Purpose of 4140 Steel Pipe produced by China Steel Pipe Factory: the special steel grade for bridge is "4140", the special steel grade for automobile girder is "4140", and the special steel grade for pressure vessel is "4140". This kind of steel depends on adjusting the carbon content (c) to improve the mechanical properties of steel.
Therefore, according to the carbon content, this kind of steel can be divided into: low carbon steel - the carbon content is generally less than 0.25%, such as 1010 and 1020 steel; Medium carbon steel - the carbon content is generally between 0.25 ~ 0.60%, such as 1035 and 1045 steel; High carbon steel - carbon content is generally greater than 0.60%. This kind of steel is not generally used in the manufacture of steel pipes.
Obvious tempering brittleness and small deformation during quenching. After quenching and tempering treatment, China Baote steel pipe plant has high fatigue limit and multi impact resistance, good impact toughness at low temperature, and high creep strength and lasting strength at high temperature. 4140 seamless steel pipe plant usually takes surface quenching after quenching and tempering as the heat treatment scheme.
According to different production methods, China seamless steel pipe plant is divided into hot-rolled pipe, cold-rolled pipe and cold drawn pipe, with their own process regulations. The materials include ordinary and high-quality carbon structural steel (A570 / a570m and 1010 ~ 1050 steel), low alloy steel (a210-c, etc.), alloy steel, stainless and acid resistant steel, etc.
According to the purpose, it can be divided into general purpose (for water transmission, gas pipeline, structural parts and mechanical parts) and special purpose (for boiler, geological exploration, bearing, acid resistance, etc.).
Chemical composition (mass fraction) of 4140 seamless steel pipe: Ni ≤ 0.030%, P ≤ 0.030%, s ≤ 0.030%
ASTM 4140 steel pipe classification
The requirements for different quality levels are as follows: a - provide s, P, C, Mn, Si chemical composition and Fu, FY δ 5（ δ 10) , 1800 cold bending test can be provided according to the buyer's needs, but there is no impact energy regulation, and the carbon content and manganese content are not taken as the delivery conditions. B - provide s, P, C, Mn, Si chemical composition and Fu, FY δ 5（ δ 10) , cold bend 180 'test.