Slab: the ratio of section width and height is large, mainly used for rolling plate. Billet: cross section width, height equal, or little difference, mainly used for rolling steel, wire. Continuous cast steel billets and rectangular billets are mainly represented by plain carbon steel, low carbon and low silicon cold rolled material, high quality carbon structural steel, low alloy high strength steel and special steel grades. Billet is steel, after processing can be used to do mechanical parts, forging, processing all kinds of steel, steel Q345B channel steel, wire is the role of billet