Galvanized Steel Coil Types
According to the processing method, we divide galvanized steel into the following categories:
1. Hot-dip Galvanized Steel Coil (Z)
As the name implies, the steel sheet is immersed in the molten zinc bath continuously so that the coil is covered with a layer of zinc on its surface. Hot-dip galvanizing is immersing the cleaned iron sheet into the molten zinc bath at about 450 degrees to form a zinc layer. The zinc content should not be less than 99%. It is the most commonly used method. It has some advantageous features:
1) The entire steel surface is uniformly covered with a zinc layer, even the corners, hollows, etc. so that the steel sheet is fully protected.
2) The zinc coating of hot dip galvanized steel is thick and tough, which offers superior corrosion resistance. So it is more durable to use. At Wanzhi Steel, the maximum zinc layer thickness can reach up to 275 g/㎡.
But after continuous annealing and hot-dip galvanizing, the steel coil is heated and cooled in a short time so that its strength and plasticity are affected to a certain extent.
2. Zinc-Iron Alloy Galvanized Steel Coil (ZF)
This kind of steel coil is also manufactured by the hot-dip galvanizing process. But it is heated to about 500 ℃ immediately to form an alloy coating of zinc and iron after it is out of the zinc bath. This galvanized coil has good coating adhesion and weldability. That is, it can be painted directly without further treatment, other than cleaning. The color is matt off-white, and it appears dark gray after oiling and it has no spangles. It is perfect for making rolling shutters, signboards, panels of vending machines, refrigerators, washing machines, display cabinets, office cabinets, etc.
3. Electro-galvanized Steel Coil
Electro-galvanizing is a process of applying a layer of zinc to steel through electroplating, with a saline anode and steel conductor. It basically ensures the same performance as cold rolled sheets through cold galvanizing. Also, it is able to enhance the corrosion and heat resistance of steel. Its surface is smooth and uniform, and it has good workability. Also, it looks shiny and silver-white, which is more beautiful than a hot-dip one. Moreover, it is cheaper than hot-dip galvanized steel. However, the zinc coating is thinner, and the corrosion resistance is not as good as that of hot-dip galvanized coils.
Specifications of galvanized steel coils：
| Product | Galvanized Steel Coils/Sheets-GI |
| Material | DX51D,DX52D,DX53D,DX54D,SGCC,S250GD-S550GD |
| Width | 30-1500 mm |
| Thickness | 0.1-6.0 mm |
| Type of Coating | Hot-Dipped Galvanized |
| Zinc Coating | Z30-Z600(g/m²) |
| Surface Treatment | Chromed/Skin Pass/Oiled/Slightly Oiled/Dry |
| Spangle | Zero Spangle/ Regular Spangle |
| Coil Weight | 3-10 tons per coil or as requirements |
| Grade | Yield Strength/Mpa | Tensile Strength/Mpa | Elongation/% |
| DX51D+Z | ≤360 | ≤440 | ≥20 |
| Dx52D+Z | ≤260 | 330-390 | ≥28 |
| DX53D+Z | ≤200 | 270-320 | ≥38 |
| DX54D+Z | ≤180 | 270-310 | ≥40 |
| S250GD+Z | ≥250 | ≥330 | ≥19 |
| S350GD+Z | ≥350 | ≥420 | ≥16 |
| S450GD+Z | ≥450 | ≥510 | ≥14 |
| S550GD+Z | ≥550 | ≥560 | / |
