Grain size effect on springback behavior in bending of Ti-2.5Al-1.5Mn foils

The precise bend forming of metal foils is difficult, mainly because that the springback behavior cannot be easily controlled. In order to investigate the springback behavior in bending of metal foils, roll bending and pressure sizing tests were conducted on Ti-2.5Al-1.5Mn foils in this study. It has been observed that the springback behavior has a close correlation with the thickness to grain diameter (T/D) ratio and crystallographic texture. A certain critical T/D ratio value is observed, which divides the variation trend of the springback behavior into two different parts. Stress distribution is disturbed in specimens with small T/D ratio, which leads to large scatter of springback angle after unloading. Pressure sizing process can change the state of stress distribution of deformation region and it is a useful process to reduce the amount of springback angle and the scatter in bending of metal foils by controlling the sizing repetitions, sizing force, holding time and punch speed. Based on these findings, a micro scale honeycomb structure is successfully manufactured.