The steel number of the
large diameter spiral tube includes:
Carbon structural steel
1. It consists of Q+number+quality grade symbol+deoxidation method symbol. Its steel number is "Q", which represents the yield point of the steel, and the latter number represents the value of the yield point. The unit is MPa. For example, Q235 represents a carbon structural steel with a yield point (σs) of 235 MPa.
2. If necessary, the symbol of the quality grade and deoxidation method can be marked after the steel number. The quality level symbols are A, B, C, and D, respectively. The deoxidation method symbol F indicates boiling steel, B indicates semi-calcined steel, Z indicates calming steel, TZ indicates special calming steel, and calming steel may not be marked, that is, both ZT and TZ may not be marked. For example, Q235-AF represents Class A boiling steel.
3. Carbon steel for special purposes, such as bridge steel and marine steel, basically adopts the representation method of carbon structural steel, but the letter indicating the use is added at the end of the steel number.
Carbon tool steel
1. The steel number is crowned with “T” to avoid mixing with other steels.
2. The number in the steel number indicates the carbon content, expressed as a few thousandths of the uniform carbon content. For example, "T8" means a uniform carbon content of 0.8%.
3. For those with higher manganese content, “Mn” is marked at the end of the steel number, for example “T8Mn”.
4. The phosphorus and sulfur content of carbon tool steel is lower than that of ordinary high-quality carbon tool steel. The letter “A” is added at the end of the steel number to distinguish it, for example, “T8MnA”.
