Abstract Electrically assisted stretch U-bending tests have been conducted in this research to analyze the influence of electrical parameter duty cycle cycle on the springback of Ti6Al4V sheets. It is found 30% duty cycle brings about 50% increase in residual height of split angle of U-bending specimen compared with that obtained in room temperature. Meanwhile, 30% duty cycle causes additional 13% effect on springback relief than that treated in 10% duty cycle at the same temperature, which indicates elevated temperature alone is insufficient to account for overall decrease on springback during the treatment of electric current. Subsequent electrically assisted stress relaxation test under the same condition gives further explanation on the decrease of springback in short period numerically. Microstructure evolution observed in both tests illustrates grain growth along with dislocation motion activated by thermal expansion results in stress softening in the duty cycle less than 20%. As for the duty cycle of 30%, the precipitated αʹ phase reveals that the accelerated phase transformation α→β can provide additional stress drop and such observation is also certified by hardness investigation conducted in this research.

中文翻译：

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电脉冲对Ti6Al4V钛合金板U形弯曲拉伸回弹的影响

摘要 本研究通过电辅助拉伸U形弯曲试验，分析了电气参数占空比对Ti6Al4V板回弹的影响。结果表明，与室温下相比，30%的占空比使U形弯曲试样的分裂角残余高度增加了约50%。同时，在相同温度下，30% 占空比对回弹消除的影响比在 10% 占空比下处理的额外增加 13%，这表明单独升高温度不足以解释电流处理过程中回弹的整体降低。随后在相同条件下进行的电辅助应力松弛试验对短周期回弹的减小给出了进一步的数值解释。在两个测试中观察到的微观结构演变说明晶粒生长以及由热膨胀激活的位错运动导致占空比小于 20% 的应力软化。对于 30% 的占空比，析出的 αʹ 相表明加速相变 α→β 可以提供额外的应力降，这一观察结果也得到了本研究中进行的硬度调查的证实。