1. Ordinary carbon structural steel: Carbon structural steel is divided into five grades according to the yield strength of the steel: Q195, Q215, Q235, Q255, and Q275. Each grade is divided into grades A, B, C, and D due to different quality. Q195, Q215, and Q235 have good plasticity and can be rolled into steel plates, steel bars, steel pipes, etc.; Q255, Q275 can be rolled into profiled steel, steel plates, etc.

2. High-quality carbon structural steel: the steel number is expressed in ten thousand parts per thousand of the average mass of carbon. Such as 20#, 45# and so on. 20# means containing C: 0.20% (20/10,000), use: mainly used in the manufacture of various machine parts

3. Carbon tool steel: The steel number is represented by the average mass dry fraction of carbon, and is prefixed with T. Such as T9, T12, etc. T9 means containing C: 0.9% (dry part 9) Uses: Mainly used in the manufacture of various knives, measuring tools, molds, etc.