Common metals that don’t rust include:

• Aluminum
• Stainless Steel (some grades)
• Galvanized Steel

Aluminum

Aluminum corrodes but it does not rust. Rust refers only to iron and steel corrosion. Aluminum is actually very prone to corrosion. However, aluminum corrosion is aluminum oxide, a very hard material that actually protects the aluminum from further corrosion.

Stainless Steels

Stainless steel doesn’t rust because it is an alloy that contains the metals chromium and nickel. Chromium must comprise at least 10 percent of the steel alloy for stainless steel to be rust resistant.

Galvanized Steel

Although galvanizing will inhibit attack of the underlying steel, rusting will be inevitable after some decades of exposure to weather, especially if exposed to acidic conditions. For example, corrugated iron sheet roofing will start to degrade within a few years despite the protective action of the zinc coating.

These Metals Don’t Rust But…

While these metals don’t rust, that does not mean that they do not corrode. They have their own forms of corrosion, such as pitting that can occur in stainless steel or the blue-green tarnish found on oxidized copper. Furthermore, if they are brought into contact with a carbon steel or other type of steel that does rust, iron deposits can be made on the surface of these materials that will oxidize and create rust.