G550 Steel Grades
High-Strength Galvanized Steel for Structural and Industrial Applications
- Technical Support
G550 Steel Technical Specifications & Applications
G550 is a high-strength, hot-dip galvanized structural steel grade compliant with the Australian AS 1397 standard, characterized by a minimum yield strength of 550 MPa. This steel grade offers an optimal balance of strength, formability, and corrosion resistance, making it suitable for various applications in construction and manufacturing.
G550 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, G550 meets international standards, ensuring reliable performance in galvanized and structural steel applications. As a core product of Hengze Steel Group, G550 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
G550 is a high-strength, hot-dip galvanized steel grade produced to the Australian AS 1397 standard, designed for demanding structural and cold-forming applications. With a minimum yield strength of 550 MPa, it offers an excellent balance of strength, formability, and corrosion resistance. G550 is commonly used in structural framing, purlins, and heavy-duty roll-formed sections. Its superior weldability and cold-forming properties enable efficient bending, cutting, stamping, and roll-forming operations. Manufactured under strict quality control, G550 ensures consistent performance for construction and industrial applications.
- Corrosion Protection
G550 features a durable aluminum-zinc (AZ) coating with approximately 55% aluminum, 43.5% zinc, and 1.5% silicon. This coating provides long-term protection against rust and oxidation, even in harsh industrial or outdoor environments, while maintaining a smooth surface finish suitable for painting or further processing. The aluminum-zinc alloy also enhances heat resistance, making G550 suitable for high-temperature applications.
- Forming Advantages
G550 offers excellent formability with elongation ≥30% and minimal springback, ideal for producing complex shapes with high dimensional accuracy. Rigorous production standards ensure uniform mechanical properties, compliance with international specifications, and reliable performance in structural and engineering applications.
2. Technical Specifications Table
1. Chemical Composition Requirements (Maximum %)
| Steel Grade | Carbon (C) | Silicon (Si) | Manganese (Mn) | Phosphorus (P) | Sulfur (S) | Titanium (Ti) |
|---|---|---|---|---|---|---|
| G550 | ≤ 0.20% | ≤ 0.02% | ≤ 1.20% | ≤ 0.04% | ≤ 0.03% | Not specified |
2. Mechanical Property Requirements (Maximum Values)
| Steel Grade | Min. Yield Strength (MPa) | Min. Tensile Strength (MPa) | Min. Elongation (%) Lo=80 mm | Bend Angle (°) | Mandrel Diameter (× Thickness t) |
|---|---|---|---|---|---|
| G550 | 550 | 550 | ≥ 2% | 180° | 4t |
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. G550 vs S220GD — What’s the Difference?
| Property | G550 Steel Grade | S220GD Steel Grade |
|---|---|---|
| Yield Strength | ≥550 MPa | ≥220 MPa |
| Tensile Strength | ≥550 MPa | 300–440 MPa |
| Elongation (80 mm) | ≥2% | ≥20% |
| Bendability | 180° with 4t mandrel | 180° with 6t mandrel |
G550 Steel FAQ：
G550 steel is a high-strength, hot-dip galvanized structural steel grade compliant with the Australian AS 1397:2021 standard. With a minimum yield strength of 550 MPa, it offers excellent strength, corrosion resistance, and durability, making it ideal for construction, industrial, and manufacturing applications.
G550 steel is widely used in:
Roofing and cladding
Structural framing and purlins
Heavy-duty roll-formed sections
Fencing posts and rails
Automotive components
Household appliances
Its high strength and corrosion resistance make it suitable for both industrial and structural applications.
G550 steel is available with various metallic coatings to enhance corrosion resistance:
Zinc (Z)
Zinc/iron alloy (ZF)
Zinc/aluminum (ZA)
Zinc/aluminum/magnesium (ZM)
Aluminum/zinc (AZ)
Aluminum/zinc/magnesium (AM)
These coatings ensure long-term protection in both indoor and outdoor environments.
Yield Strength: ≥550 MPa
Tensile Strength: ≥550 MPa
Elongation (Lo=80 mm): ≥2%
Bendability: 180° with 4t mandrel
These properties provide high durability while maintaining formability for cold-forming and roll-forming processes.
G550 offers superior strength and corrosion resistance compared to lower-strength grades such as S220GD. Its higher yield and tensile strength make it more suitable for demanding structural, industrial, and high-load applications.
