Seamless square tube fixed-length processing

Seamless square pipe is a title for square pipe and rectangular pipe, that is, steel pipe with flat side length. It is made by rolling strip steel through skill disposal. Usually, the strip steel is unpacked, flattened, bent and welded to form a round pipe, which is then rolled into a square pipe and then cut into the required length.

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Steel prices: new highs, when to top?

Today's rebar 1805 opened upward, the highest intraday 4104, closed at 4056, up 79 or 1.99 percent; hot coil closed at 4074, up 98 or 2.46 percent; and iron ore soared nearly 5 percent, behind the 0.64 billion of capital blessing, thread followed by 0.58 billion funds. Today, the billet market continued to rise over the weekend, with some manufacturers rising by 30 yuan/ton to 3970 yuan/ton (including tax cash leaving the factory), and recently billets have repeatedly reached new highs this year. It is understood that the straight hair of billets is acceptable at the beginning of the morning, and there is a transaction in 4020 yuan/ton from stock. After the intraday increase of 30 yuan/ton, the mentality of merchants is boosted, and some of them are smooth.

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How about the impact resistance of seamless square tube

Seamless square tube for the power supply as a leading agent of a component, high solid fraction of architectural coatings. Sub-primer and topcoat. A component consists of epoxy resin glue, color paste and filler, modifier.

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Key characteristics of seamless rectangular tubes

Seamless rectangular tube has excellent compressive strength, ductility, plastic deformation, welding and other performance, with excellent ductility, its aluminum alloy layer and steel base strong connection, can carry out cold extrusion, cold rolling, etc., with excellent compressive strength, ductility, plastic deformation, welding and other performance. Have excellent plasticity. Cable bending and other forming does not destroy the coating, suitable for general production and processing, such as drilling, laser cutting, welding, cold drawing and other processing technology. Key characteristics associated with seamless rectangular tubes: 1. anti-rust treatment, anti-corrosion-dip zinc layer, zinc-rich phosphating treatment layer, electrostatic induction coating all have excellent anti-rust treatment effect. Seamless square tubes are generally able to ensure that they do not rust for thirty years in extreme natural environments. 2. strongly weathered electrostatic powder spraying process uses solid powder to condense at high temperatures, which is very stable for liquid architectural coatings containing architectural coatings. Therefore, the seamless square tube has excellent anti-ultraviolet light maintenance function, and is not easy to fade under long-term sunlight irradiation. 3. anti-disassembly: the application of anti-disassembly parts installation, anti-disassembly parts and pipelines are tested by China's technical units, all kinds of index values are beyond the national industry standards. Because of the necessity of office environment, most of the plates of galvanized square rectangular tubes are hot-dip galvanized outside the rectangular square tubes, which further improves the anti-corrosion characteristics. In order to better ensure the welding quality, the hot-dip galvanized layer on the surface of the galvanized steel pipe should be removed during welding. In order to better remove the whitening of the hot dip galvanized layer in the welding and heat affected zone, to ensure the welding quality and the excellent working standards of the staff. Naturally, the seamless square pipe welded in this way is only used in the general office environment, and it is not suitable to work in the corrosive natural environment.

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Method of eliminating banded structure of seamless rectangular tube

The banded structure makes the part anisotropic, which reduces the elongation, area shrinkage and impact toughness values in the direction perpendicular to the banded structure. Banded tissue serious parts, heat treatment is easy to produce deformation, the same part of the hardness is not uniform, low carbon content of the parts of the quenching soft point. The reason for the formation of banded structure is the segregation of alloying elements in steel, especially the segregation of sulfur and phosphorus and various non-metallic inclusions, such as MnS and silicate inclusions, which are easy to form banded structure. The dendrite segregation produced during solidification of steel can not be eliminated in the later pressure processing process, which often keeps the banded structure. In addition, the hot tie and forging process is improper, especially without repeated forging, change direction flip forging, will also make the raw material banded structure preserved. The specific elimination methods of seamless rectangular tube are as follows: (1) The banded structure caused by component segregation, that is, when the steel contains harmful impurities such as phosphorus and is pressed, the impurities stretch along the rolling direction. When the steel is cooled to less than 4, these impurities become the core of ferrite so that the ferrite morphology is banded, and then the pearlite is banded. This banded structure can be eliminated by electroslag remelting and increasing the crystallization rate. (2) Banded structure caused by improper hot working temperature, I .e. when the hot working stop forging temperature is in the two-phase zone (between/4, and 40), ferrite is precipitated from austenite in a banded form along the metal flow direction, austenite that has not yet decomposed is cut into banded form, and when cooled to A,, banded austenite is transformed into banded pearlite. This structure can be improved or eliminated by increasing the final rolling temperature, increasing the forging ratio or diffusion annealing and normalizing. (3) The banded structure caused by component segregation is difficult to eliminate by heat treatment. This segregation is usually mitigated to some extent by normalizing, which normally corrects the segregation to an allowable level. If the banded tissue is serious, it can be improved by normalizing many times. The most reliable method is the first high-temperature diffusion annealing, followed by a normalizing, which can achieve the effect of completely eliminating the banded structure, but the cost will be very high, for the steel plate is limited by the surface quality, it is difficult to achieve.

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How to prevent deformation of seamless square tube

Seamless square tubes bear different load forms, and the degree of tightness of bearing fit should also be different. When bearing a fixed load, the fit should be looser to make the bearing more convenient to assemble and disassemble mechanically, but not too loose, otherwise it will cause Sliding on the mating parts will wear the mating surface. Therefore, transition fit or clearance fit with very little clearance should be generally selected. When the seamless square tube is subjected to a rotating load, a tighter fit should be selected to prevent the ferrule from sliding on the mating parts and cause wear on the mating surface, but the interference should not be too large, otherwise the internal clearance of the bearing will be reduced. Even disappear completely, excessive contact stress is generated, which leads to accelerated shaft wear and affects its service life. When the seamless square tube bears the swing load, the degree of tightness of the fit is generally the same as that of the seamless square tube when it bears the rotation load, or slightly tighter.

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