Galvanized Steel Sheet & Coil

Galvanized steel sheet & coil are steel sheets or strips with a zinc or zinc alloy coating formed on their surface through a continuous hot-dip galvanizing process, using hot-rolled or cold-rolled steel strips as the substrate. The product is available in two forms: steel sheet (supplied in flat form) and steel strip (supplied in coil).
The core value of galvanized steel sheet & coil lies in their dual anti-corrosion mechanism, achieved through a physical barrier and electrochemical protection via the zinc coating. The zinc layer acts as a sacrificial anode, protecting the base steel from corrosion even when the coating is partially damaged, resulting in corrosion resistance far superior to ordinary cold-rolled sheets. The product has an attractive surface with blocky or leaf-like crystalline patterns, a strong coating, and excellent resistance to atmospheric corrosion.

Galvanized steel sheet & coil can be classified in several ways, including by substrate type, coating type, zinc spangle type, and application.
1. Classification by Substrate Type

2. Classification by coating type

3. Classification by zinc flower type

According to production and processing methods, galvanized steel sheets can be divided into the following categories:
1. Hot-dip galvanized steel sheets: Thin steel sheets are immersed in a molten zinc bath, causing a layer of zinc to adhere to their surface. Currently, continuous galvanizing is mainly used, where coiled steel sheets are continuously immersed in a zinc bath to produce galvanized steel sheets.
2. Alloyed galvanized steel sheets: These are also manufactured using the hot-dip method, but after removal from the bath, they are immediately heated to approximately 500°C to form an alloy coating of zinc and iron. These galvanized sheets have good paint adhesion and weldability.
3. Electro-galvanized steel sheets: These galvanized steel sheets are manufactured using electroplating and have good workability. However, the coating is thinner, and their corrosion resistance is not as good as hot-dip galvanized sheets.
4. Single-sided and differentially galvanized steel sheets: Single-sided galvanized steel sheets are products galvanized only on one side. They have better adaptability than double-sided galvanized sheets in terms of welding, painting, rust prevention, and processing. To overcome the drawbacks of uncoated galvanized steel sheets, a type of galvanized sheet with a thin layer of zinc coated on the other side is available; this is called a double-sided differential galvanized sheet.
5. Alloy and composite galvanized steel sheets. These are steel sheets made by alloying or compositing zinc with other metals such as lead and zinc. These steel sheets possess both excellent rust resistance and good paintability.

In addition to the above five types, there are also color-coated galvanized steel sheets, printed galvanized steel sheets, and PVC laminated galvanized steel sheets. However, hot-dip galvanized sheets remain the most commonly used.

Performance Advantages of Galvanized Steel Sheet & Coil
1. Excellent Corrosion Resistance: The galvanized layer forms a dual mechanism of physical barrier and electrochemical protection on the steel surface. Hot-dip galvanized steel coils have a thicker galvanized layer, resulting in excellent corrosion resistance. Under normal conditions, the rust-proof layer can last for 15-30 years.
2. Good Processing and Forming Performance: Galvanized steel sheet & coil possess both good weldability and cold forming performance. Different grades correspond to different stamping levels, satisfying requirements from general bending to ultra-deep drawing.
3. Good Surface Quality: Galvanized steel sheet & coil have a smooth and aesthetically pleasing surface and can be finished with various surface morphologies such as normal zinc spangle, small zinc spangle, or no zinc spangle. Surface coating treatments are available, supporting RAL colors and custom patterns such as wood grain/brick texture.
4. Economical and Practical: Galvanized steel sheet & coil combine excellent corrosion resistance with moderate cost, making them one of the most cost-effective anti-corrosion steels.
5. Main Limitations
Weldability is slightly inferior to cold-rolled steel: the galvanized layer is easily damaged during welding, requiring careful process control.
Drawing performance is less reliable than cold-rolled steel.

Applications of Galvanized steel sheet & coil
1. The application of the construction industry
In the construction industry, galvanized coil is commonly used in the manufacture of building materials such as roofs, walls, pipes, steel structures, beams, and columns. Galvanized coil for steel structures has the advantages of light weight, high strength, fire prevention, anti-corrosion, etc. It is widely used in the construction of stadiums, conference centers, commercial centers, and other buildings.
2. The application of the automobile industry
Galvanized coil in the automotive industry is used as a car shell, doors, chassis, energy-saving panels, and other parts of the material. Due to its advantages of high strength, high toughness and corrosion resistance, it can improve the safety and durability of automobiles and is environmentally friendly.
3. The application of the home appliance industry
In the home appliance industry, galvanized coil is used as a manufacturing material for refrigerators, air conditioners, washing machines, water heaters and other home appliances. Galvanized coil can meet the appearance of home appliances, strength, corrosion resistance, and other requirements, and can reduce production costs and improve product competitiveness.
4. The application of the packaging industry
Galvanized coil is also widely used in the packaging industry, such as the manufacture of food cans, cosmetic cans, paint cans, and so on. Galvanized coil has good corrosion resistance and sealing, can ensure the quality and safety of the packaging, while improving production efficiency.

Galvanized steel sheet & coil possess excellent corrosion resistance, good processability and formability, and are economical and practical, making them widely used in construction, automotive, home appliance, container, and transportation industries. Currently, galvanized steel sheet & coil are continuously developing towards thinner specifications, more diversified coatings, and more functionalized surfaces.

Galvanized steel sheet & coil is a type of steel coil that has been coated with a layer of zinc to protect it from rust and corrosion.The following are some common national standards for galvanized sheet coils in China, Britain, the United States and Japan:

1. Chinese national standard:
GB/T 2518-2019: Continuous hot-dip galvanized steel sheets and strips

2. British National Standard:
BS EN 10327:2004: Technical delivery conditions for galvanized coated steel sheet and strip
BS EN 10326:2004: Continuous hot-dip galvanized steel strip and plate

3. American National Standard:
ASTM A653/A653M-20: Standard Specification for Hot-Dip Galvanized Steel Sheet and Strip
ASTM A924/A924M-20: General requirements and supply requirements for hot-dip galvanized coated steel sheet and strip

4. Japanese national standard:
JIS G 3302:2019: Hot-dip galvanized steel sheets and strips

The standard allowable error of galvanized sheet coils is usually specified in detail in national standards or industry standards. These standards specify tolerances in size, shape, surface quality, etc. of galvanized coils to ensure that the product meets specifications and quality requirements.

The specification of galvanized sheet is usually expressed by multiplying the thickness by the width, among which the thickness of galvanized sheet is mostly 0.4-3.2 mm, and the width is mostly 1000-1500 mm. The more common galvanized sheet specifications are 0.4×1000mm, 0.6×1000mm, 1.5×1000mm, 0.45×1250mm, 0.7×1250mm and so on. There will be a certain deviation in the production process of galvanized sheet. Generally, the greater the thickness, the greater the deviation, and the deviation of length and width is generally about 5 mm. The following is an example of the size and error range that may be involved under normal circumstances.

1. Thickness: The thickness of common galvanized sheet coils ranges from 0.4mm to 4mm. The allowable error is usually around 0.01mm to 0.05mm.
2. Width: The width of galvanized sheet coils is usually between 600mm and 1500mm, and there may be larger or smaller specifications. The allowable error is generally between ±2mm and ±10mm.
3. Length: The allowable deviation is about 5mm

These dimensions and deviations are general examples, actual product dimensions and deviations may vary depending on specific applications and standard requirements

The new national standard adopts a more systematic method of designating grades. Common grades include:

Taking DX51D+Z as an example—D (cold rolling), X (unknown), 51 (grade number), D (stamping), +Z (pure zinc coating).