Does cast iron rust?
Yes it does rust.
Ductile iron has better corrosion resistance than gray cast iron. Some alloy cast iron has better corrosion reisistance. However, any cast iron will rust without any surface treatment.
There are many types of surface treatments that can pretect iron castings from rust, such as primer painting, surface painting, electophoretic coating and zink galvanizing etc. As for the detailed information about surface coatings of metal castings, please refer to the links below "Surface Coating of Iron Castings ".
Rust is the oxidation of the cast iron. Oxygen in the air combines with the base metal to create the rust. The rust protects the metal underneath. Cast iron is not "reacting" to rust. It is participating in FORMING the rust. ************** previous answer below *************** Very well as the rust actually protects the base metal
Cast iron is much heavier than cast aluminum. A magnet or compass needle will be attracted to cast iron, but will not be attracted to cast aluminum. Cast iron quickly develops a dark coating of iron oxide (rust) after being exposed to humid (damp) air and will continue to rust if left exposed, while cast aluminum becomes coated with an amost invisible whitish layer of aluminum oxide that protects it fom further oxidization. Cast iron…