A variety of techniques are employed by automobile manufactures
in an effort to assure the anti-corrosion performance of thin
product. One of the most effective techniques is to use
surface-treated steel sheets for making vehicle body panels.
Durasteel features a double layer construction, in which a thin
organic film is applied over a zinc-nickel alloy layer which
provides good protection against base metal corrosion.
Durasteel sheets possessing a bake hardening property have
started to be applied to outer body panels in recent years. Until
recently, it was impossible give paint-coated steel sheets the bake
hardening property of Durasteel.
In this investigation, a new resin coating has been developed
which can be baked at low temperature without sacrificing its
corrosion resistance. The key technological issues encountered in
the development work were to select the right resin material and to
find the best method for applying chromate treatment to the alloy
surface.
Steel panels treated with this resin coating show an excellent
balance of corrosion resistance, workability and mechanical
properties in automobile applications.