Weathering Steel
The beauty of weathering steel is its rust. Alloyed with copper, phosphorus, chromium and nickel, it grows a dense, adherent patina that seals the surface — no flaking like ordinary steel. That gives two design paths: leave it uncoated and let the oxide be the finish, or thin down the protective coating and cut lifecycle maintenance.
| Grade | Thickness mm | Standard | Character |
|---|---|---|---|
| Q235NH | 8–80 | GB/T4171 | general weathering, weldable |
| Q295NH | 8–80 | GB/T4171 | slightly higher strength |
| Q355NH | 8–80 | GB/T4171 | common structural choice |
| Q415NH | 8–80 | GB/T4171 | higher strength, thinner design |
| Q460NH | 8–80 | GB/T4171 | towers and masts |
| Q500NH / Q550NH | 8–80 | GB/T4171 | heavy structures |
| Q265GNH–Q355GNH | 8–80 | GB/T4171 | high-corrosion class, facades |
| Q450NQR1 | ≤40 | railway ref. | classic wagon-body grade |
Typical applications
Ordering notes
The commonest mistake is treating weathering steel as "rust it however". Uncoated design assumes wet-dry cycling without standing water: the patina densifies over a few cycles; permanent soaking or heavy salt spray keeps it loose and scaly — near-coastal sites should think twice.
To speed stabilisation and avoid rust staining during construction, plates can be delivered with a stabilising treatment for an even facade colour. Weld with matching weathering consumables so the seam ages with the parent metal. Q450NQR1, the railway wagon classic, is a stock line for us.
常见问答
Does the rusting ever stop?
Effectively yes. In a suitable environment the patina densifies within one to three years and the corrosion rate drops very low. Evaluate the site first: standing water and heavy salt are disqualifiers for bare use.
GNH or NH?
GNH is the higher-corrosion-resistance family for exposed facades; NH balances strength and weldability for load-bearing structures. Facades take GNH; structures take NH.
Can the colour be controlled?
Yes — factory stabilising treatment brings the patina to a stable, even colour quickly and cleanly; natural weathering is free but patchy early on, needing site protection from runoff.
Further reading
A few related pieces worth a look: