It consists of Q+number+quality grade symbol+deoxidation method symbol. Its steel number is prefixed with "Q", which represents the yield point of the steel. The following number represents the yield point value in MPa. For example, Q235 represents a carbon structural steel with a yield point (σs) of 235 MPa. ② If necessary, symbols indicating the quality grade and deoxidation method can be marked after the steel number. The quality grade symbols are A, B, C, and D respectively. Deoxidation method symbols: F represents boiling steel; b represents semi-killed steel; Z represents killed steel; TZ represents special killed steel. Killed steel does not need to be marked with symbols, that is, both Z and TZ do not need to be marked. For example, Q235-AF represents Grade A boiling steel.
Special-purpose carbon steel, such as bridge steel, marine steel, etc., basically uses the representation method of carbon structural steel, but a letter indicating the purpose is appended to the end of the steel number.
Q235B element content
Carbon C: ≤0.20%
Silicon Si: ≤0.35%
Manganese Mn: ≤1.4%
Sulfur S: ≤0.045%
Phosphorus P: ≤0.045%
Chromium Cr: Allowable residual content ≤0.30%
Nickel Ni: Allowable residual content ≤0.30%
Copper Cu: Allowable residual content ≤0.30%
Note: Deoxidation method: F, b, Z
