If the test results of square tubes fail to meet the provisions of product standards, 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.Stainless steel square tube for fluid transportation (gbt-) is a hot-rolled (extruded, expanded) and cold drawn (rolled) square tube made of stainless steel for fluid transportation.Halleback,Hardness test is to determine the hardness of seamless qb square pipe by slowly pressing a hard indenter on the sample surface according to the specified conditions,Halleback159 galvanized square pipe, and then testing the indentation depth or size.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.Mogilev,The pipeline is only subject to chemical pickling, which can remove oxide scale, rust and old coating. Sometimes it can be used as the reprocessing after sand blasting. Although chemical cleaning can make the surface reach a certain cleanliness and roughness, its anchor lines are shallow and easy to pollute the surrounding environment. The square tube shall be submitted for acceptance in batches, and the batch rules shall comply with the provisions of corresponding product standards.Steel used & mdash& mdash; Such as bridge steel, ship steel boiler steel, pressure vessel steel, agricultural machinery steel, etc.Square tube has a wide range of application fields. Its main field is the construction industry, which promotes the development of economic construction. Because the production process of square tube hole is different, the production design of square tube hole is also different. Next, I will introduce in detail the types of tube hole design below.

Special performance steel: A. stainless and acid resistant steel; b. Heat resistant steel: including oxidation resistant steel, heat strength steel and air valve steel; c. Electric heating alloy steel; d. Wear resistant steel; e. Low temperature steel; f. Electrical steel.The strip caused by component segregation, that is, when the steel contains harmful impurities such as phosphorus and is pressed and delayed, the impurities elongate along the rolling direction. When the steel is cooled below , these impurities become the core of ferrite, making the morphology of ferrite distributed in bands, and then pearlite distributed in bands. This band can be eliminated by electroslag remelting and increasing crystallization speed.It should be noted that the position of the disc from the calibration line can be adjusted according to the reinforcement diameter, and R and R can be equal or different.Professional is king,Hundreds of degrees Celsius, which can save energy.The advantage of empty bending is that it can bend the side length when the real bending cannot be carried out, such as synchronous bending and finishing of the upper side and side of qb square tube. Empty bend can also bend R & amp; amp; lt; .T without fracture of pipe wall.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, the rolling of rolling groove often exceeds the standard.

. fake and inferior square tubes are easy to fold. Folding is a variety of broken lines formed on the surface of square tubes and this defect often runs through the longitudinal direction of the whole product. The reason for the folding is that the fake and shoddy manufacturers pursue the rate, the reduction is too large, resulting in ears, folding occurs during the next rolling, the folded products will crack after bending,Hallebackninety-five,The second is the pickling of the square pipe. Both chemical and electrolytic methods are used when pickling the square pipe. These two methods can remove the oxide skin of the square pipe.Process flow of square tube drawing: because the size of the die hole of the square tube drawing is smaller than the outer diameter of the tube in front of the drawing, in order to make the front end of the square tube pass through the die hole smoothly, so that the clamp jaw of the drawing trolley can the head of the square tube, it is necessary to sharpen the head of the square tube before drawing. Therefore, It is generally ~ mm, and the heating temperature is between ~ ℃ according to different wall thickness. Then use ~ kg air hammer to sharpen and grind the head of the square pipe. Generally, the square pipe with diameter less than mm can be sharpened by rotary forging hammer or roll forging machine.At this time, if the welding wire of the same material is used for spot welding where the thickness is insufficient,HallebackGalvanized square pipe quick connector, it shall be welded to the fixed thickness, ground and sandblasted, and repair welding shall be adopted where there are cracks, even if the steel pipe with another large opening can be made up at one time.HallebackSquare tube is made of different materials. It needs qualified inspection by relevant staff before leaving the factory. Square tube has a wide range of uses. Its main field is not only the construction industry, but also can be seen everywhere in our daily life. The service life of square tubes is mainly affected by surface treatment. I will explain the specific operations of surface treatment of square tubes.Impact toughness the load acting on the machine part at a great speed by QB is called impact load, and the ability of metal under impact load is called impact toughness.According to metallographic classification, the annealed state of square tube: A. hypoeutectoid steel (ferrite + pearlite); b. Eutectoid steel (pearlite); c. Steel precipitation through a common square tube (pearlite + cementite); d. Ledeburite steel (pearlite + cementite).