Characteristics:
1. Seamless low carbon steel pipe is a carbon steel with a carbon content of less than 0.25%. It is also called mild steel because of its low strength, low hardness and softness.
2. The annealed structure of seamless low carbon steel pipe is ferrite and a small amount of pearlite, which has low strength and hardness, and good plasticity and toughness.
3. Seamless low carbon steel pipe has good cold formability and can be cold formed by crimping, bending, stamping, etc. 4.
Seamless low carbon steel pipe has good weldability. Easy to accept a variety of processing such as forging, welding and cutting.
Heat treatment:
Seamless low carbon steel pipes have a strong aging tendency, both cooling and aging tendencies, as well as deformation and aging tendencies. When the steel is cooled at high temperature, the carbon and nitrogen in the ferrite are supersaturated, and the carbon and nitrogen in the iron can be formed slowly at normal temperature, so that the strength and hardness of the steel are improved, and ductility and toughness are reduced. This phenomenon is called extinction aging. Seamless low carbon steel pipes will have an aging effect even if they are not quenched. The deformation of seamless low carbon steel pipes produces a large number of dislocations. The carbon and nitrogen atoms in ferrite interact elastically with the dislocations, and the carbon and nitrogen atoms gather around the dislocation lines. This combination of carbon and nitrogen atoms and dislocation lines is called a Cochrane gas mass (Kelly gas mass). Increases the strength and hardness of steel and reduces ductility and toughness. This phenomenon is called strain aging. Strain aging is more detrimental to the ductility and toughness of low carbon steel than quench aging. There are obvious upper and lower performance points on the tensile curve of low carbon steel. From the upper yield point to the end of the yield extension, a band of surface wrinkles formed on the surface of the sample due to uneven deformation is called the Rydes belt. Many stamping parts are often thrown away. There are two ways to prevent it. A high pre-deformation method, the pre-deformed steel is placed for a period of time and the Rudes strap is also produced when stamping, so the pre-deformed steel should not be placed for too long before stamping. The other is to add aluminum or titanium to steel to form a stable compound with nitrogen to prevent strain aging caused by the formation of Kodak air mass.
