Bake-hardened steel is a type of steel that gains its strength and hardness through a combination of carbon and nitrogen atoms, along with the addition of strengthening elements such as phosphorus and manganese. These elements form solid solutions within the steel that prevent the movement of dislocations, leading to increased strength and hardness.

Once the steel has been shaped, it undergoes age hardening, which involves heating it to a specific temperature and holding it there for a certain duration. This process allows for the precipitation of small particles in the steel, further enhancing its strength.

Bake-hardened steel is commonly used in applications that require high durability and strength, such as automotive outer coverings. The steel typically has a ferrite microstructure, which is soft and ductile but can be hardened through the addition of other elements and heat treatment. However, excessive carbon can make the steel brittle and reduce its overall strength.