Page 6 - MFi Vol.152 ATZ Extra Issue 2019
P. 6

                                Aluminum alloys used in automobiles : 1
                01              Aluminum alloy sheet

                                   Aluminum alloy sheet features superior formability and strength

                 6000 series aluminum alloy sheet for body panels

            Producing body panels from aluminum alloy sheet is a highly effective way to   Change in proof stress from during forming
            reduce weight and enhance fuel efficiency.                           to after coating
            Currently, 6000 series aluminum alloy sheets are the type most commonly   6000 series sheets are strengthened more
            used in body panels, and since they have “bake-hardenability,” they can be   than 5000 series sheets.
            strengthened during the coat baking process.
            The 6000 series aluminum alloy sheets are characterized by low strength               When shipped
            during the molding process, making them highly workable, but the coat                 After 2% pre-straining
                                                                                                  After 2% pre-straining
            baking process makes them substantially stronger.                     Proof stress    20 min. at170°C

                          properties of   Hemmability
                          automobile    Dent resistance                                 6000  5000  5000  5000
                          body sheet                                                    series  series  series  series
     Motor Fan illustrated
                                        Corrosion resistance                         Change in proof stress of body sheets
                                        High-luster paint finish

               The LEXUS LS door panels (inner/outer)



                                                                                      IK This photograph shows how
                                                                                      deeply the alloy was drawn to
                                                                                      produce this inner door panel. 6000
                                                                                      series aluminum alloys are used for
                                                                                      both the inner and outer door panels
                                                                                      of the LS.

               Bonnet of Toyota Prius                                                    Ordinary aluminum sheet

                                                                                         High-hemmability sheet

                                                         Since aluminum alloy sheet is less elongate than steel sheet, it cracks easily
                                                         during hemming. This means that flat hemming involving bending by 180
                                                         degrees has previously been difficult to achieve. However, UACJ Corporation
             Both the interior and exterior structures are made from 6000   has created an aluminum alloy sheet that can be subjected to Sharp Hemming,
             series aluminum alloy sheet.                a process that is even more problematic than flat hemming.
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