Commonly used metal material grade expression method

Alloy structural steel and alloy spring steel grade expression method
--Alloy structural steel grades using Arabic numerals and standard chemical element symbols to indicate
The average carbon content (in parts per million) is expressed in two Arabic numerals and placed at the head of the grade. Alloying element content is expressed as follows: when the average content is less than 1.50%, only the element is marked in the grade, and the content is generally not marked; the average alloying content of 1.50% ~ 2.49%, 2.50% ~ 3.49%, 3.50% ~ 4.49%, 4.50% ~ 5.49%, ......, when the alloying element is written as 2, 3, 3, 3, 3, 4, 5.49%, 5.49%, 4.50% ~ 5.49% and 5.49% accordingly after the grade. When ......, in the alloying elements written after the corresponding 2, 3, 4, 5 ....... For example: carbon, chromium, manganese, silicon, the average content of 0.30%, 0.95%, 0.85%, 1.05% of the alloy structural steel, when the S, P content of ≤ 0.035%, its grade is expressed as "30CrMnSi". Advanced high-quality alloy structural steel (S, P content of ≤ 0.025%), in the end of the sign plus the symbol "A" said. For example: "30 CrMnSiA". Special high-quality alloy structural steel (S ≤ 0.015%, P ≤ 0.025%), add the symbol "E" at the end of the grade, for example: "30CrM nSiE".
Special alloy structural steel grades should also be in the grade head (or tail) plus a symbol representing the use of the product.
--Alloy spring steel grades are expressed in the same way as alloy structural steel.
For example: carbon, silicon, manganese, the average content of 0.60%, 1.75%, 0.75% of the spring steel, the grade is expressed as "60Si2Mn". High-quality spring steel, add the symbol "A" at the end of the sign, the sign is expressed as "60Si2MnA".

Free-cutting steel grade expression
Free cutting steel using standard chemical element symbols, symbols and Arabic numerals specified in Table 1. The Arabic numerals indicate the average carbon content (in parts per million).
a, plus sulfur free cutting steel and sulfur, phosphorus free cutting steel, in the symbol "Y" and the Arabic numerals are not added after the free cutting element symbols. For example: free cutting steel with an average carbon content of 0.15%, the grade is shown as "Y15".
b, higher manganese content of sulfur or sulfur, phosphorus free cutting steel in the symbol "Y" and the Arabic numerals after the addition of manganese element symbols. For example: the average carbon content of 0.40%, manganese content of 1.20% ~ 1.55% of free cutting steel, its grade is expressed as "Y40Mn".
c, containing calcium, lead and other free-cutting elements of free-cutting steel, in the symbol "Y" and the Arabic numerals after the addition of free-cutting element symbols. For example: "Y15Pb", "Y45Ca".
--Non-tempered mechanical structural steel grade representation of non-tempered mechanical structural steel, in the head of the grade were added symbols "YF" and "F" for free-cutting non-tempered mechanical structural steel and hot forging non-tempered mechanical structural steel. Non-tempered mechanical structural steel for hot forging, the other contents of the grade numbering method are the same as the alloy structural steel. For example: "YF35V", "F45V".