It is a long strip of steel with a hollow section and no seams around it. Steel pipes have a hollow section and are used in large quantities as pipes for transporting fluids, such as pipes 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 it has the same bending and torsional strength. It is an economical section steel and is widely used in the manufacture of structural parts and mechanical parts, such as oil drill pipes, automobile transmission shafts, bicycles. Shelf and steel scaffolding used in construction.
The use of steel pipes to manufacture ring-shaped parts can improve material utilization, simplify manufacturing processes, save materials and processing man-hours, such as rolling bearing rings, jacks, etc., and have been widely used in steel pipes. Steel pipes are also indispensable materials for various conventional weapons, and barrels, barrels, etc. are all made of steel pipes. Steel pipes can be divided into round pipes and shaped pipes according to the shape of the cross-sectional area. Since the area of the circle is the largest under the condition of equal circumference, more fluid can be transported by the circular tube. In addition, the circular section is subjected to a relatively uniform force when subjected to internal or external radial pressure, and therefore, most of the steel pipes are round pipes. The following describes the difference between cold drawn seamless steel pipe and hot drawn seamless steel pipe:
1) The difference between hot processing and cold working: hot rolling is hot processing, cold drawing is cold processing
2) The main difference: hot rolling is rolling above the recrystallization temperature, cold rolling is rolling below the recrystallization temperature; cold rolling sometimes has heating, but the temperature is lower, because after cold rolling Work hardening occurs, and annealing is performed if the molding requirements for the material are relatively high.
Cold rolling and hot rolling are generally sheets or profiles, while cold drawing is generally a cylindrical section of wire. In addition, the hot-rolled sheet is generally a steel with a high alloy content and high strength, while the cold-rolled steel is a low-carbon low-alloy steel, which can be strengthened by cold rolling to ensure the surface quality of the material. The difference between cold drawn seamless steel pipe and hot rolled seamless steel pipe is different from that of the plate.
Seamless steel tubes are divided into hot-rolled (extruded) seamless steel tubes and cold drawn (rolled) seamless steel tubes due to their different manufacturing processes. Cold drawn (rolled) tubes are divided into two types: round tubes and shaped tubes:
Cold drawn steel pipes generally need to be drawn multiple times, and there must be corresponding stress relief annealing between each drawing to ensure the next cold drawing smoothly. From the outside, cold-rolled seamless steel pipes are often small-diameter, and hot-rolled seamless steel pipes are often large-diameter. The accuracy of cold-rolled seamless steel tubes is higher than that of hot-rolled seamless steel tubes, and the price is also higher than that of hot-rolled seamless steel tubes.
Cold drawn seamless pipes generally have a small diameter, mostly below 127 mm. Especially the outer diameter of the cold drawn seamless pipe is very high, and the length of the cold drawn seamless pipe is generally shorter than that of the hot rolled seamless pipe. In terms of wall thickness, cold drawn seamless tubes are more uniform than hot rolled seamless tubes.
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