1. Ordinary carbon structural steel: carbon structural steel is divided into 5 grades according to the yield strength of steel: Q195, Q215, Q235, Q255, Q275. Each grade is divided into grades A, B, C, D due to different quality. Q195, Q215, Q235 have good plasticity and can be rolled into steel plates, steel bars, steel pipes, etc.; Q255, Q275 can be rolled into section steels, steel plates, etc.
2. High quality carbon structural steel: the steel grade is expressed by the average mass ten thousand fraction of carbon, such as 20#, 45#, etc.
3. Carbon tool steel: the steel grade is expressed by the average mass per thousand of carbon, and is prefixed with T, such as T9, T12, etc.
4. Cast steel: the cast steel grade is prefixed with ZG before the number, and the number represents the average mass fraction of steel (expressed in ten thousand points), such as ZG25, which means C: 0.25%. Cast steel is mainly used to manufacture parts with complex shapes and requiring certain strength, plasticity and toughness, such as gears, couplings, etc.
