What is Q355GNH weathering steel?
Q355GNH is weathering resistant steel, that is, atmospheric corrosion resistant steel, is a low alloy steel series between ordinary steel and stainless steel. This kind of steel is made of ordinary carbon steel by adding a small amount of corrosion resistant elements such as copper and nickel to improve its atmospheric corrosion resistance.
International Grade Equivalents
Q355GNH has widely recognized international equivalents, facilitating global sourcing and substitution:
- European Standard (EN 10025-5): Corresponds to S355J2WP (1.8946).
- US Standard (ASTM): Corresponds to A242 Type 1.
- Japanese Standard (JIS): Corresponds to SMA490W or SPA-H (similar properties).
Q355GNH weathering tempering chemical composition and mechanical properties
| Element | Content |
|---|---|
| Carbon (C) | ≤ 0.12% |
| Silicon (Si) | 0.20–0.75% |
| Manganese (Mn) | ≤ 1.00% |
| Phosphorus (P) | 0.07–0.15% |
| Sulfur (S) | ≤ 0.030% (tighter control ≤ 0.020 common) |
| Copper (Cu) | 0.25–0.55% |
| Nickel (Ni) | ≤ 0.65% |
| Chromium (Cr) | 0.30–1.25% |
| Molybdenum (Mo) | ≤ 0.30% |
| Ti / V / Nb | Micro-alloyed (Ti ≤ 0.10, V ≤ 0.12, Nb 0.015–0.060) |
| Property | Value |
|---|---|
| Yield strength | ≥ 355 MPa |
| Tensile strength | 490–630 MPa |
| Elongation | ≥ 19–22% (by thickness; confirm the edition) |
Q355GNH weathering steel characteristics and advantages
- Weather resistance: The weather resistance of Q355GNH is 2 to 8 times that of ordinary carbon steel, and it can maintain excellent corrosion resistance in harsh atmospheric environment for a long time.
- Coating property: Its coating property is 1.5 to 10 times that of ordinary carbon steel, which is easy to paint and further improve its corrosion resistance.
- Strength and toughness: Q355GNH has the strength and toughness of high-quality steel, and can withstand large external forces without deformation or fracture.
- Plastic ductility: The steel has good plastic ductility and is easy to be processed and formed in various shapes.
- Welding-cutting performance: excellent welding and cutting performance, can carry out a variety of welding and cutting operations, suitable for a variety of complex structural parts manufacturing.
Applications
- Railway vehicles: structural parts and components operating reliably in harsh environments.
- Bridge engineering: bridges under various weather conditions with greater load capacity and longer service life.
- Harbor construction: steel structural parts such as wharves and trestles.
- Oil production platforms: structural components exposed to marine atmospheres.
- Chemical and petroleum equipment: atmospheric-exposed structural parts and general process equipment (not for hydrogen-sulfide pressure vessels).
We maintain a stock of thousands of tons of steel, with same-day shipping for standard specifications. Small trial orders and samples are supported; minimum order quantities are not mandatory.
Supporting documents: Full set of original mill test certificates, CE certification, ISO quality report and SGS third-party inspection report attached with every container shipment, fully compliant with EU infrastructure tender material submission requirements
FAQ
Q: What does Q355GNH stand for?
A: Q = yield strength, 355 = minimum yield of 355 MPa, G = weathering (Gai), N = niobium-bearing, H = high-strength atmospheric corrosion resistant steel per GB/T 4171.
Q: How does Q355GNH resist corrosion?
A: The alloying elements (copper, chromium, nickel, phosphorus) promote a dense, adherent protective rust layer that blocks further atmospheric corrosion, unlike the loose rust of ordinary carbon steel.
Q: Is Q355GNH weldable?
A: Yes, with standard procedures; matching weathering-grade consumables are recommended for outdoor structures to preserve the corrosion-resistance properties.
Q: Can Q355GNH be used for hydrogen-sulfide containers?
A: No - it is an atmospheric weathering steel, not a sour-service pressure vessel steel; H2S service requires dedicated materials certified for that environment.
Company profile
Founded in 2008, Gnee (Tianjin) Supply Chain Group Co., Ltd. specializes in the global trade and processing of Corten steel products.
We handle all kinds of Corten engineering projects, such as bridges, gardens, hotels, and facade systems.
Compliant with ASTM, EN, and other international standards; third-party inspection supported.
Exported to over 200 countries and regions worldwide.
8 subsidiaries across China and overseas, ensuring global service coverage.
Application Fields: Architecture, landscaping, gardening, cladding, and urban infrastructure.
