Self-Study Program

21
This improvement of material properties by
subsequent heat treatment allows further
optimisation of weight.
The outer shell panels are dimensioned to
avoid permanent dents due to hailstones or
local pressure during polishing or when
closing doors/lids/tailgates.
Ancillary and outer shell panels
The materials used on the Audi A2 are mainly
heat-hardened. This is because they offer the
best compromise between good plasticity,
good mechanical properties and good anti-
corrosion properties.
After the material has been formed or the raw
body shell has been completed, the
properties of the material are changed by
heat treatment (205
o
C) in the body assembly
line. This improves mechanical properties
such as the apparent yielding point and the
tensile strength to give values comparable to
those achieved with conventional deep-drawn
steel.
SSP239_013
Rolled sheet metal
Extruded profile
Cast metal