1. Raw material preparation: The raw material of cold drawn seamless steel tube is mainly steel plate or steel belt. The quality of the raw material has a direct impact on the performance of the final product. So raw materials need to be rigorously checked to ensure that surface quality, chemical composition and mechanical properties meet the requirements .
2. Heat perforation: The raw material is heated to a certain temperature (such as 1300°C) to make it soft and easy to shape. This is followed by the formation of a hollow thick-walled capillary tube through a perforator.
3. Hot rolling (cold rolling): The capillary tube is rolled in multiple passes through the hot mill, gradually reducing the thin wall thickness to form a blank tube close to the finished product size. For products that require higher dimensional accuracy and surface quality, a cold rolling process can be employed, which is usually performed on a two-high mill.
4. Cold drawing: The seamless tube is stretched at room temperature to further reduce its outer diameter and wall thickness. It is necessary to control the drawing speed and diameter reduction rate during the cold drawing process to prevent cracks in the steel pipe.
5. Finishing: including cutting head, deburring, straightening, pickling, cold treatment, heat treatment and other steps. To prevent excessive acid from corroding the surface of the steel pipe during pickling, heat treatment is used to eliminate residual stress, improve tissue structure and improve mechanical properties .
6. Quality inspection: Comprehensive quality inspection of seamless steel pipes through ultrasonic inspection, eddy current inspection, hardness testing and other means to ensure that the products meet the standards .
1. Pressure applications: Cold-drawn seamless steel pipes perform well in high-pressure environments such as oil and gas pipelines, chemical processing, and sewage treatment, where they can resist high pressure and high temperatures .
2. Structural Materials: Due to their strength and lightweight nature, seamless steel tubes are widely used as structural materials in the automotive, bicycle, and aerospace industries.
3. Fluid Transfer: This product performs well in fluid transfer applications, such as the delivery of water, gas, and oil .
4. Machine tools: Make shafts, bearings, gears, etc.
5. Electronic Devices: The support structure that makes electronic devices.
6. Geological drilling: makes drill pipes, collars and core pipes for geological drilling.
7. Shipbuilding: pressure pipe systems, boilers and superheaters for ships.
8. Boiler manufacturing: manufacturing the boiler’s superheated steam tube and boiling water tube, etc., to withstand high temperature and high pressure environment .
9. Automobile manufacturing: Used in automobile semi-axle sleeve and drive axle housing shaft tube to improve the stability and safety of automobile .
10. Petrochemicals: furnace tubes, heat exchangers, etc. used in oil drilling and chemical equipment that withstand high pressure and corrosive environments .
11. Other fields: fertilizer equipment, hydraulic and pneumatic cylinders, diamond core drilling, etc.
First of all, in terms of process principle, cold drawing is a process of stretching metal materials at room temperature. Through extrusion and stretching of the mold, the cross section of metal materials is reduced, the length is increased, and the strength and hardness are improved. While hot rolling is to roll the metal material at high temperature, through the extrusion and friction of the roller, so that the metal material plastic deformation, so as to achieve the desired shape and size.
Secondly, in terms of performance, cold drawn metal materials have high strength and hardness, but relatively low toughness, and good surface finish. Hot rolled metal materials have good toughness and ductility, but the strength and hardness may be relatively low, and the surface may have defects such as oxide scale.
In terms of operation, the cold drawing process requires precise die design and strict temperature control to ensure precise deformation of the metal material and high quality output. At the same time, the tensile force in the cold drawing process is large, which requires professional equipment and operation skills. Hot rolling process is relatively simple, the requirements for equipment and operation skills are low, and the production efficiency is high.
1.High dimensional accuracy: in the production process of cold drawn seamless pipe, because it is carried out at room temperature, the deformation of the steel pipe can be accurately controlled, so as to ensure the high dimensional accuracy of the product.
In contrast, hot-rolled seamless pipes are produced at high temperatures, with large deformation and relatively poor dimensional accuracy.
2.Good surface quality: cold drawing process makes the steel pipe deformation at room temperature, its surface is not easy to produce oxide scale and crack, so as to ensure good surface quality.
The hot-rolled seamless tube is produced at high temperature, and the surface is easy to produce oxide scale, which needs to be removed by subsequent treatment.
3.Strong mechanical properties: in the deformation process of cold drawn seamless pipe, the internal structure of the steel pipe is refined, and the grain is evenly distributed, thus improving its mechanical properties, such as strength, hardness and toughness.
Although the hot rolled seamless pipe also has certain mechanical properties, but compared with the cold drawn seamless pipe, its performance may be slightly inferior.
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