Softening effect of ultrasonic vibration on micro-blanking deformation behaviour of titanium foil

Owing to the advantage of softening effect, ultrasonic vibration has been widely applied in forming processes for many materials such as copper and aluminium. However, related study for hard-to-deform materials, e.g. titanium, is less reported. In the investigation, ultrasonic vibration assisted micro-blanking tests were carried out to improve surface quality of cross section for titanium foil (TA2) with a thickness of 0.2 mm. TA2 foil samples were annealed at different temperature to investigate the effect of ultrasonic vibration on deformation behaviour of materials with different grain sizes. The cross-sectional profiles of square parts blanked with and without ultrasonic vibration were analysed and compared using scanning electron microscopes. Experimental results show that the ratio of smooth zone decreases with the increase of grain size. When ultrasonic vibration is applied, the ratio of smooth zone is increased by the softening effect of ultrasonic vibration. For small grain size, the softening effect of ultrasonic vibration is more remarkable. It can be attributed to that TA2 foil with small grain size has more defects and could absorb more acoustic energy. The plasticity of the material is found to be improved from the morphology at the fracture zone. This finding can provide new insights for micro-blanking of titanium and expand the application of ultrasonic vibration.