When iron is smelted from its ore by commercial processes, it contains more carbon than is desirable. To become steel, it must be melted and reprocessed to reduce the carbon to the correct amount, at which point other elements can be added. This liquid is then continuously cast into long slabs or cast into ingots. Approximately 96% of steel is continuously cast, while only 4% is produced as ingots.
The ingots are then heated in a soaking pit and hot rolled into slabs, blooms, or billets. Slabs are hot or cold rolled into sheet metal or plates. Billets are hot or cold rolled into bars, rods, and wire. Blooms are hot or cold rolled into structural steel, such as I-beams and rails. In modern steel mills these processes often occur in one assembly line, with ore coming in and finished steel coming out. Sometimes after a steel’s final rolling it is heat treated for strength, however this is relatively rare.