Steel number indication and specification table of large diameter steel pipes

Steel number indication and specification table of large diameter steel pipes

Carbon structural steel
① Composed of Q + number + quality grade symbol + deoxidation method symbol. Its steel number is preceded by "Q", which represents the yield point of the steel, and the number behind it represents the value of the yield point, and the unit is MPa. For example, Q235 represents a carbon structural steel with a yield point (σs) of 235 MPa.
②If necessary, the symbol indicating the quality grade and deoxidation method can be marked behind the steel number. The quality grade symbols are A, B, C, D respectively. Deoxidation method symbol F means boiling steel, B means semi-killed steel, Z means stabilized steel, TZ means special stabilized steel, and the stabilized steel may not be marked with symbols, that is, neither ZT nor TZ may be marked. For example, Q235-AF means Grade A boiling steel.
③Carbon steel for special purposes, such as bridge steel and marine steel, basically adopts the expression method of carbon structural steel, but the letter indicating the purpose is added at the end of the steel number.

High quality carbon structural steel
①The two digits at the beginning of the steel number indicate the carbon content of the steel, expressed in ten-thousandths of the average carbon content. For example, for steel with an average carbon content of 0.45%, the steel number is "45". It is not a serial number, so it cannot be read as 45 gauge steel.
② For high-quality carbon structural steel with high manganese content, the manganese element should be marked, such as 50Mn.
③The boiling steel, semi-killed steel and special-purpose high-quality carbon structural steel should be marked at the end of the steel number. For example, the steel number of semi-killed steel with an average carbon content of 0.1% is 10b.

Carbon tool steel
①The steel number is crowned with "T" to avoid mixing with other steel types.
② The number in the steel number indicates the carbon content, expressed in thousandths of the average carbon content. For example, "T8" means that the average carbon content is 0.8%.
③ For those with higher manganese content, "Mn" is marked at the end of the steel number, such as "T8Mn".
④The phosphorus and sulfur content of high-grade high-quality carbon tool steel is lower than that of general high-quality carbon tool steel. The letter "A" is added at the end of the steel number to show the difference, such as "T8MnA".

Large diameter steel pipe specification table: