 47, and fracture, the deformation mechanism of the alloy during superplastic deformation is grain and phase boundary slidings. The alloy Ti 8Co 5Al has been successfully isothermoformed, and some aircraft components have been obtained at isothermoforming temperature of 730℃ (210℃ lower than thermoforming temperature of the alloy Ti 6Al 4V).