These days, automobile industry tends to use aluminum alloy sheets to reduce weight of auto-body. However, aluminum alloy sheets have the drawback that they have tremendous springback in press forming operations. Springback deteriorates accuracy of the product as well as causes difficulties in assembling the parts such that technical plans for springback reduction before pressing have to be prepared. In this paper, the warm forming method, which changes material properties, is proposed to decrease springback. In order to suggest the warm forming method, first, the material properties of aluminum alloy sheets, AL1050 and AL5052, in high temperatures such as yield stress, plastic strain ratio, Young's modulus, true stress-strain curve, etc. are obtained from tensile tests. Next, the bending and draw bending tests in various forming temperatures are performed to measure the springback in various forming temperatures. Two kinds of experiment show that the springback tremendously reduces in warm forming, specially in the forming temperatures of above 150oC.

Keywords: Springback, Worm forming aluminum alloy sheets, Tensile test in high temperature, Stretch bending, Draw bending