Hot Dipped Galvanized Steel Roll / GI Coil Regular Spangle Zero Spangle Galvanized Coils

Galvanized Steel Coil is used cold rolled steel coil as substrates by a continuous hot-dip process. This method tightly adheres the coating to the steel with an iron-zinc alloy bonding layer formed by a diffusion process while the heated steel strip is in contact with the molten zinc. One of the drawbacks of Galvanized is that if the Zinc coating is scratched off the steel, the Steel is left unprotected, and is subject to failure. It has excellent corrosion resistance, paintability, and workability due to zinc’s characteristics.

When the nominal thickness of the product is greater than 0.50mm but less than or equal to 0.70mm, the elongation after fracture is allowed to decrease by 2%; when the nominal thickness of the product is not greater than 0.50mm, the elongation after fracture is allowed to decrease by 4%.

Galvanized steel coils production process:

1. Uncoiler
2. Welder
3. Entry Looper
4. Pre-treatment
5. Annealing Furnace
6. Zinc Pot
7. Cooling Tower
8. Water Quench Tank
9. Skin Pass
10. Tension Leveler
11. Passivation Coater
12. Exit Looper
13. Recoiler

The production and processing of galvanized steel coils can be divided into three steps: first, the entire coil is pickled to remove rust and dirt, so that the surface of the galvanized steel strip can achieve a bright and clean effect; after pickling, pass ammonium chloride or zinc chloride It is cleaned in an aqueous solution or a mixed aqueous solution of ammonium chloride and zinc chloride, and then sent to the hot-dip plating tank for the galvanizing process; after the galvanizing process is completed, it can be put into storage and packaged.

Types of zinc coating of galvanized steel coil

Hot-dip galvanized coils are divided into pure zinc coating and zinc-iron alloy coating according to the coating. Their common point is that the zinc content of the zinc solution in the zinc pot is the same. The difference is that the zinc-iron alloy adds an alloying process.

pure zinc coating

In the hot-dip galvanizing production line, the pre-treated steel strip is immersed in the molten zinc bath to obtain the coating. The zinc content in the molten zinc solution should not be less than 99%.

zinc-iron alloy

A zinc-iron alloy layer is formed on the entire coating through an alloying treatment process, and the iron content in the alloy coating is usually 8-15%. During the alloying process, the galvanized steel coil is heated to 550-560°C in an alloying furnace in 5-10 seconds, so as to convert all the pure zinc layer into iron-zinc alloy. Its weldability, coating performance, heat resistance, and corrosion resistance are better than ordinary galvanized sheets.

For example:

EN 10346 DX51D+Z is pure zinc;

EN 10346 DX51D+ZF is zinc-iron alloy coating.

American ASTM A653 standard Galvanized Steel Sheet & Coil

• Commercial Steel (CS Types A, B, and C)

Commercial Steel is a low-carbon cold-formed steel, such as galvanized steel roof forming

• Forming Steel (FS Types A and B)

Requires higher drawability than Commercial Steel, such as for lamp cover forming

• Deep Drawing Steel (DDS)
• Extra Deep Drawing Steel (EDDS)
• Structural Steel (SS) – (33,37,40,50,80)
• High Strength Low Alloy Steel (HSLAS)

European EN 10346 standard galvanized steel coil

Low carbon steel for cold forming (DX51D – DX54D)

• DX51D is equivalent to Commercial Steel, curved and profiled
• DX52D is equivalent to Forming Steel
• DX53D is equivalent to Deep Drawing Steel
• DX54D is equivalent to Extra Deep Drawing Steel

Structural Steels (S220GD – S350GD)

S220GD,S250GD,S280GD,S320GD,S350GD

Use structural steel for high load-bearing capacity, with a yield strength of 220-350

Galvanized steel coil Uses

Galvanized steel coil has a wide range of applications, and its advantage is that it has a long anti-corrosion period. It is mainly used for home appliances, office panels, roof sheets, automotive panels, construction and substrate of prepainted steel coils.

Car board

The use of automotive plates must first be stamped and formed, and the steel plate is stamped into the required shape and size of the part.

Then spot welding, as an important welding method for thin plate connection, has a wide range of applications in the manufacturing industry, especially in the automotive industry.

Galvanized roof sheet

The performance requirements of galvanized roof panels mainly include the mechanical properties of the material (tensile strength, yield strength, elongation), coating performance (coating type, coating thickness and coating adhesion)

Home appliance office board

Including air conditioners, washing machines, refrigerators, photocopiers, etc., household galvanized sheets are mainly used for general forming applications and stamping.

Substrate

Another use of galvanized steel coils is to be used as the substrate of prepainted steel coils. prepainted steel coils have polyethylene coatings than galvanized coils and are more durable.