42CrMo steel is an ultra-high strength steel with high strength, toughness and good hardenability. Purpose of 42CrMo seamless steel pipe: the special steel used for bridge is "42CrMo", the special steel for automobile girder is "42CrMo", and the special steel for pressure vessel is "42CrMo". This kind of steel depends on adjusting the carbon content to improve the mechanical properties of the steel. Therefore, according to the carbon content, this kind of steel can be divided into: low carbon steel - carbon content is generally less than 0.25%, such as 10, 20 steel, etc.; medium carbon steel - carbon content is generally between 0.25% and 0.60%, such as 35, 45 steel, etc.; high carbon steel - carbon content is generally more than 0.60%. This kind of steel is generally not used for steel pipe manufacturing