What Are Galvanized Sheet and Electro-Galvanized Sheet?
Many industries use steel sheets for various applications. However, the main problem is that steel sheets, when exposed to moisture and oxygen, undergo corrosion and rusting. To solve this problem and increase the lifespan of metals used in industry, a process must be carried out on them. For this reason, galvanizing or zinc-coating of steel sheets is used.
Electro-galvanized steel sheets are one type of galvanized sheets. In this article, we intend to discuss in more detail what electro-galvanized sheet is. So, to get better acquainted, continue with us as we introduce electro-galvanized sheet, explain its production method and applications, and review its differences with hot-dip galvanized sheet.
This article examines the following topics:
What Is Galvanized Sheet?
To understand what electro-galvanized sheet is, we must first define galvanized sheet. Galvanized sheet (G) is produced from sheets obtained from the cold rolling or hot rolling production line. In order to protect against corrosion and rusting, a coating layer is applied to the sheet.
In this method, a layer of zinc (Zn) is placed on the outer surface of the sheet, and it is called zinc-coating. Galvanizing sheets produced from the rolling line provides the advantage that moisture and oxygen cannot reach them, thus increasing their lifespan.
The lifespan of galvanized sheet can reach about 20 to 50 years, depending on the environmental conditions of use and the thickness of the zinc coating. In addition to resistance against rusting, galvanized sheets are paintable, formable, and shapeable. It should also be noted that galvanized sheets are recyclable and reduce environmental impact.
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Types of Galvanized Sheets
The production process of galvanized sheet is not limited to dipping in molten zinc. Galvanized sheet has different types in terms of coating and production method, which we will introduce here.
1. Hot-Dip Galvanized Sheets
These sheets are called hot-dip galvanized because the galvanization process takes place at high temperatures. The steel sheet from the hot or cold rolling production line is immersed in a bath of molten zinc. The temperature of molten zinc is about 450°C. This sheet has a rough and dark surface and a thickness in the range of 0.4 to 3 mm. Hot-dip galvanized sheet, which has high resistance, is used in outdoor applications such as construction structures.
2. Electro-Galvanized Sheets
For producing electro-galvanized steel sheets, molten zinc and high temperature are not used. Instead, a thin layer of zinc is applied to the sheet surface using an electric current. Electro-galvanized sheet, also known as plated galvanized sheet, has a smooth and shiny surface and can be painted easily. Since electro-galvanized sheet has an attractive appearance, it is used in manufacturing home appliances and electrical enclosures. The difference between hot rolling and cold rolling lies in the process temperature and the quality of the final product.
3. Galvalume Sheet
Galvalume sheet, or Aluzinc, is coated with an alloy of zinc-aluminum, which provides high resistance and durability against oxidation, rusting, and corrosion. The alloy composition of Galvalume sheet consists of 55% aluminum, 43.5% zinc, and 1.5% silicon. Silicon preserves adhesion of the coating and increases bending and tensile capacity. Other features of Galvalume sheet include resistance to discoloration under high heat and welding, temperature resistance, heat reflection, and having a protective surface without the need for chromating. Due to its suitable appearance and high resistance, Galvalume sheet is used in architecture and roofing. Other applications include making water heaters, exhausts, cabinets, refrigerators, coolers, door and window profiles, etc.
4. Galfan Sheet
Galfan sheet is also coated with a zinc-aluminum alloy, with the difference that the aluminum content in Galfan sheet is higher than in Galvalume sheet. Galfan sheets have high thermal resistance. They are suitable for use in agriculture, automotive, infrastructure, and environments with high humidity, as well as marine and coastal applications. Sheets produced from hot or cold rolling, coated with zinc-aluminum alloy, are turned into Galfan sheets.
5. Galvannealed Sheets
Galvannealed sheets are stronger than galvanized sheets because, after the galvanizing process, they undergo annealing. During this, a layer of zinc-iron alloy is formed on the sheet surface. Galvannealed sheets are more durable and resistant compared to galvanized sheets, and they have higher weldability. Due to heat treatment, paint adhesion is improved and highly suitable. Galvannealed sheets are used in applications requiring high tensile stress, automotive body and frames, and marine equipment.
What Is Electro-Galvanized Sheet?
After defining galvanized sheet and introducing its types, now let us see what electro-galvanized sheet is. As mentioned earlier, electro-galvanized sheet is a black sheet or cold-rolled sheet, obtained from hot and cold rolling, and coated with a thin layer of zinc using electro-deposition.
