Q355GNH high weathering steel plate is a high-strength, atmospheric corrosion-resistant structural steel produced in accordance with GB/T standards. It is specifically designed for long-term outdoor exposure, offering excellent resistance to atmospheric corrosion combined with reliable mechanical strength.
Q355GNH is widely used in bridges, railway engineering, steel structures, and other infrastructure projects where durability and low maintenance are required.
What Is Q355GNH Steel?
The designation Q355GNH can be interpreted as follows:
- Q – Yield-strength-based structural steel
- 355 – Minimum yield strength of 355 MPa
- G – Structural steel for engineering applications (such as bridges)
- N – Supplied in normalized or TMCP condition
- H – High weathering (atmospheric corrosion-resistant) steel
Q355GNH belongs to the family of high weathering steels, providing stronger corrosion resistance than ordinary weathering grades.
Chemical Composition of Q355GNH (Typical, wt.%)
The superior weathering performance of Q355GNH comes from its optimized alloying design.
| Element | Typical Content |
|---|---|
| Carbon (C) | ≤ 0.16 |
| Silicon (Si) | ≤ 0.55 |
| Manganese (Mn) | ≤ 1.60 |
| Phosphorus (P) | ≤ 0.035 |
| Sulfur (S) | ≤ 0.030 |
| Copper (Cu) | 0.25 – 0.55 |
| Chromium (Cr) | 0.40 – 1.30 |
| Nickel (Ni) | ≤ 0.65 |
| Vanadium / Niobium (V / Nb) | Micro-alloyed (if required) |
Key Point:
The combined effect of Cu, Cr, and Ni promotes the formation of a dense and stable oxide layer, significantly slowing corrosion in atmospheric environments.
Strength and Mechanical Properties of Q355GNH
Q355GNH offers an excellent balance of strength, toughness, and ductility.
Typical Mechanical Properties
| Property | Value |
|---|---|
| Yield Strength | ≥ 355 MPa |
| Tensile Strength | 470 – 630 MPa |
| Elongation | ≥ 20% |
| Impact Toughness | Qualified (according to specified temperature grade) |
The normalized or TMCP delivery condition ensures uniform microstructure and stable performance, even in large-thickness plates.
Atmospheric Corrosion Resistance
Compared with ordinary structural steel, Q355GNH provides:
- 2–8 times higher atmospheric corrosion resistance
- Slower rust penetration rate
- Reduced section loss over long service periods
- Extended service life in urban, industrial, and coastal environments
This makes Q355GNH especially suitable for unpainted or lightly coated steel structures.
Fabrication Performance
Q355GNH high weathering steel plate demonstrates good processing characteristics:
- Excellent weldability with matching weathering steel consumables
- Suitable for flame, plasma, and laser cutting
- Good cold bending and forming performance
Proper welding procedures help maintain corrosion resistance in welded joints.
Typical Applications
Due to its chemical and strength properties, Q355GNH is widely used in:
- Bridge structures and girders
- Railway engineering and rolling stock
- Steel towers and transmission structures
- Industrial outdoor frameworks
Large-scale infrastructure exposed to harsh environments
Conclusion
Q355GNH high weathering steel plate combines optimized chemical composition with reliable mechanical strength, offering excellent atmospheric corrosion resistance and long service life. Its superior performance makes it an ideal material for demanding outdoor structural applications.
For stable supply, full certification, and professional technical support of Q355GNH weathering steel plate, GNEE Steel is your trusted partner.
If you want to learn more about GNEE's products, you can send an email to alloy@gneesteelgroup.com. We are more than happy to assist you.
Q: What is the impact toughness of Q355NHB?
A: Q355NHB has a longitudinal impact energy of ≥47 J at 20℃, and optional low-temperature impact testing allows its use in cold regions.
Q: How good is the corrosion resistance of Q355NHB?
A: Q355NHB has excellent atmospheric corrosion resistance, with a corrosion rate of 0.02-0.04 mm/year in industrial atmospheric environments.
Q: Does the performance of Q355NHB change with plate thickness?
A: Yes, the yield strength and elongation of Q355NHB slightly decrease as the plate thickness increases, while tensile strength remains stable.
Q: What chemical elements make Q355NHB have weather resistance?
A: The weather resistance of Q355NHB comes from corrosion-resistant elements such as Cu, Cr, and Ni added to its composition.
Q: What are the common delivery states of Q355NHB?
A: Common delivery states of Q355NHB include hot-rolled, controlled rolling, normalized, and customized states like quenched-tempered.
Q: What thickness, width, and length specifications of Q355NHB are available?
A: Q355NHB has common thicknesses from 10mm to 40mm, with various width and length options, and non-standard sizes can be customized.
