The characteristics of the mild carbon steel pipe

Mild carbon steel pipe annealing organization ferrite and a small amount of pearlite, lower its strength and hardness, good ductility and toughness. Therefore, the cold formability of good can be curling, bending, stamping and other methods of cold forming. This steel has good weldability. The hardness of mild carbon steel with a low carbon content is low, and poor machinability, the normalizing treatment can improve its machinability.

The aging tendency of mild carbon steel, both quench aging tendency deformation aging tendency. When the rapid cooling of the steel from high temperature ferrite scraping carbon, nitrogen supersaturated at ordinary temperature, it can also be slowly formed a carbonitride of iron, hot dip galvanized steel and thus the strength of steel and the hardness is increased, and the ductility and toughness decrease this phenomenon is called quench aging. Low carbon steel quenching and air cooling will produce aging. The low carbon steel by deformation to produce a large amount of dislocations, from carbon and nitrogen atoms in the ferrite, and dislocation elastic interaction occurs, carbon, nitrogen atom gathered dislocations around the line. This combination of carbon, nitrogen atom and the dislocation line, said the year-old Korotkoff air mass (Ke lop air mass). It makes the strength and hardness of the steel to improve the ductility and toughness is reduced, a phenomenon known as deformation aging. Deformation greater harm than quench aging on the ductility and toughness of low carbon steel, hot dip galvanized steel pipe apparent on low carbon steel tensile curve, under two yield point. Since the upper yield point until the end of the yield elongation, the sample surface due to uneven deformation and surface formed folds belt, called Luders band. Many stampings often scrapped. Which prevents the two ways. A high pre-deformation method, pre-deformation of steel stamping place for some time will produce Luders band, so the pre-deformation of steel storage time should not be too long before the punching.