🟧 Product Overview

Hot‑dip galvanized steel coil (HDG) is produced by immersing cold‑rolled steel in a molten zinc bath, forming a metallurgical bond between zinc and steel.

The zinc coating provides three layers of protection:

1. Barrier Protection – prevents direct exposure to moisture and oxygen
2. Cathodic Protection – zinc sacrifices itself to protect exposed steel
3. Self‑Healing on Cut Edges – zinc reacts to protect scratches and cut edges

This makes HDG one of the most widely used corrosion‑resistant steel products worldwide.

🟧 International Standards

ASTM A653 (USA)

• G40 / G60 / G90
• CS / FS / DDS / EDDS

EN 10346 (Europe)

• DX51D / DX52D / DX53D
• Z120 / Z150 / Z180 / Z275

JIS G3302 (Japan)

• SGCC
• SGCD1 / SGCD2 / SGCD3

GB/T 2518 (China)

• Z‑series zinc coatings

🟧 Global Zinc Coating Matrix

System	Coating	Zinc Mass (g/m²)	Typical Use
ASTM	G40	120	Indoor, light duty
ASTM	G60	180	General construction
ASTM	G90	275	Roofing, outdoor, high corrosion
EN/GB	Z120	120	Indoor, ducting
EN/GB	Z150	150	Light outdoor
EN/GB	Z180	180	General outdoor
EN/GB	Z275	275	Roofing, structural, coastal

🟧 Base Steel Grade Matrix

Standard	Grade	Description	Formability
EN 10346	DX51D	General structural	★★★
EN 10346	DX52D	Forming quality	★★★★
EN 10346	DX53D	Deep drawing	★★★★★
JIS G3302	SGCC	Commercial quality	★★★
JIS G3302	SGCD1	Drawing quality	★★★★
JIS G3302	SGCD2/3	Deep drawing	★★★★★

🟧 Zinc Coating Structure (Layer Description)

The galvanized coating consists of three metallurgical layers:

• η‑Layer (Pure Zinc Layer) – primary corrosion protection
• ζ‑Layer (Zinc‑Iron Alloy Layer) – strong adhesion
• δ‑Layer (Transition Alloy Layer) – improved wear resistance

This layered structure ensures excellent corrosion resistance, adhesion, and processing performance.

🟧 Product Specifications

Dimensions

• Thickness: 0.12 – 3.0 mm
• Width: 600 – 1500 mm
• Coil ID: 508 / 610 mm
• Coil Weight: 3 – 10 MT

Surface Finishes

• Regular spangle
• Zero spangle
• Mini spangle
• Chromated / Non‑chromated
• Oiled / Dry
• Skin‑passed

🟧 Mechanical Properties (typical)

Grade	Yield Strength	Tensile Strength	Elongation
DX51D	140–300 MPa	270–500 MPa	≥ 22%
DX52D	140–260 MPa	270–420 MPa	≥ 26%
DX53D	120–220 MPa	260–380 MPa	≥ 30%
SGCC	205–380 MPa	270–550 MPa	≥ 16%

🟧 HDG vs. Alu‑Zinc vs. Color Coated (Comparison)

Property	HDG (Zinc)	Alu‑Zinc (55% Al‑Zn)	PPGI / PPGL
Corrosion Resistance	★★★	★★★★	★★★★★
Heat Resistance	★★★	★★★★★	★★★
Paint Adhesion	★★★★	★★★★	★★★★★
Cost	★★	★★★	★★★★
Best Use	Structural, roofing	Coastal, high‑corrosion	Decorative, roofing, appliances

🟧 Applications

Construction

• Roofing sheets
• Wall panels
• Purlins
• Rainwater systems

HVAC

• Air ducts
• Ventilation systems

Home Appliances

• Refrigerator panels
• Washing machine bodies

Automotive

• Body panels
• Structural reinforcements

General Manufacturing

• Electrical cabinets
• Furniture
• Storage systems

🟧 How to Choose the Right HDG Coil (Buyer Guide)

✔ Choose Zinc Coating

• Indoor → Z120 / G40
• General outdoor → Z180 / G60
• Roofing / Structural → Z275 / G90
• Coastal / High corrosion → Z275 minimum

✔ Choose Base Steel Grade

• DX51D / SGCC → General structural use
• DX52D / SGCD1 → Forming applications
• DX53D / SGCD2/3 → Deep drawing

✔ Choose Surface Finish

• Zero spangle → Appliances, façade panels
• Regular spangle → Structural and industrial use

🟧 FAQ

Q1: Are G90 and Z275 the same?

Yes. Both represent approximately 275 g/m² zinc coating, but from different standards.

Q2: What is the difference between DX51D and SGCC?

They are equivalent grades from different standards (EN vs. JIS).

Q3: Can galvanized steel be painted or color‑coated?

Yes. HDG is commonly used as the base material for PPGI.

Q4: What is the difference between zero spangle and regular spangle?

Zero spangle offers a cleaner appearance for appliances and façade panels; regular spangle is used for structural applications.

🟧 Why Choose WelSteels

• Full range of G‑series and Z‑series zinc coatings
• Stable mechanical and surface quality
• Advanced galvanizing lines
• SGS / BV inspection available
• Export‑grade seaworthy packaging
• Reliable delivery for global projects