Section shape classification of large-diameter qb square tube square tube is classified according to section shape: simple section square tube & mdash& mdash; Square tube， open square pipe， corrugated square pipe， special-shaped square pipe， large-diameter qb square pipe surface treatment classification square pipe is divided according to surface treatment: hot-dip galvanized square pipe， electro galvanized square pipe， oil coated square pipe， acid pickling square pipe， machine tool equipment， machinery industry， chemical industry， steel structure， shipbuilding， automobile， steel beam and column， special purpose， large-diameter qb square tube wall thickness classification， large-diameter qb square tube according to wall thickness Classification & mdash& mdash; Super large diameter qb square pipe， large diameter qb square pipe and thin-wall large diameter qb square pipe rectangular pipe are the names of square pipe and QB square pipe， that is， steel pipe with equal side length. It is made of rolled strip steel after process treatment. Generally， the strip steel is unpacked， leveled， crimped and welded to form a round pipe， then rolled into a square pipe from the round pipe， and then cut into the required length. Usually pieces per bag. Qb square pipe， also known as square and rectangular cold-formed hollow section steel， is referred to as square pipe and rectangular pipe， code f and j respectively. The allowable deviation of wall thickness of qb square pipe shall not exceed plus or minus % of nominal wall thickness when the wall thickness is not greater than mm， plus or minus % of wall thickness when the wall thickness is greater than mm， except for the wall thickness of corner and welding joint area.
The general delivery length of qb square pipe is mm-mm， mostly mm and mm. Qb square tube is allowed to deliver short length and non fixed length products not less than mm， or in the form of interface tube
DandmondFrom the perspective of production， we should give full play to the productivity of production equipment and reduce the consumption of fuel and equipment on the basis of meeting the size and performance requirements of qb square tube. Therefore， the temperature of no open forging and final forging is a comprehensive technical and economic problem. If qualified qb square tubes can be obtained in the temperature range of the vehicle， reasonable process procedures should be selected from an economic point of view. Obviously， the higher the temperature， the easier the forging and the higher the productivity， but the greater the fuel consumption and the loss of the heating furnace; We should consider these two aspects and make a reasonable choice.
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.
ToledoHot dip galvanized square pipe is widely used， mainly in curtain wall， solar power generation support， construction， machinery and steel structure engineering， machinery and construction. The effect of cold galvanized square tube is far from that of hot galvanized square tube; How to distinguish hot galvanized square pipe from cold galvanized square pipe?
Superior square tubular steel (both P and s ≤ .%)
After spraying (throwing) derusting， it can not only expand the physical adsorption on the pipe surface， but also enhance the mechanical adhesion between the layer and the pipe surface. Therefore， spray (throwing) derusting is an ideal derusting method for pipelines. Generally speaking， shot blasting (sand) is mainly used for the inner surface treatment of the pipe， and shot blasting (sand) is mainly used for the outer surface treatment of the pipe. Several problems should be paid attention to in derusting by spraying (throwing).
Generally， chemical and electrolytic methods are used
The standard number of spiral square pipe (standard of the Ministry of petroleum) for low pressure transmission is syt-. The representative materials are qbqb and other carbon steel materials. It is mainly used for low-pressure transmission of water， oil， natural gas， heating and other pipelines.
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.
TrustworthyPut the pig iron for steelmaking into the steelmaking furnace according to the specified process to obtain steel. The products of steel include ingots， continuous casting billets and various steel castings made of straight square tubes. Generally speaking， steel refers to the steel rolled into various square tubes. Square tube steel belongs to ferrous metal but steel is not completely equal to ferrous metal.
The reason why it is divided into two types is that chemical cleaning can only clean the surface very thoroughly， many mechanical machines are under repeated load， and the whole opportunity is tired in this environment.
Welding is a synthetic gradient material， which can be used as solder to weld special-shaped materials in order to overcome the mismatch of chemical， the casting cleaning is not just shot blasting. For large parts， the drum sand cleaning is carried out first， that is， the riser of the casting is cut off and rolled in the drum， and the square tubes collide with each other in the drum to remove most of the sand on the surface before shot blasting or shot blasting.
Principle of cold drawing strengthening: the lattice defects of steel increase during plastic deformation， and the serious distortion of defect lattice will hinder the progress and slip of lattice， so the yield point of steel increases and the plasticity and toughness decrease. Due to the internal stress in plastic deformation，DandmondPrice of 80% galvanized square pipe，DandmondGalvanized steel square pipe factory， the modulus of steel decreases. The cold drawn reinforcement is stored at room temperature for ~ d or heated to ~ ℃ and maintained for a fixed time. This process is called aging treatment.
DandmondFor transportation: water supply， drainage， sewage treatment engineering， mud transportation， marine water transportation.
Functional index analysis of qb square tube - the load on the machine parts due to the great progress of strength is called the frontal collapse load. The power of destruction of qb square tube under the frontal collapse load is called the frontal collapse toughness.
Large diameter qb square tube production standard classification square tube is divided according to production standard: national standard square tube Japanese standard square tube， British standard square tube American standard square tube， European standard square tube and non-standard square tube.