Page 6 - MFi Vol.152 ATZ Extra Issue 2019

ALUMINUM
AUTOMOBILE TECHNOLOGY
ALUMINUM
MATERIAL
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

Bake-hardenability
Formability
Required
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)

ALUMINUM AUTOMOBILE TECHNOLOGY

06

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

Hemming
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.