Carbon steel can be further divided into low carbon steel, medium carbon steel and high carbon steel, mainly depending on the carbon content in the steel.

Mild steel (also known as light steel): The carbon content is usually between 0.04% and 0.30%. Low carbon steel has good ductility and toughness, can be processed hot and cold, and is easy to weld. Commonly used low carbon steels include Q195, Q215, Q235, etc.
Medium carbon steel: The carbon content is usually between 0.30% and 0.60%. Medium carbon steel has high strength and hardness, but low ductility and toughness. Commonly used medium carbon steels include 45# steel, 40Cr and so on.
High Carbon Steel: The carbon content is usually between 0.60% and 2.00%. High carbon steel has high strength and hardness, but low ductility and toughness, and poor weldability. Commonly used high carbon steels include 65Mn, T8, T10, etc.

Carbon steel pipes can be divided into seamless steel pipes and welded steel pipes according to the production method. Seamless steel pipes are made by hot rolling or cold drawing, and have high strength and tightness. Welded steel pipe is made by rolling steel plate or steel strip into a cylindrical shape, and then connecting the weld seams by resistance welding, submerged arc welding and other methods.