How does WD-40 remove rust?
I'd say it works by coming out as a liquid. Then it diffuses through the porous rust layer or travels along the steel edge and expands to gas- as the mixture has a highly suppressed vaporisation point to push the rust from the inside. Steel has a high surface affinity for hydrocarbons as demonstrated by high difficult it is to clean. Partial vaporisation is plenty powerful enough to knock off rust.