Coupled effect of pulsed current and ultrasonic vibration on deformation behavior of Inconel 718 sheet: phenomena and modeling

Multi-energy fields provide higher dimensional precision control and desirable performance for microforming processes. The constitutive model under low strain level was established to describe the coupled effect of pulsed current and ultrasonic vibration based on the Kocks-Mecking (K-M) model. Combined with the crystallographic theory, the model introduced acoustic softening effect and electroplastic effect, and described the interaction between pulsed current and ultrasonic vibration under coupled field from the perspective of energy absorption. In the research, the uniaxial tensile test of Inconel 718 sheet with thickness of 0.3 mm was carried out. The ranges of the current density and ultrasonic energy density were 20.9–50.9 A mm⁻² and 15.84–57.64 J cm⁻³, respectively. The results showed that: the facilitation of ultrasonic vibration on dislocation generation was limited with the increase of strain, and the energy generated by ultrasonic vibration was more reflected in the change of Helmholtz free energy; when the energy generated by the current at athermal condition tended to be saturated, the increase of heat became the key to improve the electroplasticity, and the heating model caused by Joule heating effect was established. The constitutive model of coupling electric pulse and ultrasonic treatment was established, combining the characteristics of ultrasonic vibration and pulsed current; the flow stress was described by using the parameters of ultrasonic energy density and current density; The trigonometric function was used to quantitatively describe the competitive relationship between ultrasonic vibration and pulsed current in external work. Two sets of experiments were used to demonstrate the reliability of the model.