Production of large diameter Tangshan rectangular tube in Baoji
Rectangular tube is a kind of light thin-walled steel tube with hollow square section, also known as steel cold-formed section. It is a shape steel with square section and overall dimension made of Q235 hot-rolled or cold-rolled strip or coil as the base material after cold bending and forming and then high-frequency welding. Hot rolled extra thick wall square tubes, except for the thickening of wall thickness, have corner dimensions and edge straightness to the extent that they exceed the resistance welded cold formed square tubes.
Production of large diameter Tangshan rectangular tube in Baoji
1. During square forming, the corner bending is related to the neutral layer of the strip steel. The inner corner is pressed and the outer corner is pulled. No matter what method you use for square forming, the result of the corner force is that the outer tensile strip steel is thinner. From the physical phenomenon, the metal lattice changes and cold work hardening occurs. Especially when the general pass strip is hard, the corner may be broken. In addition, the dimensional accuracy of the straight square is mostly handled by sizing: first, it increases the equipment load; second, the steel strip also produces local cold work hardening, which affects the internal quality of the profile. 2. During the round to square forming, the main pipe is compressed and deformed in the pass. The pass design considers the elastic limit of the base metal, that is, the pressure must not exceed the elastic limit. If the elastic limit is exceeded, the base metal will "lose stability" and form waste products. It can be seen that the physical phenomenon of round to square forming does not change the strip. In addition, the contour and dimensional accuracy of the round to square shape is guaranteed by the hole type and adjustability, so its contour dimensional accuracy is high. Moreover, because the deformation of round to square is stopped under pressure, the thickness of its corner has an increasing trend instead of thinning, and the load resistance of profiles with the same thickness and the same specification can be significantly improved compared to the straight square.
Production of large diameter Tangshan rectangular tube in Baoji
Wall thickness grading of rectangular pipes - extra thick rectangular pipes, thick rectangular pipes, thin rectangular pipes. The thick wall rectangular pipe is a galvanized welded square pipe used for low pressure fluid escort, which is only used for ordinary low pressure fluid, mainly used for water, gas, oil, hot water or steam escort; Galvanized welded thick wall rectangular pipe for low pressure escort is mainly used to escort ordinary low pressure fluids such as water, gas, oil, hot water or steam. The surface of the square pipe adopts hot galvanizing or cold galvanizing anti-corrosion process. The rectangular thick wall mining infusion welding square tube is mainly used for mining air pressure welding, row welding, shaft drop welding, etc.
Production of large diameter Tangshan rectangular tube in Baoji
Most people think that stainless steel will not rust, and the rusty is not stainless steel. In fact, some stainless steel materials with low nickel content will rust under corresponding conditions. The stainless steel rectangular tube has the ability of resisting atmospheric oxidation and corrosion in the medium containing acid, alkali and salt. However, the corrosion resistance of steel varies with its chemical composition, additive state, application conditions and environmental medium type. Therefore, not any kind of stainless steel can resist corrosion and rust in any environment. Stainless steel forms a thin, solid and stable chromium rich oxide film on its surface to prevent oxygen atoms from penetrating the oxide layer and obtain corrosion resistance. If the membrane is damaged, the stainless steel rectangular tube will lose its rust resistance ability. There are four common destruction modes in daily life: (1) Under the condition of water and oxygen, the surface of stainless steel square tube forms organic acid, which will corrode the metal surface for a long time. (2) When encountering condensed water in the polluted air, it will form sulfuric acid, nitric acid, acetic acid and other liquid points to form chemical corrosion. (3) There is dust containing other metal elements or attachments of dissimilar metal particles on the surface of stainless steel rectangular tube. In humid air, the condensation water between the attachment and the stainless steel connects them to form a micro battery, causing electrochemical reaction and destroying the maintenance film, which is called electrochemical corrosion. (4) The stainless steel rectangular tube has acid, alkali and salt on its surface, causing partial corrosion.
Production of large diameter Tangshan rectangular tube in Baoji
The surface of fake and inferior square tubes is often pitted. The pitted surface is the irregular concave and convex defect on the surface of the square tube caused by the serious wear of the rolling groove. Because the fake and inferior square tube manufacturers want to pursue profits, the appearance of low-quality square tubes shows pockmarks. This defect often runs through the longitudinal direction of the entire product. The reason for folding is that fake and inferior manufacturers pursue efficiency and technological transformation, and there are many impurities. The rough part of the guide equipment of the fake and inferior material manufacturer is used to investigate the reason why the appearance of the inferior square tube shows pitted surface. The excessive reduction leads to the extremely cold period. The reason why the appearance of the inferior square tube produces pitted surface is that the strength of the square tube drops greatly. The appearance of fake and inferior square tubes is easy to produce scars. There are two reasons: 1. The materials of fake and inferior square tubes are uneven, and the grooved rolling often exceeds the standard. 2. Fake square tubes are easy to fold. Folding is the cause of various broken lines formed on the surface of square tubes. The surface of low-quality square tubes shows pockmarks. The folded products will crack after bending, and fold will occur during the next rolling. These impurities are easy to produce scars after biting the rolls. The reason why the poor quality square tube appears pitted surface when the speed is reduced. Our square tubes will not appear pitted, because we will not produce inferior square tubes.
Production of large diameter Tangshan rectangular tube in Baoji
Due to the different properties of seamless square and rectangular tubes, the behaviors reflected by the data are different; The mechanical performance indicators are all performance indicators under the static seamless square tube. Whether in the static tensile test or hardness test, the seamless square tube is slowly added to the sample or workpiece. However, in consumption practice, many workpieces accept the impact of seamless rectangular tubes, that is, seamless rectangular tubes act on workpieces at a great speed, such as the hook between train carriages when the train starts or stops. When the gear is shifting; The seamless square and rectangular tubes that the forging die and the stamping die are subjected to when they are working belong to this category. The difference between the impact seamless square tube and the static load is that the static load is simply the function of force, while the impact seamless square tube has the speed problem of force besides the function of force. Since it is extremely complicated to measure the impact stress on the workpiece under the impact seamless rectangular tube, it is convenient to think about the problem from the concept of energy, so the impact seamless rectangular tube can be regarded as an energy seamless rectangular tube. Due to the different nature of seamless square tube, the behavior reflected by the data is also different. The deformation and destruction process of the data under the impact of seamless rectangular tube is still elastic deformation, elastic seamless rectangular tube deformation and fracture, but the loading speed has a great influence on these three stages, especially the deformation of seamless rectangular tube. Due to the demand time for seamless rectangular tube deformation after the data is stressed, the deformation of seamless rectangular tube in the data may not be carried out in time with the increase of loading speed, which is manifested in the fall of deformation ability of seamless rectangular tube in the data and the increase of deformation resistance of micro seamless rectangular tube such as elastic limit and yield limit. Secondly, under the impact of the seamless square tube, the uneven or partial deformation of the plastic matrix of the data is more prominent than that under the static load. The deformation of the seamless square tube is likely to be limited to a small range, and it will lead to cracks and fractures here. This uneven deformation of the seamless square tube further limits the development of the deformation of the seamless square tube of the data. Therefore, in general, the impact seamless rectangular tube has a tendency to promote data embrittlement. The data with large deformation ability of seamless rectangular tube under static load may become very small and brittle under impact of seamless rectangular tube.
