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Product Overview
Our 1.2mm by 1250mm galvalume steel coil in G550 grade delivers the strength and durability that structural applications demand. At 1.2mm gauge and 1250mm width, this coil hits the sweet spot for load-bearing profiles, framing systems, and industrial fabrications where standard commercial grades lack the mechanical backbone. G550 is a high-strength structural grade that trades some forming ease for significantly elevated yield and tensile strength, making it the go-to specification for purlins, girts, decking, and engineered building components.
This is not light-gauge cladding material. This is structural steel with a protective aluminum-zinc alloy skin, ready to carry loads and withstand the elements.
Understanding G550
G550 refers to the minimum yield strength of 550 MPa — more than double the strength of DX51D commercial quality. The "G" prefix denotes structural grade per Australian/New Zealand standard AS 1397, with equivalent grades including S550GD+AZ per EN 10346 and Grade 80 per ASTM A792. The high strength comes from controlled carbon and manganese additions in the base steel, combined with thermomechanical processing that develops a fine, strong grain structure.
The trade-off is reduced ductility. G550 elongation typically runs 2% to 8% depending on exact chemistry and processing, compared to 28% or more for DX51D. This means G550 is not suited for deep drawing or tight-radius bending. It is engineered for roll-forming into open sections, press-braking into angles and channels, and flat applications where strength governs design.
Specifications
| Product Name | 1.2X1250MM Galvalume Steel Coil Sheet G550 |
| Grade | G550 per AS 1397. Equivalent to S550GD+AZ per EN 10346, Grade 80 per ASTM A792. |
| Yield Strength | Minimum 550 MPa |
| Tensile Strength | Minimum 550 MPa, typically 550–700 MPa range |
| Elongation | 2% to 8% in 80mm gauge length, depending on thickness and exact specification |
| Coating Mass | AZ150 standard for structural applications. AZ100, AZ120, AZ180, and AZ200 available. Heavier coatings recommended for coastal or industrial exposures |
| Thickness | 1.2mm primary specification. Full range 0.4mm to 2.0mm available |
| Width | 1250mm primary specification. Standard widths also include 914mm, 1000mm, and 1219mm. Slitting to custom widths from 40mm |
| Coil Inner Diameter | 508mm or 610mm |
| Coil Weight | 5–10 metric tons standard |
| Surface Finish | Minimized spangle or zero spangle for clean appearance and consistent paint adhesion |
Why 1.2mm x 1250mm?
This dimension pairing is purpose-built for efficiency in structural roll-forming and profiling operations. At 1.2mm, the material provides the section modulus and stiffness needed for medium-span purlins, girts, and decking profiles without excessive weight. The 1250mm width optimizes nesting for common profile geometries and minimizes edge trim waste when slit to standard purlin widths.
For building systems manufacturers, this is a production-ready format that feeds directly into roll-forming lines, brake presses, and automated punching stations.
Manufacturing Process
Production starts with high-strength hot-rolled substrate selected for controlled chemistry and clean inclusion content. The strip is cold-rolled to 1.2mm gauge with tight thickness tolerance, then continuous-annealed under precisely controlled thermal cycles that develop the G550 strength level while maintaining enough ductility for roll-forming without edge cracking.
The annealed strip enters the hot-dip Al-Zn bath at approximately 600°C. A gas knife system controls coating mass to the specified AZ value. Controlled cooling locks in the coating microstructure. A light skin pass improves surface finish and flatness, followed by tension leveling to eliminate coil set. Optional chemical treatment and oiling complete the process.
Applications
Building & Construction: Purlins and girts for pre-engineered metal buildings, structural decking for concrete slabs, roof and wall framing, door and window lintels, and mezzanine floor joists.
Infrastructure: Bridge decking, highway guardrails, noise barrier posts, lighting pole sections, and sign structure supports.
Industrial: Conveyor frame sections, racking uprights and beams, platform grating supports, machinery guards, and material handling equipment.
Agriculture: Grain storage bin rings, animal confinement building frames, equipment shelters, and greenhouse structures.
Transportation: Trailer chassis components, container corner posts, and vehicle body structural reinforcements.
Packaging & Export
Coils are protected for ocean transit with waterproof kraft paper, VCI anti-corrosion film, galvanized steel outer covers, steel edge guards, and circumferential strapping. Each package is labeled with grade, coating mass, dimensions, heat number, and handling instructions.
We ship FOB, CFR, CIF, DAP, or DDP from Tianjin, Shanghai, or Qingdao. Container loads of 25–27 tons optimize freight costs.
FAQ
Q: What is G550?
A: High-strength structural grade with 550 MPa minimum yield. Much stronger than DX51D but less formable. For load-bearing sections, not deep drawing.
Q: Can I bend G550 tight?
A: Not recommended. Keep bend radius at 3x thickness minimum. Use roll-forming for best results.
Q: Is AZ150 enough for structural?
A: Yes for most inland and mild industrial environments. Use AZ200 for coastal or heavy pollution. Bare AZ150 G550 roofs last 25+ years in moderate climates.
Q: Diff between G550 and G300?
A: G550 is nearly double the strength. G300 forms easier but needs thicker sections for same load. G550 saves weight and steel cost in structural designs.
Q: Can G550 be welded?
A: Yes. Use standard MIG or stick welding with appropriate filler metal. Protect coating near weld zone with touch-up paint to prevent rust.
Q: MOQ?
A: 1 tons per size for mill production. Stocked sizes from 5 tons.
Q: Payment?
A: 30% TT deposit + 70% against B/L copy. L/C at sight for large orders.
Q: Samples?
A: Yes. Small coil samples or test coupons free. Courier on buyer.
Q: How can I get your quotation as soon as possible?
A:Please contact:
Email:[email protected]
WeChat/WhatsApp/Mobile: +8613512028034
