For questions relating to corrosion/oxidation of steel frames, components, and other ferrous (iron-based) parts.
Rust is an iron oxide, a usually reddish-brown oxide formed by the reaction of iron and oxygen in the catalytic presence of water or air moisture.
Given sufficient time, any iron-based mass, in the presence of water and oxygen, could eventually convert entirely to rust. Surface rust is commonly flaky and friable, and provides no passive protection to the underlying iron, unlike the formation of patina on copper surfaces or aluminum oxide on aluminum surfaces. Rusting is the common term for corrosion of elemental iron and its alloys such as steel. Many other metals undergo similar corrosion, but the resulting oxides are not commonly called "rust."
