What is the representation of alloy structural steel?
The two digits at the beginning of the steel number indicate the carbon content of the steel, expressed as a few ten thousandths of the average carbon content, such as 40Cr.
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 number is generally marked with the element symbol instead of the content. However, in special circumstances that may cause confusion, the number "1" can also be marked after the element symbol, such as the steel number. "12CrMoV" and "12Cr1MoV", the former has a chromium content of 0.4-0.6%, the latter has a chromium content of 0.9-1.2%, and the rest of the ingredients are the same. When the average content of alloy elements is ≥1.5%, ≥2.5%, ≥3.5%..., the content should be indicated after the element symbol, which can be expressed as 2, 3, 4... etc. accordingly. For example 18Cr2Ni4WA.
Alloying elements such as vanadium V, titanium Ti, aluminum AL, boron B, and rare earth RE in steel are all micro-alloying elements. Although the content is very low, they should still be marked in the steel grade. For example, in 20MnVB steel. Vanadium is 0.07-0.12%, and boron is 0.001-0.005%.
High-grade high-quality steel should be distinguished from general high-quality steel by adding "A" at the end of the steel number.
Special-purpose alloy structural steel, the steel number is preceded (or suffixed) with a symbol representing the purpose of the steel type. For example, 30CrMnSi steel specially used for rivet screws, the steel number is expressed as ML30CrMnSi.
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