Electrically assisted (EA) forming has ubiquitous merits over room-temperature (RT) forming and thermally aided forming for the fabrication of difficult-to-form microscale products. However, it is difficult to predict the material deformation behavior in the EA microforming process owing to the coupling between the electric current and microstructural size effect. To develop a robust constitutive model that considers the interplay between the electric and grain size effects, RT and EA quasi-static uniaxial tensile tests were performed on ultrathin nickel-based superalloy sheets with a thickness of 0.2 mm and grain sizes ranging from 27.2 to 79.4 μm. The experimental results demonstrated that the Joule heating effect and the normalized flow stress reduction were non-monotonically related to the grain size of the superalloy. The grain size effect in the polycrystalline superalloy was suppressed by the enhanced current density. A multiscale constitutive model that considered multiple strengthening mechanisms was proposed to describe the EA deformation behavior of ultrathin superalloy sheets. The multiscale model was proven to have a desirable predictive ability for the EA drawing force of thin-walled superalloy capillaries. Furthermore, the model revealed that the weakening of the grain size effect with increasing current density in the polycrystalline superalloy was caused by the combined variations in dislocation interaction, shear modulus, and strengthening mechanisms. The abnormal evolution of the surface effect with the current density was captured by the proposed constitutive model, which demonstrates that the electric current can promote the grain size effect in the multicrystalline superalloy.

与室温（RT）成形和热辅助成形相比，电辅助（EA）成形具有普遍的优点，可用于制造难以形成的微型产品。但是，由于电流和微观结构尺寸效应之间的耦合，很难预测EA微观成形过程中的材料变形行为。为了建立考虑电​​和晶粒尺寸影响之间相互作用的鲁棒本构模型，对厚度为0.2 mm，晶粒尺寸为27.2至79.4的超薄镍基高温合金薄板进行了RT和EA准静态单轴拉伸试验。微米 实验结果表明，焦耳热效应和归一化流应力的减小与超合金的晶粒尺寸非单调相关。多晶高温合金中的晶粒尺寸效应被提高的电流密度抑制了。提出了考虑多种强化机制的多尺度本构模型，以描述超薄超合金薄板的EA变形行为。事实证明，多尺度模型对于薄壁高温合金毛细管的EA拉力具有理想的预测能力。此外，该模型表明，随着位错相互作用，剪切模量和强化机制的综合变化，多晶高温合金中晶粒尺寸效应随电流密度的增加而减弱。提出的本构模型捕获了表面效应随电流密度的异常演变，