China has developed different steel codes and numbers to identify different types of steel. The national standard, the GB/T 222 “Permissible Tolerances for Chemical Composition of Steel Products”, is the basis for the standardization of the various types of steel’s composition in China. Steel grade codes are divided into several groups according to its composition and properties, such as carbon steel codes, low alloy steel codes, high-alloy steel codes, and stainless steel codes.
The carbon steel codes are a three-digit number letter numbered system. The first number represents the amount of carbon in the steel, ranging from 1 for low-carbon steels (0.007% carbon or lower) to 9 for ultralow carbon steels. The middle digit is a letter indicating the amount of manganese added to the steel and the third number is used to indicate other elements like copper (Cu), nickel (Ni) and silicon (Si). For example, 10H2Mn indicates a low carbon steel with 0.10% carbon and 2% Manganese.
Low alloy steel codes are also classified by a three-digit numbering system. The first number represents the amount of carbon in the steel. The last two digits indicate the amount of alloying elements such as: chromium (Cr), molybdenum (Mo), vanadium (V), Silicon (Si) and boron (B). For example, 15CrMoV indicates a low alloy steel with 0.15% carbon, 0.50% chromium, 0.25% molybdenum and 0.05% vanadium.
High-alloy steel codes are are classified differently compared to other steel codes. These codes typically contain more characters. The first two digits indicate the amount of carbon in the steel with the last two digits indicating the amounts of alloying elements like nickel (Ni), chromium (Cr), molybdenum (Mo) etc. For example, Ni-Cu-08CrMoV indicates a high alloy steel with 0.8% carbon, 8% chromium,0.3% molybdenum, 1% nickel and 0.3% copper.
Lastly, stainless steel codes are similar to high-alloy steel codes, but the last two digits indicate the amount of chromium (Cr) and nickel (Ni) in the steel. For example, 00Cr17Ni14Mo2 indicates a stainless steel having 17% chromium, 14% nickel, and 2% molybdenum.
By categorizing steel into these codes, it is easier for steel producers, buyers, and sellers to identify and specify the type of steel they are dealing with. With the right know-how and information, all parties are able to make the most informed decisions.
