Building steel: Building steel can generally be divided into steel for steel structures and steel bars for reinforced concrete structures. Steel structure steel mainly includes ordinary carbon structural steel and low-alloy structural steel. The varieties are section steel, steel pipe and steel bar. There are angle steel, I-beam and channel steel in section steel. Steel bars for reinforced concrete structures can be divided into: hot-rolled steel bars, heat-treated steel bars, cold-drawn steel bars, cold-drawn low-carbon steel wires and steel stranded pipes according to the processing methods; according to the surface shape, they can be divided into smooth steel bars and threads; according to steel varieties It can be divided into low carbon steel, medium carbon steel, high carbon steel and alloy steel.