Compared with ordinary carbon structural steel, high-quality carbon structural steel has lower content of sulfur, phosphorus and other non-metallic inclusions. According to the different carbon content and application, this kind of steel can be roughly divided into three categories, namely low carbon steel, medium carbon steel and high carbon steel.
Less than 0.25% C is low-carbon steel, especially 08F and 08Al with a carbon content of less than 0.10%. Low-carbon steel is widely used as deep-drawing parts such as automobiles because of its good deep drawability and weldability. Canning, etc. 20G is the main material for making ordinary boilers. In addition, low carbon steel is also widely used as carburizing steel for machinery manufacturing.
0.25~0.60%C is medium carbon steel. Medium carbon steel is mostly used in the quenched and tempered state to make parts in the machinery manufacturing industry. Quenching and tempering is 22~34HRC, which can obtain comprehensive mechanical properties and facilitate cutting.
More than 0.6% C is high carbon steel. High carbon steel is mostly used to make springs, gears, rolls, etc. According to the different manganese content, it can be divided into ordinary manganese content (0.25~0.8%) and higher manganese content (0.7~1.0% and 0.9~1.2% ) two steel groups. Manganese can improve the hardenability of steel, strengthen ferrite, improve the yield strength, tensile strength and wear resistance of steel. Usually, the mark "Mn" is added after the grade of steel with high manganese content, such as 15Mnīš20Mn, to distinguish it from carbon steel with normal manganese content.
