Carbon structural steel
1. Composed of q+number+quality grade symbol+deoxidation method symbol. The steel number of carbon structural steel is prefixed with "q", which represents the yield point of the steel, and the number behind it indicates 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.
2. If 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 symbols: f means boiling steel; b means semi-killed steel; z means killed steel; tz means special killed steel, and the killed steel can be free from symbols, that is, both z and tz can not be marked. For example, q235-af means a grade boiling steel.
3. Carbon steel for special purposes, such as bridge steel, marine steel, etc., basically uses 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
1. The 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 into No. 45 steel.
2. For high-quality carbon structural steel with high manganese content, the manganese element should be marked, such as 50mn.
3. Boiling steel, semi-killed steel and high-quality carbon structural steel for special purposes 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.
