Generally, sheet metal will rust in 2-3 years, mainly because sheet metal is ordinary steel plate. The following are related introductions: 1, thin iron plate: the automobile shell is made of thin iron plate, which has been fully rusted before leaving the factory and has not been smashed and welded, so the metal plate can be made, but it cannot be welded. Once welded, it will destroy the rust-proof layer. The slope is damaged and will not rust. Cars used in coastal areas will rot in two or three years. 2. automotive sheet metal: It is equal to automotive sheet metal repair, which means that the car body should be repaired after the collision, that is, all the work except the painting work of car body anticorrosion and decoration.