C. special performance steel: (a) stainless and acid resistant steel; (b) Heat resistant steel; (c) Electric heating alloy steel; (d) Electrical steel; (e) High manganese wear resistant steel.Plasticity QB square plasticity refers to the ability of metal materials to produce plastic deformation (deformation) without deformation under load.Trondheim,Elongation after square tube breaking (& sigma;): in the tensile test the percentage of the length increased by the gauge length of the sample after breaking and the length of the original gauge length is called elongation. In & sigma; Expressed in%.Mechanical engineering, power plants, agricultural and chemical machinery, glass curtain walls, automobile chassis, airports, boiler construction, highway railings, housing construction, pressure vessels, oil storage tanks, bridges, power station equipment, heavy transportation machinery and other welded structural parts with high load, etc. Process classification: according to the production process, square tubes are divided into hot-rolled seamless square tubes, cold drawn seamless square tubes, seamless square tubes and qb square tubes.Baraki,The characteristics of square pipe are as follows: the production process of square pipe is simple, the production efficiency is high the cost is low and the development is fast. The strength of spiral square pipe is generally higher than that of straight seam square pipe. It can produce square pipe with larger pipe diameter with narrow blank, and square pipe with different pipe diameter with blank of the same width. However, compared with straight seam pipe of the same length, the weld length is increased by ~, which will be oriented to the whole country for a long time Individuals and enterprises provide all kinds of square tubes, seamless square tubes, galvanized square tubes, galvanized tubes,TrondheimGalvanized square pipe and rectangular pipe, on-site settlement, honest operation, local offices,Trondheim60 galvanized square pipe, long-term cooperation, and low production speed. Therefore, most of the smaller square tubes adopt straight seam welding, and most of the large-diameter square tubes adopt spiral welding.Main uses of square tube: square tube is mainly used in tap water engineering, chemical industry, electric power industry, agricultural irrigation and urban construction. It is one of the key products developed.Classification of square tube steel is iron carbon alloy with carbon content of square tube between .% - %. In order to ensure its toughness and plasticity, the carbon content generally does not exceed %. In addition to iron and carbon, the main elements of steel also include silicon, manganese, sulfur, phosphorus, etc. There are various classifications of steel and square tubes, mainly including the following: square tubes are classified into ordinary steel according to quality (P & le; .%, S & le; .%)

. 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, and the strength of the square tube will be greatly reduced.In fact, 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.There are many ways of ignition, such as arc, electric spark, flame strong current, high-temperature furnace, electron beam, laser, high-temperature radiation, microwave, chemical furnace, etc.Standard requirements,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.Brinell hardness (HB), Rockwell hardness (HRC) and Vickers hardness (HV) are commonly used.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).

Hardness QB square hardness is a pointer to measure the hardness and softness of metal materials. At present, the hardness method is commonly used to measure the hardness in production. It uses the indenter with fixed geometry to measure the hardness value of the metal material surface tested under fixed load according to the degree of hardness.Range,The inspection items, sampling quantity, sampling position and test of square tube shall be in accordance with the provisions of corresponding product standards. With the consent of the demander, hot-rolled square tubes can be sampled in batches according to the rolled root array.The cutting surface of the square tube shall be true circle, and the cutting line shall be at right angles to the axis of the square tube. Excessive force is the reason for cutting the square tube into flat or oval, so the square tube should be cut with appropriate force.Hot dip galvanized square tube is a kind of square tube which is welded after using steel plate or steel strip to curl and form, and on the basis of this square tube, the square tube is placed in the hot dip galvanized pool and formed through a series of chemical reactions; The production process of hot-dip galvanized square pipe is relatively simple, but the production efficiency is very high and there are many specifications and varieties, but this kind of square pipe needs little equipment and capital, which is more suitable for the production of small galvanized square pipe manufacturers.Trondheim, the cost is low and the development is fast. The strength of spiral square pipe is generally higher than that of straight seam square pipe. It can produce square pipe with larger pipe diameter with narrow blank the production efficiency is high, and square pipe with different pipe diameter with blank of the same width. However, compared with straight seam pipe of the same length, the weld length is increased by ~, which will be oriented to the whole country for a long time Individuals and enterprises provide all kinds of square tubes, seamless square tubes, galvanized square tubes, galvanized tubes, on-site settlement, honest operation, local offices, long-term cooperation, and low production speed. Therefore, most of the smaller square tubes adopt straight seam welding, and most of the large-diameter square tubes adopt spiral welding.Strength QB square strength refers to the performance of metal materials under static load (excessive plastic deformation or fracture). Since the action modes of load include tension, the strength is also divided into tensile strength bending and shear,Trondheim20 price of galvanized square pipe, flexural strength and shear strength. There is often a certain between various strengths. Generally, tensile strength is used as the basic strength indicator. Precision pipe is a seamless pipe with high dimensional accuracy and good surface finish for mechanical structure and hydraulic equipment. The selection of precision seamless mechanical structure or hydraulic equipment can greatly save machining hours, improve material rate and improve product quality. Seamless pipe is rolled in the annular pass composed of variable cross-section circular hole groove and fixed conical plug. Cold drawing is usually carried out on single chain or double chain cold drawing machine. This method is to put the heated pipe blank in a closed cylinder, and the perforated rod and rod move to extrude the part from the smaller die hole. This method can produce steel pipe with smaller diameter.B. spring steel C. bearing steel tool steel: A. carbon tool steel; b. Alloy tool steel; c. High speed tool steel.