Different Types of GI Sheets
GI sheet is short for galvanized iron sheet, which is one of the most used steel materials in the world for homes, businesses, buildings, industries, automobiles, and so on. It is steel that has been coated with zinc to prevent corrosion to prolong its service life. According to the different classification standards, there truly exist different types of GI sheets. Let’s have a review of them now!
Manufacturing Method
Due to the different galvanizing processes, it can be divided into hot-dipped galvanized sheets and electro-galvanized sheets. Keep reading for the different types of GI sheets, please.
Hot Dipped Galvanized Sheet (HDG Sheet)
HDG steel sheet is mainly produced by the continuous hot-dip galvanizing process. Hot-dip galvanizing is a process of coating base metal with a zinc layer, which serves as a barrier between the steel and the environment. The finish is applied by passing the steel through a molten bath of zinc at a high temperature. That is, the steel will be put into the molten zinc bath at temperatures of 500 degrees to form a close alloy film. This process provides a thicker zinc coating, about 30-275 g/m2, and can freeze into crystallized zinc spangles.
There is also a kind of zinc-iron alloyed galvanized steel sheet. This kind of steel plate is also made by the hot-dip galvanizing process, but immediately after it is out of the tank, it is heated to about 500 ℃ to form an alloy film of zinc and iron. This kind of galvanized sheet has good paint adhesion and weldability.
When exposed to the atmosphere, pure zinc reacts with oxygen to form zinc oxide. This further reacts with carbon dioxide to form zinc carbonate, a dull grey, fairly strong material that stops further corrosion in many circumstances, protecting the steel below from the elements.
Uses
Hot dipped galvanized steel sheet functions well in applications throughout a variety of industries in which parts are exposed to corrosive chemicals and harsh conditions. These industries include construction, automotive, agriculture, military and defense, transportation, and manufacturing.
Electro Galvanized Sheet (EG Sheet)
EG sheet, also known as cold galvanized steel sheet, uses electrochemical devices to adhere to a zinc layer. Electro-galvanized steel is carbon steel with a corrosion-resistant zinc coating applied to one or both of its sides by electro-deposition. The continuous electrolytic coating process covers the steel surface with an exceptionally uniform thickness, which can enhance forming and joining operations. It offers a thin but uniform zinc coating, about 10-50 g/m2. So its corrosion resistance is not as good as that of hot-dip galvanized steel sheet.
In addition, the cold galvanized steel sheet has a smooth, matte appearance similar to the cold rolled sheet. Thus, the surface quality is exceptionally good for applications that require a high finish after painting, such as automotive panels. The excellent control of the coating thickness that is achieved with the electrolytic deposition process is beneficial to enhancing forming and joining operations, especially by contributing to more reliable results from automatic and robotic welding systems. Both the zinc and zinc-iron electro-galvanized coatings are readily paintable, but to achieve good resistance to corrosion, the coated-steel surface should be pretreated and primed prior to application of the finish paint coating.
Uses
More applied in indoor places and environments that require less corrosion resistance but higher beauty aesthetics. Industries include automobiles, furniture, home appliances, vessels, electronic equipment, commerce, etc.
According to Spangles
Due to the different treatment methods in the coating process, the appearance of the galvanized sheet is also different, such as regular spangle, small spangle, and no spangle. The galvanized sheet should have a good appearance without defects that are harmful to the use of the product, such as no plating, holes, cracks and scum, over-plating thickness, scratches, chromic acid dirt, and white rust, etc.
Spangle is the visible aesthetic feature of crystallites on the surface of a galvanized steel sheet. The spangle appears as either a snowflake or a six-pointed star pattern. This is produced on the steel sheet when certain alloying elements are either added to the liquid zinc or available as impurities. Spangle sizes on galvanized steel sheets are classified as regular, small, or zero spangles.
Surfaces with spangles have lower corrosive and mechanical resistance properties as compared to the uniform zinc-iron alloy surface. Sheets with spangles are suitable for many ordinary applications. However, spangles are undesirable when painting or when the use of an outer layer of synthetic plastic is required for finishing or decorative purposes.
