Q295GNH Weathering Steel
Q295GNH is a Chinese standard weathering steel (GB/T 4171) with enhanced phosphorus content for improved atmospheric corrosion resistance. It is widely used in railway rolling stock, containers, bridges, and structural applications requiring good weldability and formability.
Chemical Composition (heat analysis, %)
| Grade | C | Si | Mn | P | S | Cu | Cr | Ni | Others* |
|---|---|---|---|---|---|---|---|---|---|
| Q295GNH | ≤0.12 | 0.10–0.40 | 0.20–0.50 | 0.07–0.12 | ≤0.020 | 0.20–0.45 | 0.30–0.65 | 0.25–0.50 | ①,② |
📌 Notes on chemical composition:
- ① Micro-alloying: may contain Nb (0.015–0.060%), V (0.02–0.12%), Ti (0.02–0.10%), Alt ≥0.020%. At least one element meets lower limit; total Nb+V+Ti ≤0.22%.
- ② Optional: Mo ≤0.30%, Zr ≤0.15% may be added by agreement.
- ③ Permissible deviations for product analysis according to GB/T 222. Sulphur can be agreed ≤0.008%.
- ④ Through negotiation, Ni lower limit may be waived, or C ≤0.15% upon request.
- ⑤ Smelting: converter or electric furnace, fully killed steel. Delivery states: hot-rolled / controlled-rolled / normalized.
Mechanical Properties & Bending Test
| Grade | Lower yield strength ReL (≥ MPa) | Tensile strength Rm (MPa) | Elongation after fracture A/% ≥ | 180° Bending mandrel diameter |
||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| ≤16 | >16-40 | >40-60 | >60 | N/mm² | ≤16 | >16-40 | >40-60 | >60 | ≤6 | >6-16 | >16 | |||
| Q295GNH | 295 | 285 | — | — | 430 – 560 | 24 | 24 | — | — | a | 2a | 3a | ||
| 295/285 = Yield strength by thickness (MPa) — = not applicable for >40mm 430-560 = Tensile strength range (MPa) a/2a/3a = Bending mandrel diameter (a = specimen thickness) | ||||||||||||||
Note: 'a' = specimen thickness. Rp0.2 applies if no yield plateau. Bending specimen width b=35mm for arbitration. "—" indicates the property is not specified for that thickness range.
Smelting & Delivery Conditions
- 🔹 7.1.2 – Permissible deviations for product analysis per GB/T 222.
- 🔹 7.2 – Steelmaking: converter or electric furnace, fully killed. Method at supplier's option unless specified.
- 🔹 7.3 – Delivery: hot-rolled, controlled-rolled, or normalized condition. Cold-rolled sheets generally delivered in annealed condition.
- 🔹 Fabrication: Excellent weldability and cold forming. Preheating (100–150°C) recommended for thickness >25 mm.
🌉 Typical Applications & Properties
Q295GNH features enhanced phosphorus content for improved atmospheric corrosion resistance. It forms a dense protective patina, eliminating the need for painting in many environments. Commonly used in:
Available thickness: 2mm to 40mm (typical). Mill test certificates (EN 10204 3.1) supplied.
© Q295GNH technical data sheet — Based on GB/T 4171:2008 & amendments. Always verify with mill certificate.