What Is S550GD Galvanized Steel Coil
S550GD galvanized steel coil is a high-strength structural steel product with a hot-dip zinc coating, belonging to the EN 10346 standard series and designed for load-bearing applications requiring corrosion resistance. Common galvanized grades include S280GD, S350GD, S420GD, and S550GD. Among them, S550GD has the highest yield strength, making it ideal for construction, infrastructure, and heavy machinery manufacturing.
Key Applications
Building construction: roof panels, wall cladding, and steel framing, where the galvanized coating prevents rust in outdoor or humid environments. Infrastructure projects: highway guardrails, transmission towers, and bridge components, where high strength withstands heavy loads and harsh weather. Machinery manufacturing: agricultural equipment shells and construction machinery frames offering durability against mechanical wear. Automotive industry: truck body parts and trailer components where strength and corrosion resistance are critical.
Chemical Composition
Per EN 10346, carbon is 0.18 percent maximum, manganese 2.00 percent maximum, silicon 0.50 percent maximum, phosphorus 0.030 percent maximum, sulfur 0.025 percent maximum, and aluminum 0.020 percent minimum. The composition balances strength with weldability and toughness.
Mechanical Properties
Yield strength is 550 MPa minimum, tensile strength 600 to 730 MPa, elongation A80 of 12 percent minimum after galvanizing, and impact energy of 27 J minimum at minus 40 degrees C. A 180-degree bend test without cracking is required.
Standard Sizes and Price Factors
Thicknesses range from 0.8 to 12 mm with widths from 900 to 1800 mm, coil weights from 5 to 25 tons, and zinc coatings from 60 to 275 g per square meter. The price of S550GD depends on several factors: thickness, since thicker coils add cost; coating weight, since heavy-duty coatings above 200 g per square meter increase cost; order quantity, with bulk orders receiving discounts; and delivery time, with rush orders incurring a premium. Quotations should be requested with full specifications and destination terms to compare total landed cost including freight and customs.
Frequently Asked Questions
Q: What does S550GD mean?
S is structural steel, 550 is the minimum yield strength of 550 MPa, G is steel for cold forming or structural use per EN 10346, and D is hot-dip coating designation.
Q: What is the tensile strength of S550GD?
600 to 730 MPa with a minimum yield strength of 550 MPa and elongation of 12 percent minimum.
Q: What are the main applications?
Roof panels, wall cladding, highway guardrails, transmission towers, machinery shells, and truck components.
Q: What coating weights are available?
From 60 to 275 g per square meter depending on thickness and service environment.
Q: What drives the price of S550GD?
Thickness, coating weight, order quantity, delivery time, testing requirements, and delivery terms.
Q: Can S550GD be welded?
Yes, the controlled carbon content maintains weldability for structural fabrication.