TC4钛合金超厚壁管斜轧穿孔后卡现象及双态组织控制

Control of Rear-jamming and Double-State Microstructure of TC4 Titanium Alloy Super-thick-walled Tube in Cross Piercing

在TC4钛合金超厚壁管斜轧穿孔过程中经常出现后卡现象,采用有限元模拟对其进行了分析。结果表明,后卡现象与内扩展率关系密切。当直径压下率大于10%,送进角大于12°和顶前压下率为5.8%~7.8%时,在稳态变形区内扩径率大于6%,此时可避免TC4钛合金超厚壁管后卡现象。采用正交试验法,在控制后卡的基础上,优选出成形过程中温度低于β相变点的工艺。确定的最优工艺参数为:送进角15°,直径压下率10%,顶前压下率7%。此时获得了双态组织的超厚壁管。

The phenomenon of rear-jamming often occurs in the process of cross rolling and piercing of TC4 titanium alloy ultra-thick wall tube.It was analyzed by using finite element simulation.The results show that the rear-jamming phenomenon is closely related to the internal expansion rate.When the diameter reduction ratio is larger than 10%,feeding angle is larger than12°and reduction ratio before the plug is 5.8%-7.8%,the inner expansion ratio in steady-state deformation zone is greater than6%,which can avoid the rear-jamming phenomenon of the ultra-thick tube of TC4 titanium alloy.On the basis of the controlled rear-jamming,the process that the temperature during the forming is lower than theβphase change point was obtained by orthogonal test.The optimum technological parameters are feeding angle of 15°,diameter reduction rate of 10%and reduction ratio before the plug of 7%.Under this process,the ultra-thick wall tube with double phase microstructure is obtained.