In normal outdoor inland atmospheres (non‑coastal, low chloride, low industrial pollution), the atmospheric corrosion resistance of ASTM A606‑2 is essentially equivalent to that of other standard weathering steels such as ASTM A588 Grade B, Corten‑A, and most common Corten‑type weathering steels.
1. Compared with ASTM A588 Grade B
They share nearly identical alloy systems (Cu, Cr, Ni, Si) designed to form a dense, protective, stable patina.
Their long‑term corrosion rate, patina development speed, color evolution, and outdoor service life are very similar.
The only real difference is product form: A588 Gr.B is for thick structural plates and sections, while A606‑2 is for thin sheet and coil.
2. Compared with Corten‑A
Corten‑A is the traditional commercial weathering grade corresponding closely to A588 Gr.B.
In typical outdoor environments, A606‑2 performs equally well in terms of corrosion resistance and patina stability.
Both will reach a low, stable corrosion rate once the protective oxide layer is fully developed.
3. Compared with ASTM A606 Type 4 / Type 5
Type 4 and Type 5 have higher alloy contents (more Cr, Ni, Cu) and are intended for more severe environments (industrial, higher pollution, or moderate chloride exposure).
A606‑2 has standard corrosion resistance, which is lower than Type 4/5 but fully adequate for most architectural and landscape uses.
4. Compared with low‑strength weathering steels (e.g., SPA‑H, SPA‑C)
These grades also provide good atmospheric corrosion resistance.
In similar outdoor conditions, their corrosion performance is comparable to A606‑2.
The main difference is mechanical strength, not durability.
