Produced on continuous lines similar to hot dip galvanizing, cold rolled sheet steel is hot dipped into molten aluminum or an aluminum alloy containing 5-10% silicon. It has excellent resistance to high temperature oxidation and offers good heat reflectivity. At surface temperatures up to 950°F the steel base is protected although some surface darkening may occur.
Although in most environments the long-term corrosion rate of aluminum is only about 15-25% of that of zinc, the protective value of aluminum on steel is a function of its coating thickness and its tendency to remain intact, thus providing long-term protection. Type 1 (ASTM A463), light coating, is recommended for welding and drawing applications.
Type 1, regular or commercial has approximately a 1 mil-thick coating on each surface, offering excellent heat resistance. Type 2, with approximately a 2 mil-thick coating on each side is often used for atmospheric corrosion resistance.
Designations And Weights Of Aluminum Coating On Aluminized Steel Sheet (A)
||Minimum Coating Weight (c)
|T1 25 (light)
|T1 40 (regular)