① The two digits at the beginning of the steel grade indicate the carbon content of the steel, expressed as a fraction of the average carbon content, such as 40Cr.

② The main alloying elements in steel, except for a few microalloying elements, are generally expressed in percentages. When the average alloy content is less than 1.5%, the steel grade generally only indicates the element symbol without indicating the content, but

For those who are prone to confusion in special circumstances, the number '1' can also be marked after the element symbol, such as steel grades' 12CrMoV 'and' 12Cr1MoV '. The former has a chromium content of 0.4-0.6%, while the latter is

0.9-1.2%, all other components are the same. When the average content of alloying elements is ≥ 1.5%, ≥ 2.5%, ≥ 3.5%..., the content should be indicated after the element symbol, which can be expressed as 2, 3, etc

4... wait. For example, 18Cr2Ni4WA.

③ Vanadium V, titanium Ti, aluminum AL, boron B, rare earth RE and other alloying elements in steel are all microalloying elements. Although their content is very low, they should still be marked in the steel grade. For example, in 20MnVB steel. Vanadium is 0.07-0.12%, boron is 0.001-0.005%.

④ High quality steel should be marked with 'A' at the end of the steel grade to distinguish it from regular high-quality steel.