Effect of magnesium content on microstructure and corrosion behavior of hot-dip galvannealed steel

摘要

Galvannealed sheet (GA) is carbon steel sheet coated with zinc on both sides using a continuous hot dip process. The zinc coating with 10% iron is harder than a regular galvanized coating and is more resistant to scratching and improved spot-weldability, and allows for easier painting and improved coating adhesion. Galvannealed coatings provide excellent corrosion protection due to the sacrificial anode effect. The presence of 10% iron in the coating, however, can lead to a reddish-colored corrosion product. This stain is related to corrosion of the iron from within the coating, not steel substrate. Nevertheless, it is not easy for users to accept the staining.