Study of Size Effects on Deformation Behavior and Formability in Micro Metal Forming of Ti Foil

Micro forming technology becomes a promising approach to fabricate micro-parts due to its advantages of high productivity, low production cost, good product quality and mechanical properties, and near net or net shape characteristics. However, the deformation behaviors of material change and the so-called size effect occurs when the part dimension is decreased to micro-scale. To analyze the quality of micro-parts, the material flow stress, anisotropy, ductility and formability in micro-scale need to be considered. In the paper, micro tensile and micro deep drawing tests of Ti foils were used and the size effects on deformation behavior and formability of micro sheet metal forming were studied. The results show that the flow stress of Ti foils is related with foil thickness and grain size. The fracture behaviors also have been changed from shear dimple to slip separation with the decrease of foil thickness. The formability of micro deep drawing becomes worse with the decrease of micro cup dimension and the increase of grain size.