The surface of steel sheet can be coated with a zinc compound prior to reheating in an annealing process. Zn atoms diffuse into the Fe to create a Zn-Fe series alloy. This process is referred to as Galvanealing.
SPM & Chemical Treatment
In order to achieve a flat surface and elegant finish, the steel sheet is processed with a skin pass mill. In order to prevent the white rust, which often forms on the surface of activated zinc, and to improve corrosion resistance, the surface is coated with a Cr-free resin.
Inspection & Coiling
Located at the line’s exit section are a side trimmer, inspection table and oil coating equipment. At this station all products are inspected and judged relative to material specifications required by the client.
Some rolling oil and other contaminants remain on the surface of cold-rolled steel sheets following processing. These are removed by passing the electrically charged sheet through an alkaline solution which induces an electro-chemical reaction.
The material properties of pre-treated steel sheet can be altered and improved through recrystallization during the annealing process
After passing through the annealing furnace, steel sheet is dipped into a zinc pot where molten Zn is coated onto the surface. The desired coating weight is achieved by removing excess zinc before solidification with high pressure air from an air knife.