Q310GNH Weathering Steel
Q310GNH is a Chinese standard weathering steel (GB/T 4171) with enhanced phosphorus content for improved atmospheric corrosion resistance. It offers higher strength than Q265GNH while maintaining good formability and weldability, making it suitable for railway rolling stock, containers, and structural applications.
Chemical Composition (heat analysis, %)
| Grade | C | Si | Mn | P | S | Cu | Cr | Ni | Others* |
|---|---|---|---|---|---|---|---|---|---|
| Q310GNH | ≤0.12 | 0.25–0.75 | 0.20–0.50 | 0.07–0.12 | ≤0.020 | 0.20–0.45 | 0.30–1.25 | ≤0.65 | 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 | |||
| Q310GNH | 310 | — | — | — | ≥450 | 26 | — | — | — | a | — | — | ||
| 310 = Yield strength (MPa) for ≤16mm only — = not applicable for other thicknesses ≥450 = Tensile strength (min) (MPa) a = Bending mandrel diameter for ≤6mm only (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
Q310GNH features enhanced phosphorus content for improved atmospheric corrosion resistance. It forms a dense protective patina, eliminating the need for painting in many environments. With higher strength than Q265GNH, it is suitable for:
Available thickness: typically ≤16mm. Mill test certificates (EN 10204 3.1) supplied.
© Q310GNH technical data sheet — Based on GB/T 4171:2008 & amendments. Always verify with mill certificate.