S550GD Steel Grades
High-Strength Galvanized Structural Steel for Construction and Industrial Applications
- Technical Support
S550GD Steel Technical Specifications & Applications
S550GD is a high-strength hot-dip galvanized structural steel grade compliant with EN 10346, offering a minimum yield strength of 550 MPa. It combines superior strength, formability, and corrosion resistance, making it suitable for demanding applications in construction and manufacturing.
This steel grade is widely used in structural framing, purlins, and heavy-duty roll-formed sections. Its excellent weldability and cold-forming properties allow for efficient processing in bending, cutting, stamping, and roll-forming operations.
Manufactured under stringent quality controls, S550GD meets international standards, ensuring reliable performance in galvanized and structural steel applications.
As a core product of Hengze Steel Group, S550GD is trusted globally for durable, high-performance galvanized structural steel solutions in construction, engineering, and manufacturing sectors.
Table of Contents
1. Typical Uses & Selection Guidance
- Structural Applications
S550GD is widely used in structural framing, purlins, and heavy-duty roll-formed sections. Its excellent weldability and cold-forming properties allow for efficient processing in bending, cutting, stamping, and roll-forming operations.
- Corrosion Protection
When hot-dip galvanized or metallic-coated (Zinc, Zinc-Aluminium, Zinc-Iron, Zinc-Magnesium, or Aluminium-Zinc), S550GD provides reliable corrosion resistance for roofing, wall cladding, gutters, and general building applications, particularly in mild to moderate environments. The zinc coating offers a robust barrier against corrosion, extending the life of the steel.
- Forming Advantages
The higher yield strength of S550GD allows for easier bending, tighter radii, and reduced risk of cracking, making it ideal for complex profiles, detailed fabrication, and applications requiring superior formability.
S550GD is characterized by its excellent combination of high strength, sufficient ductility, and long-lasting corrosion protection. The very high minimum yield strength ensures a high load-bearing capacity under dynamic and static loads. The elongation at break of at least 10% ensures sufficient deformability to compensate for stresses in profiling and bending processes and to prevent cracking.
2. Technical Specifications Table
1. Chemical Composition Requirements (Maximum %)
| Steel Grade | Carbon (C) | Manganese (Mn) | Phosphorus (P) | Sulfur (S) | Silicon (Si) | Aluminum (Al) |
|---|---|---|---|---|---|---|
| S550GD | ≤ 0.20% | ≤ 1.70% | ≤ 0.10% | ≤ 0.045% | ≤ 0.60% | — |
2. Mechanical Property Requirements (Maximum Values)
| Steel Grade | Min. Yield Strength (MPa) | Min. Tensile Strength (MPa) | Min. Elongation (%) Lo=80mm | Bend Angle (°) | Mandrel Diameter (× Thickness t) |
|---|---|---|---|---|---|
| S550GD | ≥ 550 | 560–600 | ≥ 14 | 90 | 6t |
3. Coating Adhesion (180° Bend Test) Requirements
| Coating Class | Mandrel Diameter (× Thickness t) |
|---|---|
| Z100, Z200 | 1t |
| Z275, Z350, Z450, AZ150, AZ200, AM100, AM125, AM150, AM175, AM200, AM225 | 2t |
| Z600 | 3t |
4. Applicable Hot-Dip Metallic Coating Types
| Coating Class | Composition (%) | Key Features |
|---|---|---|
| Z (Zinc) | ≥99% Zinc | Basic corrosion protection; suitable for general use. |
| ZA (Zinc-Aluminium) | 95% Zn, 5% Al | Improved corrosion resistance over pure zinc. |
| ZF (Zinc-Iron) | Zinc with iron alloy | Enhanced hardness and wear resistance. |
| ZM (Zinc-Magnesium) | Zn with 2–4% Mg, 5–13% Al | Superior corrosion resistance in harsh environments. |
| AZ (Aluminium-Zinc) | 55% Al, 43.5% Zn, 1.5% Si | Excellent corrosion resistance and heat reflectivity. |
| AM (Aluminium-Magnesium) | Al with Mg alloy | High corrosion resistance; suitable for high-temperature applications. |
3. S550GD vs DX51D — What’s the Difference?
| Property | S550GD Steel Grade | DX51D Steel Grade |
|---|---|---|
| Yield Strength | ≥ 550 MPa | 270–500 MPa |
| Tensile Strength | 560–720 MPa | 270–500 MPa |
| Elongation (80mm) | ≥ 10% | ≥ 22% |
| Bendability | 180° with 6t mandrel | 180° with 6t mandrel |
S550GD Steel FAQ：
S550GD is a high-strength, hot-dip galvanized structural steel grade compliant with EN 10346. It provides a minimum yield strength of 550 MPa and combines excellent corrosion resistance, formability, and strength, making it ideal for construction, automotive, and industrial applications.
Key mechanical properties of S550GD include:
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Yield Strength: ≥ 550 MPa
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Tensile Strength: 560–720 MPa
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Elongation (80mm): ≥ 10%
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Bendability: 180° with 6t mandrel
S550GD is widely used in:
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Construction: Structural framing, roofing, and wall cladding
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Automotive: Reinforced vehicle parts and safety structures
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Industrial Fabrication: Machinery components and heavy-duty appliances
S550GD can be welded using standard methods such as arc, laser, or high-frequency induction welding. To ensure safety and weld quality, part of the zinc coating should be removed before welding to avoid harmful zinc vapors.
