Deformation path and springback behavior in double-curved bending at high temperature

In this work, integrated double-curved bending-sizing-unloading is simulated for a Ti6Al4V titanium alloy sheet. Bending radii R30 mm × R30 mm and R30 mm × R15 mm are used in the bending tests at 700 °C and 750 °C, respectively. A holding time of 0–600 s is applied to explore the effect of sizing time on forming accuracy. Similar experimental tests are performed for comparison with the finite element analysis results. Results show that bending behavior varies remarkably with the bidirectional radii. As for equal bidirectional curvature, bending along each direction occurs simultaneously. Given that bidirectional radii are different, the sheet consecutively experiences single small-, single large-, and double-curved bending. The deformation path results in nonuniform plastic strain distribution. The springback amount increases from the center to the marginal middle zone. Sizing at 700 °C or 750 °C in 600 s or 180–600 s can remarkably reduce the springback amount, respectively. The springback prediction via finite element method is consistent with that of the experiment.