Wrought iron

Genuine wrought iron has not been made commercially since the 1970s: nearly carbon-free iron with fibrous slag stringers rolled through it, which give it a woody grain and remarkable corrosion resistance. Almost everything sold today as "wrought iron" gates is mild steel, bent cold. The real material is worth knowing about because Victorian ironwork survives outdoors far better than modern steel does — the slag fibres blunt the progress of rust.

Properties

Density

7,700 kg/m³ (7,600–7,800) — 7.70 g/cm³

Melting range

1500–1540 °C

Tensile strength

250–400 MPa

Young's modulus

190 GPa

Thermal conductivity

59 W/(m·K)

Thermal expansion

12 µm/(m·K)

Floats in water

No

Magnetic

Yes

What it is used for

• Victorian gates, railings and chain
• Historic bridges and roof trusses
• Blacksmithing and restoration work
• Anchor chain and rigging (historically)

How it compares

Does it rust?

Yes, and readily. Rust is iron oxide, and it is flaky rather than adherent — it does not seal the surface, so oxygen and water keep reaching fresh metal underneath and the process continues until the section is gone. That non-protective quality is what makes rust different from the oxide layers on other metals.

Is it magnetic?

Iron, nickel and cobalt are the three common ferromagnetic elements, and anything based mostly on them is strongly attracted to a magnet.