Various foreign steel standards are a classification of steels according to their chemical composition and properties.. These standards are European standards EN, American standards ASTM and AISI, Japanese JIS standards, Chinese GB standards, international ISO standards and so on.
General classification of steels
Steel is most often classified according to the following criteria:
- by chemical composition (carbonaceous, low alloyed or stainless);
- by production method (open-hearth, converter, smelted in electric furnaces);
- by processing method (for hot or cold rolling);
- by deoxidation method (calm, semi-calm, boiling);
- by microstructure (ferritic, pearlitic, martensitic);
- by strength level (eg, for steel A240 Grade C, ASTM standard specifies strength from 515 to 655 MPa);
- on the received heat treatment (annealed, hardened and tempered, after thermomechanical treatment).
Classification of steels by carbon content
Based on carbon content, steel grades are divided into three main groups:
- low carbon steel grades, such as steel from AISI 1005 to AISI 1026, IF, HSLA, TRIP и TWIP;
- medium carbon steel grades, such as steel from AISI 1029 to AISI 1053;
- high carbon steels, such as steel from AISI 1055 to AISI 1095.
European steel classification
According to the European classification, steel grades are divided into the following groups:
- unalloyed, such as EN DC01-DC06; S235; S275;
- alloyed, such as 2CrMo4 and 25CrMo4;
- instrumental, eg, IN 1.1545; AISI / SAE W110; IN 1.2436; AISI / SAE D6;
- steel for sheets and strips;
- steel for sheets and strips, used in electrical engineering, such as EN 1.0890 и IN 1.0803.
Sometimes the same steel can have different properties when specified according to different standards. for instance, 34CrMo4 steel is set by two standards - EN and DIN. According to the EN standard, this steel has six different subgroups., whereas according to the DIN standard there are ten subgroups. In these standards, the strength properties of this steel can differ by a factor of three, depending on the thermomechanical treatment obtained..