1. Carbon steel can be divided into three categories according to its use: carbon structural steel, carbon tool steel and free-cutting structural steel. Carbon structural steel can be further divided into engineering construction steel and machine manufacturing structural steel;

2. According to the smelting method, it can be divided into open-hearth steel and converter steel;

3. According to the deoxidation method, it can be divided into boiling steel (F), killed steel (Z), semi-killed steel (b) and special killed steel (TZ);

4. According to the carbon content, carbon steel can be divided into low carbon steel (WC ≤ 0.25%), medium carbon steel (WC0.25%-0.6%) and high carbon steel (WC≥ 0.6%);

5. According to the quality of steel, carbon steel can be divided into ordinary carbon steel (higher phosphorus and sulfur content), high-quality carbon steel (lower phosphorus and sulfur content), high-grade high-quality steel (lower phosphorus and sulfur content) and special high-quality steel.