Decoding Galvanized Steel Coil Codes: A Comprehensive Guide

The codes associated with galvanized steel coils represent a standardized way to convey essential details about their composition, surface treatment, mechanical properties, and intended applications. Here's a detailed breakdown of these codes and their meanings:

1. Material Type

Material type codes specify the type of steel and its intended use. These are defined by international standards like JIS (Japanese), EN (European), ASTM (American), or GB (Chinese).

• SGCC, SGCH (JIS G3302):

SGCC: Commercial quality galvanized steel, suitable for general applications like roofing or cladding.

SGCH: High tensile strength galvanized steel for structural uses, often in construction.

• DX51D, DX52D, DX53D (EN 10346):

DX51D: Basic commercial-grade galvanized steel for general-purpose applications.

DX52D: Higher ductility, suitable for deeper drawing and forming.

DX53D: Deep-drawing quality, ideal for intricate shapes.

• G30, G60, G90 (ASTM A653):

Used in American standards, with the number referring to zinc coating weight in ounces per square foot.

2. Zinc Coating Weight

The zinc coating weight refers to the thickness of the zinc layer applied to the steel, measured in grams per square meter (g/m2) on both sides.

• Z100: 100 g/m2 coating (50 g/m2 per side).

Z275: 275 g/m2 coating (137.5 g/m2 per side). Commonly used for outdoor applications requiring good corrosion resistance.

• Z600: 600 g/m2 coating (300 g/m2 per side). Suitable for highly corrosive environments.

The zinc coating protects the steel from rust and extends its service life. Heavier coatings provide better corrosion resistance but may increase the material's cost.

3. Surface Finish

The surface finish describes the visual appearance of the galvanized steel and may also affect its performance for specific applications.

Normal Spangle (N): A crystalline pattern visible on the surface, typical for galvanized steel.

Minimal Spangle (M): A finer, smoother surface suitable for applications requiring uniform finishes, such as painting.

Zero Spangle (ZF): A completely smooth surface with no visible pattern, often used in applications demanding a flawless finish.

4. Surface Treatment

Surface treatments enhance the material's resistance to corrosion, improve adhesion for painting, or provide a specific aesthetic quality.

• Chromated (C): The steel is coated with a chromium compound to increase corrosion resistance.
• Non-Chromated (NC): Environmentally friendly option with no chromium treatment.
• Passivated: A chemical treatment that forms a protective layer to resist rust.
• Non-Passivated: No additional chemical treatment applied.

Other optional treatments include oiling or applying anti-fingerprint coatings to protect the surface during handling and storage.

5. Mechanical Properties

Mechanical properties determine the material's strength and flexibility, making it suitable for different applications.

• Yield Strength: The stress at which the material begins to deform. Common values include 280 MPa, 350 MPa, etc.
• Tensile Strength: The maximum stress the material can withstand before breaking, e.g., 500 MPa, 600 MPa.

These properties are especially critical in structural or load-bearing applications.

6. Thickness and Width

• 0.5mm x 1250mm: Indicates the thickness (0.5mm) and width (1250mm) of the coil.

Typical thickness ranges: 0.2mm to 3.0mm.

Typical widths: 600mm to 1500mm.

This information ensures that the product fits the specific requirements of a project.

7. Coil Type

• Full Hard: The steel has not been annealed after galvanizing, resulting in higher strength but lower flexibility.
• Soft/Annealed: Heat-treated to improve flexibility and workability for forming or shaping.

Example Code Breakdown

Example 1: DX51D+Z275-M-A

DX51D: General-purpose galvanized steel.

Z275: 275 g/m2 zinc coating (137.5 g/m2 per side).

M: Minimal spangle (smooth surface).

A: Indicates oiled and chromated surface for added corrosion resistance.

Example 2: SGCC+Z100-N-O

SGCC: Commercial quality galvanized steel for general use.

Z100: 100 g/m2 zinc coating (50 g/m2 per side).

N: Normal spangle (visible pattern).

O: Oiled to prevent rust during handling and storage.

8. Common Applications Based on Codes

SGCC, Z275, N: Roofing sheets, cladding, general construction.

DX52D, Z100, ZF: Automotive panels, home appliances, precision components.

SGCH, Z600, M: Structural supports, industrial projects, heavy-duty applications.

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