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Seamless steel pipe
Seamless steel pipe

Seamless steel pipe

Made of the whole metal, no seams on the surface of the steel tube, known as seamless steel tube, according to ...
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A steel tube made of a single piece of metal with no seams on the surface is called a seamless steel tube. According to the production method, seamless tube can be divided into hot rolling tube, cold rolling tube, cold drawing tube, extrusion tube, tube jacking, etc. According to the section shape, the seamless steel pipe divides into the circular and the profiled two kinds, the profiled tube has the square, the elliptic, the triangle, the hexagon, the melon seed shape, the star, takes the wing tube many kinds of complex shapes. The diameter is 650mm with a small diameter of 0.3mm. According to different USES, there are thick wall tube and thin wall tube. Seamless steel pipe is mainly used for petroleum geological drilling pipe, cracking pipe for petrochemical industry, boiler and furnace pipe, bearing pipe and high-precision structural steel pipe for automobile, tractor and aviation.

Seamless steel pipes are widely used. The general purpose seamless steel pipe is rolled by ordinary carbon structural steel, low alloy structural steel or alloy structural steel. 2, according to the use of different types of supply: a, according to chemical composition and mechanical properties supply; B. Supply according to mechanical performance; C. Supply according to hydraulic test. Steel pipes supplied in class a and b, if used to withstand liquid pressure, should also be hydrostatic tested. 3, the special use of seamless tube for boilers, chemical power, seamless steel tube for geology and seamless pipe for petroleum, and so on.

Seamless steel pipe with hollow section, a large number of fluid transport pipelines, such as oil, natural gas, gas, water and some solid materials pipeline. Compared with round steel and other solid steel, steel pipe has the same bending and torsional strength, and the weight is lighter.

It is widely used in the manufacture of structural parts and mechanical parts, such as oil drill pipe, automobile transmission shaft, bicycle frame and steel scaffolding used in building construction, etc. Steel pipe is widely used in the manufacture of circular parts, which can improve the utilization rate of materials, simplify the manufacturing process, and save materials and processing hours.

Seamless steel tube production process

(1) hot rolling seamless steel tube main production process (△ main inspection process) :

Tube billet preparation and inspection △ tube billet heating → perforation → tube rolling → steel tube heating → constant (reduced) diameter → heat treatment △ finished tube straightening → finishing → inspection △ (nondestructive, physical and chemical, table inspection) → warehousing

(2) cold rolling (drawing) seamless steel tube main production process:

Preparation → pickling and lubrication → cold rolling (drawing) → heat treatment → straightening → finishing → inspection

General seamless steel tube production process can be divided into cold drawing and hot rolled, cold rolled seamless steel tube production process generally more complicated than hot rolled, three roller rolling tube billet to be first, after the extrusion sizing test, if there is no response after crack on the surface of pipe have to be cut after cutting machine, cutting grow about a meter of billet. Then it goes into the annealing process. During the pickling, attention should be paid to whether there are a lot of bubbles on the surface. If there are a lot of bubbles, the quality of the steel pipe cannot meet the corresponding standards. The appearance of cold-rolled seamless steel tube is shorter than hot-rolled seamless steel tube, cold-rolled seamless steel tube wall thickness is generally smaller than hot-rolled seamless steel tube, but the surface looks brighter than the thick-walled seamless steel tube, the surface does not have too much roughness, diameter is not too much burr.

Hot - rolled seamless steel tube delivery state is generally hot - rolled state after heat treatment for delivery. Hot rolled seamless steel tube after quality inspection to be strictly hand-selected by the staff, after the quality inspection to carry out surface coating, followed by a number of cold drawing experiments, hot rolled after the perforation test, if the perforation expansion is too large to be straightened and corrected. After straightening, the device is transferred to the flaw detection machine for flaw detection test, labeled, and placed in the warehouse after specification arrangement.

Round tube billet → heating → perforation → three-roll cross rolling, continuous rolling or extrusion → tube off → sizing (or reducing) → cooling → straightening → hydraulic test (or flaw detection) → marking → warehousing of seamless steel pipe is made of steel ingot or solid tube billet through perforation into capillary tube, and then made by hot rolling, cold rolling or cold drawing. The specification of seamless steel pipe is expressed by outer diameter * wall thickness mm number.

The outer diameter of hot rolled seamless pipe is generally more than 32mm, wall thickness 2.5-200mm, cold rolled seamless pipe outer diameter can be to 6mm, wall thickness can be to 0.25mm, thin wall diameter can be to 5mm wall thickness is less than 0.25mm, cold rolling than hot rolling dimensional accuracy.

Generally used seamless steel pipe is 10, 20, 30, 35, 45 and other carbon junction steel 16Mn, 5MnV and other low alloy structure steel or 40Cr, 30CrMnSi, 45Mn2, 40MnB and other combined steel hot rolling or cold rolling made. 10, 20 and other low carbon steel manufacturing seamless tube is mainly used for fluid transport pipeline. Seamless tubes made of medium carbon steel such as 45 and 40Cr are used to make mechanical parts, such as stressed parts of cars and tractors. Generally used seamless steel tube to ensure the strength and flattening test. Hot rolled steel tube in hot rolling state or heat treatment state delivery; Cold rolling delivery in heat treatment condition.

Hot rolling, as the name implies, rolled pieces of high temperature, so the deformation resistance is small, can achieve large deformation. Take the rolling of steel plate as an example, the general thickness of continuous casting billet is about 230mm, while the final thickness is 1~20mm after rough rolling and fine rolling. At the same time, due to the small width and thickness ratio of the steel plate, the dimensional accuracy requirements are relatively low, not easy to appear plate shape problems, mainly to control the crown. For the organization requirements, generally through the control of rolling and cooling to achieve, that is, to control the fine rolling of the rolling temperature, the final rolling temperature.