Low carbon steel pipe known as mild steel pipe and carbon content from 0.10% to 0.30% in low-carbon steel is easy to accept all kinds of processing such as forging, welding and cutting, commonly used in the manufacturing chain, rivets, bolts, axis. The carbon content of less than 0.25% carbon steel, because of its low intensity, low hardness and soft, it is also known as mild steel pipes. It includes the majority of ordinary carbon steel pipe and part of high-quality carbon structural steel, mostly used in engineering structures without heat treatment, and some by carburizing and other heat treatment is used for wear-resistant mechanical parts.

Low carbon steel pipe annealed structure of ferrite and pearlite, the lower its strength and hardness, good ductility and toughness. Therefore, the cold good formability and can use methods such as crimping, bending, stamping, cold forming. This structural steel pipe has good weldability. Low carbon content of low carbon steel hardness is low, the poor machinability of normalizing treatment can improve machinability. Low-carbon steel pipes have a greater tendency of aging, both quench aging and the tendency to deformation aging tendencies. When the steel from high temperature and rapid cooling, the ferrite scratch carbon, nitrogen supersaturation at room temperature can slow the formation of iron carbonitride material, and thus improve the strength and hardness of the steel pipe, reduce the ductility and toughness of this phenomenon known as the quench aging. Low carbon steel quenching and air cooling will produce aging. Low-carbon steel large number of dislocations generated by deformation, the elastic interaction from the carbon and nitrogen atoms with dislocations in the ferrite, carbon, nitrogen atoms gather around the dislocations Line. This carbon, nitrogen atom and the dislocation line combination that old Coriolis air mass (Ke lop air mass). It will make the strength and hardness of the steel to improve the ductility and toughness decreased, a phenomenon known as the deformation aging. Deformation than the quench aging on the ductility and toughness of low carbon steel pipe greater harm evident in the tensile curve of the low-carbon steel and lower yield point.