The low carbon steel is a kind of carbon steel with less than 0.25% carbon content, which is also called mild steel because of its low strength, low hardness and softness. It includes most common carbon structural steels and a portion of carbon structural steels with high quality. Most of them are used in engineering structures without heat treatment, and some are used by carburizing and other heat treatment for mechanical parts that require wear resistance.
The annealed microstructure of low carbon steel is ferrite and a little pearlite with lower strength and hardness and better plasticity and toughness. Therefore, its property of cold forming is good, and cold forming can be carried out by crimping, bending, stamping and so on. This kind of steel also has good weldability. The low carbon steel with a carbon content ranging from 0.10% to 0.30% is easily subject to various processes such as forging, welding and cutting, and is often used in the manufacture of chains, rivets, bolts, shafts, etc.
Categories of low carbon steel
The low carbon steel
is generally rolled into angle steels, channel steels, I-beams, steel pipes, steel strips or steel plates and can be used in the manufacture of various building components, containers, boxes, furnaces and agricultural machinery, etc. The low carbon steel with high quality can be rolled into thin plates to make car cabs, engine hoods and other deep-drawn products. It can also be rolled into bars to make mechanical parts with low requirements of strength. The low carbon steel generally does not undergo heat treatment before use, while with a carbon content of 0.15 % or more, it needs carburizing or cyanidation treatment and is used for shaft, shaft sleeve, sprocket and other parts which require high surface temperature and good wear resistance.
The use of low carbon steel is limited because of its low strength, while its strength can be greatly improved by increasing the manganese content in carbon steel and adding some alloying elements such as vanadium, titanium and niobium. If the carbon content in the steel is reduced and a small amount of aluminum, a small amount of boron and carbide former are added to the steel, the ultra-low carbon bainite group can be obtained with high strength and good ductility and toughness.