What Is Q550NH Weathering Steel Coil?
Q550NH weathering steel coil is produced according to GB/T 4171 for atmospheric corrosion-resistant structural steel. Compared with supplying every component as an individual plate, coil form is particularly useful when manufacturers require repeated dimensions, continuous production or large quantities of relatively thin weathering steel parts.
After decoiling and leveling, Q550NH steel coil can be processed into Q550NH steel sheet or cut-to-length plate according to the required dimensions. It can then undergo cutting, bending, welding, drilling and other fabrication processes.
Q550NH Steel Coil Specification
The basic technical requirements of GB/T 4171 Q550NH weathering steel are shown below.
| Item | Specification |
|---|---|
| Grade | Q550NH |
| Standard | GB/T 4171 |
| Product Form | Hot Rolled Coil |
| Production Route | Hot Rolled |
| Standard Plate & Strip Thickness | ≤60 mm |
| Min. Yield Strength | 530–550 MPa, depending on thickness |
| Tensile Strength | 620–780 MPa |
| Main Processing | Slitting, Leveling, Cut-to-Length, Cutting, Bending |
GB/T 4171 specifies Q550NH plate and strip up to 60 mm, but this does not mean that every steel mill can produce a 60 mm Q550NH coil. Actual coil thickness, width, inner diameter, outer diameter and single-coil weight depend on rolling mill capability and should be confirmed before ordering.
Chemical Composition of Q550NH Weather Resistant Steel Coil
Unlike ordinary structural carbon steel, Q550NH Corrosion Resistant Steel contains Cu, Cr and Ni as important weathering alloy elements.
| Element | Content |
|---|---|
| C | ≤0.16 |
| Si | ≤0.65 |
| Mn | ≤2.00 |
| P | ≤0.025 |
| S | ≤0.030 |
| Cu | 0.20–0.55 |
| Cr | 0.30–1.25 |
| Ni | 0.12–0.65 |
Microalloying elements including Nb, V and Ti may also be used for property control. Under the standard requirements, Nb can be 0.015–0.060%, V 0.02–0.12% and Ti 0.02–0.10%, while the combined addition of Nb + V + Ti should not exceed 0.22%.
The Cu-Cr-Ni alloy system helps the steel develop a more stable corrosion layer under suitable atmospheric wet-dry cycling conditions. The actual weathering performance still depends on humidity, chloride exposure, drainage and the specific service environment.
Mechanical Properties of Q550NH Steel Coil
The yield strength of Q550NH steel coil and Q550NH steel sheet should be checked according to material thickness rather than simply describing all Q550NH material as "550 MPa yield strength."
| Thickness | Min. Yield Strength | Tensile Strength | Min. Elongation |
|---|---|---|---|
| t ≤16 mm | 550 MPa | 620–780 MPa | 16% |
| 16 < t ≤40 mm | 540 MPa | 620–780 MPa | 16% |
| 40 < t ≤60 mm | 530 MPa | 620–780 MPa | 15% |
For most relatively thin coil applications, the first thickness range is particularly relevant, but the actual ordered thickness and corresponding MTC values should always be checked.
Processing of Q550NH Weathering Steel Coil
For coil users, downstream processing capability is an important part of procurement. Q550NH steel coil can be decoiled, leveled and cut into customer-specified Q550NH steel sheet sizes. The material can also be slit into narrower strips for continuous fabrication.
After leveling or cut-to-length processing, additional fabrication can include CNC cutting, laser or plasma cutting where appropriate, bending, drilling, beveling and welding preparation.
For exposed architectural or weathering applications, surface preparation such as shot blasting or controlled pre-weathering can be considered after component fabrication when required by the project.
Applications of Q550NH Weather Resistant Steel Coil
Because Q550NH combines relatively high yield strength with atmospheric corrosion resistance, it can be used for fabricated products that require both structural performance and outdoor durability.
Typical applications include transportation equipment, railway components, vehicle structural parts, containers, bridge-related components, towers, outdoor equipment housings and other welded weather-resistant structures.
GB/T 4171 identifies vehicles, bridges, containers, buildings and other structural applications among the intended uses of NH-series weathering steels.
What Information Is Needed When Ordering Q550NH Steel Coil?
For an accurate Q550NH steel coil quotation, buyers should identify the grade and standard together with the required thickness, coil width, quantity, and destination.
For coil orders, it is also useful to specify the required coil weight, coil inner diameter, edge condition, whether slitting or leveling is required, final sheet size if cut-to-length processing is needed, and inspection certificate requirements.
Q550NH Steel Coil Supply and Processing
Gnee supplies GB/T 4171 Q550NH weather-resistant steel coil, Q550NH weathering steel coil, Q550NH steel sheet, and Q550NH steel plate for structural and fabrication projects. Coil material can be supplied with slitting, leveling, cut-to-length, cutting, bending, and other processing according to project requirements.
Get Q550NH Steel Coil Price & Sample MTC
Send us your required Q550NH steel coil thickness, width, coil weight, quantity, processing requirements, and destination port. We can check the appropriate supply specifications and provide a quotation, lead time, and sample MTC for technical review.
