Gi Sheet Central

What Is GI Sheet?

The full form of GI sheet is galvanized iron sheet. It is a kind of steel sheet that has been coated with zinc to prevent corrosion and prolong its service life. You can find galvanized plain sheets and galvanized profile sheets on the market. Considering the different galvanizing processes, we have hot-dip galvanized sheets and electro-galvanized steel sheets. Due to its excellent corrosion resistance and good appearance, it is a cost-effective choice in buildings, automobiles, furniture, home appliances, vessels, etc. Please keep reading for more details.

GI Sheet

GI Sheet

GI Plain Sheets

Galvanized Plain Sheets

GI Sheet Thickness

Galvanized iron sheet is a commonly used building material. The available GI sheet thickness at Wanzhi Steel is 0.2 -4mm. The popular thickness is 0.2-1.5mm. You can choose according to your needs. For example, the common thickness of decking sheets is 0.8-1.2 mm. While if you want to make CGI roofing sheets, you need to choose the GI sheet with 0.45-0.75 mm in thickness. Below is the GI sheet gauge chart.


What Is Galvanized Iron Sheet?

Galvanized iron sheet is a building material, which is made of mild steel sheet and coated with a layer of zinc on the surface. Galvanizing is an economical and effective anti-rust method that is often used. Its surface is smooth and shiny with big spangles, regular spangles, small spangles, or zero spangles.

Galvanized sheet weight calculator: Weight=7.85*length (m)*width (m)*thickness (mm)+ weight of zinc layer. (Density of steel = 7.85 g/cm3)

Here is an example: If the length is 2.3 m, the width is 0.95 m and the thickness is 0.35 mm. If the zinc coating is 100 g/m2. The steel sheet weighs about 6,22 kg. Besides, for the corrugated galvanized sheet, the width here refers to the overall width.

Galvanized Sheet with Big Spangles

GI Sheet with Big Spangles

Plain Galvanized Sheet Zero Spangles

Plain Galvanized Sheet Zero Spangles

Types of Galvanized Iron Sheet

There are different types of GI sheets. For example, due to the different galvanizing methods, there are hot-dip galvanized sheets and electro-galvanized steel sheets.

Hot dipped galvanized sheet is mainly produced by the continuous galvanizing process. That is, the zinc coating is applied by continuously immersing the steel coil in the molten zinc bath at temperatures of 450 degrees. This process provides a thick zinc coating that freezes into crystallized zinc spangles. The thick zinc coating offers full protection for the base steel. That’s why its service life is more than 30 years under normal conditions. By the way, the zinc layer at Wanzhi Steel is Z40-275 g/m2.

Electro-galvanized sheet often uses cold rolled steel as the base metal. Then the zinc coating of the electro-galvanized sheet is applied by electro-deposition. The continuous electrolytic coating process offers a thin but very uniform zinc coating. So the electro-galvanized steel has a smoother appearance. However, its corrosion resistance is not as good as that of hot-dip galvanized steel.

Hot Dipped Galvanized VS Electro-galvanized Steel

Appearance Difference

Plain & Corrugated Galvanized Sheets

According to the shape design, you can find plain galvanized iron sheets and corrugated galvanized sheets (CGI). The GI sheets are available from 1 to 12 m in width, 600-1,500 mm in width, and 0.12-2.5 mm in thickness. Plain GI sheets are suitable for back panels of home appliances and furniture. Also, they can be further processed for other uses, such as door panels, fencing, etc. Corrugated sheets are very widely used as roofing or wall panels. You can choose according to your use purposes.

Galvanized Plain Sheets

Galvanized Plain Sheets

Corrugated Galvanized Steel Sheets

Corrugated Galvanized Sheets

GI Sheet Uses

Galvanized steel sheet is a versatile product in various applications.

1. Construction industry — such as roofing sheets, wall panels, fencing, gutters, roof grills, balcony panels, window frames, warehouses, rolling doors, door panels, pipes, and much more.
2. Automotive industry — outer shells of car or tractor, bicycle frame, inner panels, bottom plates, container, highway fence, ship bulkhead, agricultural machinery, etc.
3. Light industry — shells and back panels of various household appliances, such as air conditioners, washing machines, refrigerators, microwave ovens, water heaters, chimneys, kitchen utensils, etc.
4. Furniture industry — wardrobe, table, bedside cabinet, file cabinet, bookshelf, and other uses;
5. Other uses — outdoor billboard, hopper, nuts, bolts, and nails, solar projects,  bucket, fermentation tank, and so on.

Below are some galvanized steel products made by Wanzhi Steel.

Galvanized Door Panels

Galvanized Door Panels

What Is GI Sheet


Advantages of Galvanized Steel Sheets

1. Excellent Corrosion Resistance

The zinc layer offers full protection of base metal, even in recesses or corners, which provides excellent corrosion resistance. The life expectancy is in excess of 30 years in most rural environments. But will galvanised steel sheet rust? Of course, yes. But it will be very slow.

2. Low Cost

Galvanizing is a low-cost protective coating for steel. Compared to galvalume steel, galvanized steel is cheaper. Besides, it requires less maintenance. In the long term, it is also very cost-effective.

3. Smooth Appearance

The galvanized sheet surface is smooth, shiny, and silver-white in color. So it can be used directly without other paintings or decorations. Besides, the galvanized coating also has good adhesion, which makes it also a great material for PPGI steel.

4. Wide Applications

It is popular in many industries, including automobiles, electrical appliances, construction materials, etc. The wide applications make it a great investment project as well. Also, we will offer discounts for bulk orders. Welcome to contact us for details.

Corrugated Galvanized Roof Package

CGI Roof Package

Corrugated Galvanized Roof Production

Corrugated Galvanized Roof Production

How Is Galvanized Steel Sheet Made?

1. Pre-treatment process (including pickling with alkaline solution) to remove the oil and other contaminants on the surface of the base steel.
2. Drying to improve the temperature to remove water on the surface of iron parts to avoid explosion during galvanizing;
3. Galvanizing. After being annealed, the zinc coating will be applied by immersing into a molten zinc bath at 445-455°C,  or electroplating. After a while, the surface of the steel will be covered with a zinc-iron alloy layer and zinc layer;
4. Cooling to form a stable zinc coating on the surface of the steel;
5. Grinding to remove residual zinc and zinc oxide compounds on the surface;
6. Quality inspection;
7. Cutting coils into sheets for sale.

Here you may have a better understanding of galvanized steel “What is GI sheet”. If you have other questions, you can contact us for more information. Wanzhi Steel is an experienced galvanized steel sheet manufacturer in China.

Hot-dip Galvanizing Process

Hot-dip Galvanizing Process


GI sheet is one of the hot-selling products of Wanzhi Steel. We have 3 continuous hot-dip galvanizing lines at our factory, which can produce 800,000 tons high quality galvanized sheets per year. We are specializing in the production and selling of GI steel with grades/materials SGCC, DC51D+Z/DX51D+Z, TDC51D+Z/AZ, etc. And the size is available in a thickness of 0.12-2.5 mm and a width of 600 to 1,500 mm. Also, we have cutting, sliting, and roller machines to provide plain and corrugated steel sheets. Besides, we also supply smoke pipes, ventilation pipes, door panels, and other galvanized products. Welcome to contact us for details!

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