Electro-galvanized steel sheets are smooth and uniform, with high resistance against corrosion and rusting. Easy paintability, high weldability, and high formability are among other features of these sheets. Next, we will explain the production method and applications of electro-galvanized sheet.
Production Method of Electro-Galvanized Sheet
Here we discuss the production method of electro-galvanized sheet. Among the types of steel sheets (st), oily sheet is the basis of galvanized sheet production. The production of electro-galvanized sheet is such that an electric current is passed through a solution of zinc sulfate or zinc cyanide, and a very uniform and thin layer of zinc is deposited on the steel sheet surface. Thickness during production is controllable.
Electro-galvanized sheets have a smooth and thin surface, and the thickness of the zinc coating is less than that of hot-dip galvanized sheets. In the rolling line, there are rollers that need periodic grinding to maintain performance and prevent damage to the produced sheets.
Applications of Electro-Galvanized Sheets
After introducing electro-galvanized sheet and explaining its production method, let us see its applications. Due to their rust-resistance, corrosion resistance, smoothness, and paintability, electro-galvanized steel sheets are used in various industries, such as:
- Automotive: car body, gas tank
- Construction: apartment facades, building frames, house doors, outdoor metal parts such as balconies and porches
- Agriculture: agricultural equipment, heavy farming machinery
- Home Appliances: refrigerators, dishwashers, washing machines
- Road Construction: traffic signs
- Electronic Equipment: electrical boxes, audio systems, DVD players, electrical enclosures, and various products such as wires, bolts, nuts, etc.
What Are the Differences Between Electro-Galvanized Sheet and Hot-Dip Galvanized Sheet?
After introducing electro-galvanized sheet and explaining its production method and applications, the question arises: what is the difference between hot-dip galvanized sheet and electro-galvanized sheet? The first difference lies in their production method. Hot-dip galvanized sheet is zinc-coated at high temperature using molten zinc, while electro-galvanized sheet is coated by electro-deposition using a zinc sulfate solution, without heating.
In the production process, a thicker zinc coating is applied on hot-dip galvanized sheet, while the coating on electro-galvanized sheet is thinner. For this reason, hot-dip galvanized sheets are more expensive and more corrosion-resistant than electro-galvanized sheets. In addition, the lifespan of hot-dip galvanized sheets is longer than that of electro-galvanized sheets.
Electro-galvanized sheets have smoother, shinier, and more uniform surfaces, with straight edges and precise tolerances, unlike black sheet, which has common defects that affect final product quality. Hot-dip galvanized sheets, on the other hand, have darker and rougher surfaces. This difference also results in different applications.
For example, electro-galvanized sheet, due to its better appearance, is more suitable for decorative purposes. Hot-dip galvanized sheet, however, is more suitable for environments with harsher climates and corrosive agents. Although electro-galvanized sheets are less expensive than hot-dip galvanized sheets, they may be sold at higher prices due to lower supply and higher demand.
Conclusion
In this article from Mazs Group, we discussed what electro-galvanized sheet is. Today, most industries use steel sheets. Sometimes it is necessary for steel sheets to resist moisture, rust, and corrosion, and this is where the process of zinc-coating or galvanizing becomes important.
Electro-galvanized steel sheets are a type of galvanized sheet. As we explained, in their production method no heating is involved, and galvanization is carried out using electro-deposition and zinc sulfate solution.
FAQ
Depending on environmental conditions and the thickness of the zinc coating, the lifespan of galvanized sheets can range from 20 to 50 years.
They are produced by passing an electric current through a zinc sulfate or zinc cyanide solution, depositing a uniform and thin layer of zinc on the steel sheet surface.
They are widely used in automotive manufacturing (car bodies, gas tanks), construction (facades, frames), home appliances (refrigerators, washing machines), agriculture, road signs, and electronic equipment (electrical boxes, audio systems).
Electro-galvanized steel is steel coated with a thin, uniform layer of zinc using an electroplating process to improve corrosion resistance and surface finish.
Galvanized steel is coated with zinc by hot-dip immersion, giving thicker corrosion protection, while electro-galvanized steel uses electroplating to apply a thinner, smoother zinc layer with a better surface finish.
No, electro-galvanized and galvanized are not the same; electro-galvanized has a thinner, smoother zinc coating applied by electroplating, while galvanized steel has a thicker coating applied by hot-dip galvanizing for higher corrosion resistance.