Regular spangles are obtained by condensation of the zinc layer under normal conditions after galvanizing. While the fine spangle galvanized sheet is formed by artificially restricted during the solidification process of the zinc layer. And the spangle-free coating is obtained by adjusting the chemical composition of the plating solution and has no visible spangle morphology and a uniform coating on the surface. It is important to note that the spangles will influence the appearance but will not influence its features.
According to Thickness
Thickness is an important factor for steel strength and durability. According to the thickness, we have different types of GI sheets. But considering the different environmental usage requirements, we have thin galvanized steel sheets and medium and thick galvanized steel plates.
Thin GI Sheet: 0.2-4 mm
Medium and Thick Galvanized Plate: Above 4 mm
Generally, the former has a thinner and more precise dimension. Thus, it is widely used in light industry, furniture, home, automobiles, etc. The latter is much thicker and heavier, more suitable for construction, bridge, shipment, mechanical engineering, etc.
Plain or Profiled Sheet
According to the shape design, it can be distinguished as corrugated galvanized steel sheet and plain galvanized steel sheet.
Corrugated Galvanized Sheet (CGI Sheet)
It takes GI sheets as material and then profiles them into corrugated patterns with a roller mill, which will increase the bending and malleability strength of steel. They eventually come in different forms such as trapezoidal, wavy, ribbed, and tile designs. Sometimes, it is also in the form of a flat sheet. At Wanzhi teel, our CGI sheets are available from 1 to 12 m in width, 600-1,500 mm in width, and 0.12-2.5 mm in thickness. You can choose according to your use purposes.
This corrugated galvanized panel is a tough material, lightweight, weather resistant, and practical for many different uses. We specialize in manufacturing top-quality corrugated materials for metal roofing, metal siding, corrugated metal decking, and corrugated metal flooring for almost any application.
Whether you’re reviving a storage facility or building a new stable, galvanised roofing sheets could be the ideal solution. Formed into an iconic, traditional roof sheet profile, they’re crafted from hot-dipped galvanized steel which will provide superb durability for years to come. Featuring corrugations, these galvanised sheets are both strong and cost-effective. The most commonly used galvanised roofing sheets are 0.5mm and 0.7mm in thickness. This makes these galvanised sheets a truly customisable option that will save you both time and money in labor costs.
Plain GI Sheet
Plain galvanized steel sheet is a metal sheet coated with protected metallic and organic zinc coatings, with no extra deformed design.
Uses
Extensively used in the automobile, transportation, construction, home appliances, and civil engineering industries. It can work as the trunk, back panel, or boards. Also, it can be further processed for other uses, such as PPGI sheet/coil, corrugated GI sheet, fencing, steel piping, etc.
Differences Between GI Sheet and GL Sheet
There is a kind of metal very similar to GI sheet, called galvalume sheet (GL sheet). GL sheet refers to a sheet of metal that has been coated in galvalume; a carbon steel base product is repeatedly hot-dipped into the alloys of aluminum and zinc. The coating the metal ends up ensures the product is made up of 55% aluminum, 43.4% zinc, and 1.6% silicone. Galvanized metal refers to a sheet of metal that has been coated with zinc via hot-dipping. The combination of zinc and aluminum in Galvalume enhances both the positive and negative effects of aluminum. Galvalume has barrier corrosion resistance and heat resistance similar to aluminized material and good bare edge galvanic protection and forming qualities like galvanized material. Consequently, Galvalume and Galvalume Plus will resist rust, the elements, and fire while providing a sturdy and protective covering.
Conclusion
Wanzhi Steel is the largest manufacturer and exporter of galvanized steel coils and sheets in China. We have hot-dip galvanizing line and cold galvanizing line to offer different types of GI sheets for sale. Also, we have the equipment to make galvanized plain and corrugated sheets for sale. The whole range of offered products is fabricated with high precision by using premium quality raw materials and modish techniques. They are high in strength, corrosion-resistant, eco-friendly, durable, and lightweight. Except galvanized sheet, we also use GI sheets as the base metal of the PPGI sheets. If you want to know more details, welcome to contact us now!
