1 alloy structural steel grades using Arabic numerals and standard chemical element symbols, said. Two Arabic numerals, the average carbon content (very few) on the head grade.
Representation of the content of alloying elements are: the average concentration of less than 1.50%, grade only marked elements, generally do not indicate the content; average alloy content of 1.50% ~ 2.49% 2.50% 3.49% 3.50% 4.49%, 4.50% to 5.49%, ..., corresponding alloying elements written in 2, 3, 4, 5 ...
For example: the average content of carbon, chromium, manganese, silicon 0.30%, 0.95%, 0.85%, 1.05% of the alloy structural steel, S, P content ≤ 0.035%, the grade expressed as 30CrMnSi ".
High quality alloy structural steel (S, P content ≤ 0.025%), said Grade tail plus symbol "A". For example: "30CrMnSiA."
Premium quality alloy steel (S ≤ 0.015%, P ≤ 0.025%) in grades rear plus sign in the "E", for example: "30CrM nSiE".
Special alloy steel grades there should be provisions in the head grade (or tail) and Table 1 the use of symbols represent the product. For example, Heading a dedicated 30CrMnSi steel, steel ML30CrMnSi.
② alloy spring steel grades, the representation and the same alloy structural steel.
For example: the average content of carbon, silicon, manganese, respectively, 0.60%, 1.75%, 0.75% of the spring steel, the grade is expressed as 60Si2Mn. High quality spring steel in the grades of rear plus sign in the "A" grade is expressed as "60Si2MnA.