Draw-Bending Formability of Steel Sheets in Hot Stamping Process

Deep drawability, which is one of the basic formability of sheet metal forming, was investigated in the hot stamping process. In order to clarify the basic property of deep drawing, the draw-bending forming without deformation at flange part was studied. In this report, the effect of the forming temperature and forming speed on the forming limit of draw-bending was examined. Numerical simulation was also employed for the discussion of forming mechanism. As a result, a critical part for fracture was non-contact part with the tools where the temperature was higher and the deformation resistance was lower than the surrounding area. The forming limit of draw bending increased with the lower forming temperature, the slower forming speed and the lower blank holder force. In these forming conditions, the temperature at a critical part for fracture was lower and the deformation resistance was higher than in other forming conditions. Accord-ingly, a temperature at the critical part for fracture was assumed to be a dominating factor over draw-bending formability in hot stamping process.