Hot V-bending behavior of pre-deformed pure titanium sheet assisted by electrical heating

The whole hot V-bending process assisted by electrical heating (EH) of pre-deformed pure titanium sheet, from initial cyclic bending-unbending deformation to EH of sheet, followed by hot V bending and further rebound after unloading, were systematically studied by experiments and FEM numerical simulations. Besides, the differences and corresponding mechanisms in heating efficiency and bending behavior between EH and furnace heating (FH) were compared and analyzed. Specifically, the 1-mm-thick sheets were subjected to three passes of cyclic bending-unbending with 90^o bending angle and 5 mm punch radius. Subsequently, the sheets were electrically heated with a series of current intensities, 50, 100, 150, 200, 250, 300, and 350 A, and bent after heating. The microstructures in different characteristic layers after cyclic deformation were observed; the temperatures varying with heating time under various current were measured and the heating efficiency was referred to FH in corresponding ambience temperatures. Additionally, the heat transfer situation of samples to the die in bending and its effect on springback after unloading were discussed. The variation of bending force to punching stroke of the samples heated by both modes, combined with their underlying mechanisms of difference, was tested and analyzed.