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U. S. Steel GALVALUME® Steel Sheet is carbon steel sheet
coated with aluminum-zinc alloy by a continuous hot-dip
process described in Production
Methods. The nominal coating composition is 55% aluminum and
45% zinc. A small but important addition of silicon is included in
the coating alloy. It is added not to enhance the corrosion
performance, but to provide good coating adhesion to the steel
substrate when the product is roll-formed, drawn, or bent during
fabrication.
 GALVALUME® steel sheet combines the
excellent barrier corrosion protection of aluminum with the
galvanic protection of zinc. The result is a coating that lasts a
long time, a coating that provides cut-edge protection along
sheared edges, and therefore, a coating that offers excellent
protection to steel sheet. Although there are a few exceptions, for
most applications in most types of environment, GALVALUME®
steel sheet is the preferred product when long-term resistance to
atmospheric corrosion is desired. It outlasts a galvanized coating
of comparable thickness, and offers cut-edge protection that is not
available with aluminum-coated sheet. This cut-edge protection
means there is less rust-staining along sheared edges, at
scratches, and other imperfections in the coating. Also, since the
coating is so resistant to corrosion, it retains a very bright
surface appearance when exposed to most atmospheres. These
attributes make GALVALUME® steel sheet the preferred material
for roofing.
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The
superior corrosion resistance of GALVALUME® steel sheet is
achieved by the presence of microscopic zinc-rich and aluminum-rich
areas within the coating. The aluminum-rich areas, which corrode
very slowly, provide the long-term durability while the zinc-rich
areas, which corrode preferentially, provide galvanic
protection. |
GALVALUME® is a registered trademark of BIEC
International, Inc.
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