Galvannealed steel is coated with a Zinc-Iron
Alloy by a process known, in the metallurgical
technology, as the Hot-Dip Process. This process
consists of passing cold reduced sheet steel in
coil form continuously through a pot of molten
zinc. As the steel leaves the pot, the amount of
coating allowed to remain on the sheet is
controlled by coating rolls which are used to
establish minimum coating weights in accordance a
ASTM Designation A525/A525M. The zinc coating is
what protects the steel against corrosion. This
protection acts in two ways. The zinc acts a s a
shield between the base steel and the atmosphere
and when the base steel is exposed, such as at
sheared or blanked edges, the zinc acts a galvanic
protector, sacrificing itself in the presence of
corrosive elements. The coating structure
consists of a layer of zinc superimposed on a thin
alloy layer consisting of both iron and zinc. The
solidification of the zinc layer results from
crystallization of the bath metal.
Galvannealed products are increasingly in demand.
They are found in a wide variety of applications
requiring long-term maintenace-free corrosion
protection, such as, bridges, pulp and paper mill,
recreation centers, utility industries, oil
refineries and petrochemical industries,
automobile industry, and for miscellaneous highway
uses, such as guard rails, lights, signs and
fencing. Why in so many applications? Because
galvannealed products offer the most economical
corrosion protection for steel.
Why you should specify ‘galvannealed’ steel:
Purchasing cost of sheet metal is competitive.
Reduced preparation and painting costs.
Provides considerably longer life-expectancy.
Delivers excellent resistance to corrosive
Offers superb paind adhesion characteristics.
Requires minimal maintenance.
Galvannealed, when used without further treatment,
offers the most economical corrosion protection
for steel in many environments. The coating left
on the steel is dull gray in color. It has no
spangle and, after proper cleaning, is well suited
for painting. The zinc coating makes an excellent
base on which to develop a paint system.