Black steel is created through a mill process which involves rolling the steel at a high temperature (typically at a temperature over 1700° F), which is above the steel’s recrystallization temperature. When steel is above the recrystallization temperature, it can be shaped and formed easily, and the steel can be made in much larger sizes.
Bright drawn steel is essentially black steel that has had further processing. The steel is processed further in cold reduction mills, where the material is cooled (at room temperature) followed by annealing and/or tempers rolling.
The raw material used in the bright bar manufacturing process are called ‘black bars’ – steel wire rods that are mostly in coil form. They are cleaned by removing their scales, which is done either by ‘pickling’ (acid cleansing) or ‘shot blasting’ (blasting steel balls) techniques. Once cleaned, the curvy coil is opened, straightened and fed into the Combined Wire Drawing machine. In the drawing machine, the wire rods are reduced (‘drawn’) to a smaller diameter, straightened and polished/cut to required specifics. The resultant finished product is a Bright Bar (called ‘bright’ due to its shiny finish), also called a Cold Drawn Bar.