Carbon characteristics of seamless pipes

What is seamless pipe?

Seamless pipe means a steel pipe that is perforated from a whole round steel and has no welds on the surface. Because the seamless pipe has a hollow section, it is widely used as a pipeline for transporting fluids, such as pipelines for transporting oil, natural gas, gas, water and certain solid materials. Compared with solid steel such as round steel, the steel pipe is lighter in weight when the bending and torsional strength is the same, and is an economical section steel.

Classification of seamless pipes according to carbon content

1) General carbon content precision seamless pipe

Generally, steel with carbon content ≤ 0.25% is called high carbon steel. The quenching mechanism of high carbon steel is metallographic structure and a small amount of ferrite. Its compressive strength and strength are low, and its plastic deformation and ductility are good, which is convenient for drawing and stamping. Die, extrusion, forging and electric welding, among which 20Cr steel is mainly used. The steel has a certain compressive strength. After heat treatment and ultra-low temperature quenching, this type of steel has excellent comprehensive physical properties, excellent ultra-low temperature fracture toughness, and insignificant quenching ductility.

Main use: suitable for making electric welding parts and their parts that are not subjected to high ground stress by forging, hot stamping dies and machining in the machining industry, and are useful in the steam turbine generator and heating furnace processing industry Water pipes, flanges, headers and various standard parts in work in non-corrosive substances; also suitable for large, medium and small nitriding, carbonitriding, etc. in the production of small cars, large tractors and general machining industries Parts, such as brake shoes, lever shafts, inner and outer shaft sleeves of balancers, etc.; in heavy, medium and small machining industries, such as forged or suppressed support rods, shackles, levers, sleeve specifications, Tooling fixtures, etc.

2) High carbon steel precision seamless pipe

High carbon steel nitriding: after the high carbon steel with a carbon water content of about 0.15% is carburized and quenched and ultra-low temperature quenched, it is used to specify the surface with high strength and good wear resistance. Injection molds and other parts. After carburizing and quenching and ultra-low temperature quenching, the high carbon steel obtains a structure in which the surface layer is high carbon steel austenite and the core is low carbon environmental austenite, thereby ensuring that the surface layer has high toughness, high wear resistance and the core has high very good compressive strength and ductility. Suitable for the production of brake shoes, lever shafts, transmission speed forks, transmission gears, and engine camshafts on large tractors, suspension balancer shafts, balancer inner and outer bushings, sleeve specifications, tooling fixtures and other parts.

3) Low carbon steel precision seamless pipe

Low carbon steel: carbon structural steel with carbon content of 0.25% to 0.60%, 30, 35, 40, 45, 50, 55 and other models belong to low carbon steel, due to the increase in ferrite water content in the steel, its compressive strength and The strength is higher than before, and the strength after heat treatment can be significantly improved. Among them, 45 steel is more typical. 45 steel is a high-toughness medium-carbon quenched and tempered steel, with certain plastic deformation and ductility, and excellent machinability. It is used to manufacture parts with high compressive strength and medium ductility. Generally used in heat treatment or quenching conditions. In order to make the steel have the necessary ductility and remove its internal stress, the steel should be quenched into sorbite after heat treatment.

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