Classification of China’s steel numbering method

Carbon structural steel

① by q + number + quality grade symbols + deoxidation method symbols. Its steel number is crowned with “q”, on behalf of the yield point of steel, followed by the number of yield point values, the unit is mpa, such as q235 the yield point (σs) for 235 mpa of carbon structural steel.

② If necessary, the steel number can be marked behind the symbols indicating the quality level and deoxidation method. Quality level symbols were a, b, c, and d. Oxygen removal method symbols: f means boiling steel; b means semi-sedated steel: z means sedated steel; tz means special sedated steel, sedated steel can not be labeled symbols, that is, z and tz can not be labeled. For example, q235-af means a level of boiling steel.

③ Special-purpose carbon steel, such as bridge steel, marine steel, etc., basically uses the representation of carbon structural steel, but in the steel number at the end of the additional letters indicating the use.

High-quality carbon structural steel

① Two digits at the beginning of the steel number indicate the carbon content of the steel to the average carbon content of a few ten-thousandths of the said, for example, the average carbon content of 0.45% of the steel, steel number for the “45”, which is not the order of the number, so you can not read into the 45 steel.

② high manganese content of high-quality carbon structural steel, manganese should be marked out, such as 50mn.

③ Boiling steel, semi-sedated steel, and special-purpose high-quality carbon structural steel should be specially marked at the end of the steel number, such as the average carbon content of 0.1% of semi-sedated steel, its steel number is 10b.

Carbon tool steel

① steel number crowned with “t”, so as not to be confused with other steels.

② steel number in the number of carbon content, to the average carbon content of a few thousandths. For example, “t8” indicates that the average carbon content is 0.8%.

③ Manganese content is higher in the steel number marked at the end of the “mn”, such as “t8mn”.

④ High-quality carbon tool steel phosphorus, and sulfur content, lower than the general quality of carbon tool steel, in the steel number at the end of the letter “a”, to show the difference, such as “t8mna”.

Free-cutting steel

① steel number crowned with “y”, to distinguish it from high-quality carbon structural steel.

② letter “y” after the number of carbon content, the average carbon content of a few ten-thousandths of the said, such as the average carbon content of 0.3% of the free cutting steel, the steel number for “y30”.

③ Manganese content is higher, but also in the steel number after the label “mn”, such as “y40mn”.