What does 1 in 12Cr1MoV steel stand for

What does 1 in 12Cr1MoV steel represent?
This should start from the way of steel grade designation. The main alloy elements in steel, except individual microalloying elements, are generally expressed in several percent. When the average alloy content is less than 1.5%, only the element symbol is marked in the steel grade, but not the content.

However, under special circumstances, it is easy to be confused, and the number "1" can also be marked after the element symbol, such as steel grade "12CrMoV" and "12Cr1MoV steel". The chromium content of the former is 0.4-0.6%, the latter is 0.9-1.2%, and the other components are all the same.

When the average content of alloying elements ≥ 1.5%, ≥ 2.5%, ≥ 3.5% ..., the content should be indicated after the element symbol, which can be expressed as 2, 3, 4 etc. For example, 18Cr2Ni4WA.