Coated steels are steel sheets that have a metallic and/or non-metallic coating to prevent rust and corrosion that humidity and contamination can cause on the steel.
Coated steel has an extra layer of metal, paint, or both to protect it from rust and wear. It is ideal for those who are looking for resistant, aesthetic, light, and cost-effective materials in industries such as construction, automotive, white goods, and other growing sectors.
Steel Coating Process:
- The basis of most coated steel is cold-rolled steel.
- The sheet is covered with a metallic and/or non-metallic coating to prevent rust and corrosion that humidity and contamination can cause on the steel.
- Metallic coatings can consist of a zinc layer (Zintro) or alloys of zinc and other materials such as aluminum (Zintro Alum).
- Galvanization can be done by immersion in molten metal or by electrochemical processes.
- The process starts with the placement of cold-rolled steel sheets.
- The edge of each roll is trimmed to remove imperfections.
- Then, it goes through alkaline or direct flame cleaning process to eliminate residues such as oil or particles.
- The sheet is then transported to a continuous annealing furnace to recover structural properties and ductility.
- It is then immersed in a molten metal crucible in which coating is adhered to; excess liquid metal is swept off with air or gas.
- Finally, the sheet is given a surface finish, treated with a chemical solution to protect the coating, a thin layer of oil oxide is applied, and then it is rolled.
- Electrogalvanization consists of immersing the material in an electrolytic solution of zinc chloride and passing an electric current through it.
- The current passage causes the zinc to adhere to the surface of the steel sheet and coat it.
- Non-metallic coatings such as paint form a film that protects and embellishes the alloy when it dries (Pintro).
Cut and Finish
- The production process ends with the cut or form into rolls, sheets, and strips of rectangular, square, circular, and triangular designs, among others.
- In addition, surface finishes and other treatments can be applied for specific uses.
The main coating types used by Ternium are:
Zintro: The steel sheet is subjected to galvanizing, a hot-dip process to add a layer of zinc to prevent corrosion. As it is a high-resistant and economic option, it is commonly used in precarious and rural environments.
Zintro Alum: The steel piece is coated with zinc and aluminum to combine the properties of both metals in a sheet capable of resisting six times more corrosion than the normal galvanizing, as well as reflecting heat. It is used in industrial units and facades.
Pintro: After galvanizing, the sheet is coated with paint on one or both sides. In addition to extending the life of the sheet and maintaining the room temperature, this coating offers an aesthetic finish ideal for white goods and architectural applications.