摘要
目的研究电脉冲周期对管材成形性能的影响。方法对成形温度进行热电耦合数值分析,寻找到合适的电脉冲参数。对TA2钛合金管材进行了电脉冲辅助气胀成形实验,研究电脉冲周期管材胀形率、形状误差系数、微观组织、显微硬度分布的影响,分析电脉冲辅助胀形过程中动态再结晶现象。结果随着电脉冲周期的增大,管材膨胀率增大,形状误差率减小。当电脉冲周期增大到30 s时,膨胀率达到最大值42.7%,形状误差率仅为0.259%;电脉冲作用下,管材温度曲线呈现出明显的锯齿状上升,电能转化的温升与计算结果相近;EBSD观察发现材料在较低的温度(600℃)下发生了动态再结晶现象,组织细化,塑性提高。结论随着电脉冲周期的增大,管材塑性提高,环向变形均匀性得到改善。低频电脉冲的引入使TA2钛合金再结晶温度降低,晶粒发生细化。
The paper aims to study influences of electric pulse period on forming performance of tube. Thermoelectric coupling values of forming temperature are analyzed to find out proper electropulsing parameters. The effects of expansion ratio, shape deviation ratio, microstructure and microhardness distribution of the forming tubes were analyzed through electropulsing-assisted gas forming experiment on TA2 titanium alloys. Dynamic recrystallization in the electropulsing-assisted gas forming was analyzed. The results showed that with the increase of the electric pulse period, the expansion ratio of the tube was enlarged, and the shape deviation ratio was decreased. When the period of electric pulse increased to 30 s, the expansion rate reached the highest value of 42.7% and the shape deviation ratio was only 0.259%. The temperature profile presented a serration shaped growth under the action of electric pulse. The temper ature rise was consistent with the calculation results. The electron backscattered diffraction(EBSD) results showed that obvious dynamic recrystallization occurred at a lower temperature(600 ℃). Meanwhile, the grains were refined and the plasticity was improved. The conclusion is that with the increase of the electric pulse period, the plasticity of the tube is improved, and the uniformity of the circumferential deformation is also improved. The temperature of dynamic recrystallization of TA2 titanium alloy is decreased and the grain is refined with the introduction of low frequency electropulsing.
作者
陈剑
汤泽军
陶克梅
CHEN Jian;TANG Ze-jun;TAO Ke-mei(College of Mechanical and Electrical Engineering,Nanjing University of Aeronautics and Astronautics,Nanjing 210016,China)
出处
《精密成形工程》
2019年第1期11-16,共6页
Journal of Netshape Forming Engineering
基金
国家自然科学基金(51105203)
关键词
电脉冲
TA2钛合金
气胀成形
微观组织
electropulsing
TA2 titanium alloy
gas forming
microstructures
