Deformation behavior of pure titanium foils in ultrasonic-assisted tensile forming process

The deformation capacity of foils deteriorates rapidly due to the appearance of size effects. In this study, the mechanism of ultrasonic vibration affecting the tensile deformation behavior of pure titanium foil was investi-gated using the developed ultrasonic-assisted tensile forming platform. The results showed that the energy of ultrasonic vibration during foil tensile deformation was mainly consumed by acoustic softening and mechanical vibration, and the energy consumed by acoustic softening was less than 20% of the total energy. When the percentage of grain boundary region is less than the critical value, increasing the ultrasonic amplitude results in a slight increase in the percentage of acoustic softening energy, but a sharp decrease in elongation. The digital image correlation results showed that the acoustic softening effect promoted the dispersion of local concentrated deformation of foils, resulting in more uniform deformation. Mechanical vibration could accelerate the formation and propagation of microcracks, which makes the fracture morphology of foils exhibit brittle fracture charac-teristics. Foil grain refinement is a useful method to enhance the acoustic softening effect during the tensile deformation process of foils. This work provides a basis for investigating the mechanism of ultrasonic vibration affecting the tensile deformation behavior of foils.