Being able to immediately tell if a piece of steel is galvanized or galvannealed is not an easy task, as the two look similar. Their essential difference pertains to the amount of iron found in one type over the other. Galvanized steel had zinc, with about 0.30 percent aluminum. Galvannealed steel, on the other hand, not only contains a small bit of aluminum, but it is also 10 percent iron. Those who work with steel often usually prefer galvanealed steel, which is better suited for spot welding and provides for better paint adhesion. If you're trying to figure out if a steel sheet is galvanized or galvannealed, follow the guidelines below.
Things You'll Need
Inspect the coating of the steel and if it's soft and easily scratched, it's most likely galvanized.
Can the steel sheet be formed into intricate shapes without any loss in coating adhesion to the steel? If so, it's galvanized coating.
Is the coating on the steel sheet hard, brittle? Is there powdering when the sheet is formed in a way that causes high compressive strain? If so, it's galvannealed steel.
If the sheet metal has signs of reddish-colored corrosion, it has a galvannealed coating. This occurs because of the iron in the coating, which is not found in galvanized steel.
Is the sheet of steel painted? If so, it's probably galvannealed, as most galvannealed steel is painted thickly in order to slow down corrosion.
Tips & Warnings
- If you're trying to decide whether you should use galvanized or galvannealed steel for a particular project, you will want to consider whether spot welding will be involved, whether it will be painted, and whether deep drawing will be involved.
- Never handle steel sheets without protective gloves, as the ends can be very sharp.