Due to the increase of square tube production， there are more and more fake and shoddy square tubes in the market. How to distinguish the fake and shoddy square tubes? Let me teach you some points to distinguish the fake and shoddy square tubes.
Viewing color: the color of the cold galvanized square tube is yellowish green， cyan white or slightly colored at a fixed angle with the sun. The color of hot-dip galvanized square pipe is silver white at a fixed angle with the sun.
LiegeHigh productivity of square tube: the efficiency of cold production of mechanical parts is very high， especially for parts with large batch. Cold production can be several times， several times or even hundreds of times higher than cutting. For example， the use of cold pin for automobile is twice higher than that of cutting. At present cold pin automata is used to improve productivity. The productivity of table cooling automata is equivalent to that of ordinary lathes or shaft self-propelled machines.
Forging square tube: a kind of pressure processing in which the reciprocating impact force of the forging hammer or the pressure of the press changes the blank into the shape and size we need. It is generally divided into forging and die forging. It is often used to produce large-scale materials and materials with large square tube size.
Malheim DrurPig iron refers to the product made by smelting iron ore in blast furnace. It is mainly used for steelmaking and square casting. Put the cast pig iron in the melting furnace to obtain cast iron (liquid)， the rolling of rolling groove often exceeds the standard.
When the vehicle is replaced with seamless square tube blank and cast the liquid cast iron into a cast square pipe. This kind of cast iron is called cast iron.
The appearance of fake and inferior square tubes often has pitting. Pockmarked surface is an irregular uneven defect on the surface of square lead pipe due to serious wear of rolling groove. Due to the pursuit of profit by fake and shoddy square tube manufacturers， so as to ensure the quality of parts and avoid wrinkles.
Because the green billet can be pressed into any shape， it is easy to weld the square tube into difficult products.
The banding caused by component segregation is difficult to be eliminated by heat treatment. Generally， normalizing can reduce this segregation to a certain extent. Generally， normalizing can correct the segregation to the allowable level. If the banding is serious， it can be improved by multiple normalizing. It is reliable to conduct high-temperature diffusion annealing first and then normalize again， which can completely eliminate the strip， but the cost will be very high， which is difficult to achieve for the steel plate due to the surface quality.
For oil， the oil brush work shall be carried out in accordance with the requirements of the rule system， so as to ensure the oil brush and the oil in the correct position of the brush and avoid wrinkles.
Excellent serviceStage ( & mdash; )
For oil the oil brush work shall be carried out in accordance with the requirements of the rule system， so as to ensure the oil brush and the oil in the correct position of the brush and avoid wrinkles.
The strength， plasticity and hardness discussed above in fatigue QB are the indicators of the mechanical properties of metals under static load. In fact， many machine parts work under cyclic load， under which fatigue will occur.
special shaped square pipe is the general name of square pipes with other cross-section shapes except circular pipe. According to the different cross-section shape and size of steel pipe， it can be divided into special-shaped square pipe with equal wall thickness (code D)， special-shaped square pipe with unequal wall thickness (code BD) and special-shaped seamless steel pipe with variable diameter (code D) These special-shaped large-diameter qb square tubes are widely used in various structural parts， tools and mechanical parts. Compared with circular tubes， special-shaped tubes generally have large moment of inertia and section modulus， and have large bending and torsion resistance， which can greatly reduce the structural weight and save steel. Square tubes are an indispensable part of construction work
High valueSquare tube production most square tube processing is square tube pressure processing，Liege25mm galvanized water pipe， resulting in plastic deformation of the processed steel (billet， ingot， etc.). According to the square tube processing temperature， the square tube can be divided into cold processing and hot processing. The main processing of square tube includes: rolling: the gap (various shapes) between the square tube metal blank and the rotating roll ， because of the compression of the roll， the material section is reduced and the length is increased. This is a common production method for producing square tubes. It is mainly used to produce square tube profiles， plates and tubes. It is divided into cold rolling and hot rolling.
How to specify the yield point of square tube: if the stress decreases， the upper and lower yield points shall be distinguished. The unit of yield point is nmm (MPA). Upper yield point
Square tube nonferrous metals， also known as non-ferrous metals， refer to metals and alloys other than ferrous metals， such as copper， tin， lead， zinc， aluminum， brass， bronze，Liege63mm galvanized pipe， aluminum alloy and bearing alloy. In addition， chromium， nickel， manganese， molybdenum cobalt square tube，LiegeGalvanized square pipe， vanadium， tungsten， etc. are also used in industry. These metals are mainly used as alloy additives to improve the performance of metals. Tungsten， molybdenum， etc. are mostly used to produce cemented carbide for tools. The above non-ferrous metals are called industrial metals. In addition， there are precious metals: platinum， gold， silver and rare metals， including radioactive square tubes.
LiegeThe other is designed with deformation angle， which can be regarded as DEG from round tube to square tube; To & deg; The bending deformation of angle， so the deformation angle & theta; It can accurately reflect the deformation degree of corners and edges. In the design process， considering the influence of dimensional accuracy and metal work hardening， the distribution of deformation angle is usually larger at the beginning and middle passes， the fillet part of the pipe blank cannot be filled with the pass， so the pass perimeter is different from that of the pipe blank. In order to ensure the dimensional accuracy， the fillet part of the pass needs to be corrected and calculated. Therefore， this method has higher design accuracy than other methods. However， due to the large amount of iterative calculation， you can directly use the deformation angle & theta; Pass design.
Plasticity QB square plasticity refers to the ability of metal materials to produce plastic deformation (deformation) without deformation under load.
If the test results of square tubes fail to meet the provisions of product standards， the unqualified ones shall be selected， and double the number of samples shall be taken from the same batch of square tubes for re inspection of unqualified items. If the re inspection results (including any index required by the test of the project) are unqualified， the batch of square tubes shall not be delivered. If the following inspection items fail to pass the preliminary inspection， re inspection is not allowed: A. There are white spots in the low magnification; b. Microscopic.
