Steel sheets used for automobile bodies are mostly carbon steels (carbon-ferrous alloy) because of the stamping requirements and resistance to severe usage conditions that vehicles must endure.

Depending upon the steel’s carbon content, technical properties of the metal are changed. Higher the carbon content increases impact resistance, but the formability and weldability are reduced. Even panel repair would be difficult. For these reasons most body parts are made from low carbon steels, with a carbon content of 0.1 to 0.4% or less.

Recently, more high-strength steel has been used. Though much thinner than conventional soft steel, it provides the same level of strength. High-strength steel sheet has a higher tensile strength, 340 MPa or higher, and a higher yield point. This makes it possible to reduce the total weight of a body, while maintaining collision safety.

Where required, zinc-plated sheets are used to improve corrosion resistance.

Body component parts have different section requirements. Because most are press formed from a thin steel sheet, different rigidities are specified, depending upon where strength is needed, by adding different thicknesses or reinforcements.