Rolling mill. Roll of red-hot sheet steel glowing in the rolling mill of a steel foundry. Rolling consists of taking red-hot steel from a furnace and passing it through a series of rollers. The metal is rolled to produce the required shape for sale. A variety of shapes, including sheets, rods and pipes, can be made in this way. This working of the steel also improves its quality by toughening the metal and refining its crystal structure.