A. square tube structural steel: (a) high quality carbon structural steel; (b) Alloy structural steel; (c) Spring steel; (d) Easy cutting steel; (e) Bearing steel; (f) High quality structural steel for specific purposes.The square tube is divided into a. boiling steel according to the degree of deoxidation and pouring; b. Semi killed steel; c. Killed steel; d. Special killed steel. The deformation of qb square tube is mainly caused by the shrinkage force of the weld greater than the strength of the base metal.Nacom,Solid bending, as the name suggests, is to compact the bending. During real bending, the inner and outer rollers and the inner and outer walls of the pipe blank are compacted in both directions.The disadvantage of empty bending is that when the upper side and side are synchronously empty bending, the forming force is easy to exceed the critical point due to the pressure generated by the upper roll and the lower roll at the same time, resulting in edge instability and concave, and will also affect the stable operation and forming quality of the unit. This is also the different characteristics of qb square tube and round tube empty bending. The concept of square tube: square tube is the pressure processing of ingot, billet or square tube Make materials of all shapes, sizes and properties we need.Asykata,The reason why the surface of fake and shoddy materials is easy to crack is that its blank is adobe with many air holes. During the cooling process, the adobe has cracks due to the action of thermal stress, and there are cracks after rolling.Square 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.Steel used & mdash& mdash; Such as bridge steel, ship steel, boiler steel pressure vessel steel, agricultural machinery steel, etc.

Alloy steel: A. low alloy steel (total alloy element content & le; %); b. Medium alloy steel (total alloy element content > ~ %); c. High alloy steel (total alloy element content > %).High strength structural steel with carbon content of .% - .%, adding main alloy elements such as manganese,NacomHot dip galvanized seamless steel pipe for inner and outer wall, silicon, niobium and titanium; Its total alloy content is %. According to the strength, it is divided into four levels: , and MPa.The principle of straightening machine is that a disc is divided into two sides to clamp round steel straight lines. Professional square tube, square rectangular tube,NacomHot dip galvanized plastic coated steel pipe, seamless square tube, galvanized square tube, galvanized tube high price, service, on-site settlement, honest operation! The edge is one with radius r, and the other outer edge must be two equal diameters with radius R. The diameter of the reinforcement to be straightened is D,Square tube structural steel A. mechanical steel: (a) quenched and tempered structural steel; (b) Surface hardening structural steel: including carburized steel, ammoniated steel and surface quenching steel; (c) Easy to cut structural steel; (d) Steel for cold plastic forming: including steel for cold stamping and steel for cold heading.Hardness 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.Change to square pipe: 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. Stage ( & mdash; )

B. low alloy structural steel C. ordinary structural steel and high-quality steel for specific purposes (including high-quality steel)Information recommendation,Normalized: A. pearlite steel; b. Bainitic steel; c. Martensitic steel; d. Austenitic steel.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 bending can also bend the inner corner of r.t without fracture of pipe wall. The disadvantage of empty bending is that when the upper side and side are synchronous empty bending, due to the pressure generated by the upper roll and the lower roll at the same time, the forming force is easy to exceed the critical point, resulting in edge instability and concave, and will also affect the stable operation of the unit and forming quality. This is also the different characteristics of qb square tube and round tube empty bending.Square tube, modified square tube, square tube QB square tube and hot-rolled square tube are qualified in quality inspection. The manufacturer adopts advanced equipment to ensure the quality of each product. Magnetic flux leakage testing for surface defects of square tubes is very similar to magnetic particle testing for square tubes, and its scope of application, sensitivity and reliability are stronger than magnetic particle testing. Indirect square forming process the traditional forming process of cold-formed square pipe is to gradually roll the hot-rolled steel coil multi stand forming unit into round pipe at room temperature, and then the shaping unit will roll the round pipe into square pipe which is called indirect square forming process. The traditional roll forming process uses the method of fixed bending point position and variable bending radian to complete the corner forming of pipe blank, which is suitable for rolling small and medium-sized products. Rolling with this process & ldquo; Superb & rdquo; Square tube will show its inherent defects. Because the roll work in the bending process of this process is always concentrated at the point, excessive stress concentration often shows microcracks in the bending process of profiles, which will lead to cracking in serious cases. The products with such defects have serious consequences when they are used in building steel structures. The study of the broken square tube column in the Hanshin earthquake in Japan shows that the corner microcrack is the main cause of the square tube fracture. At the same time, due to the different forming bending radians of products with different wall thickness, the universality of rolls is limited. The large-size cold-formed square tube used in the process adopts the advanced & ldquo; Direct Square & rdquo; The production process is to directly roll the hot-rolled steel coil into a square and rectangular shape at room temperature.Nacom,Welding seamless welding seamless is to make welded elbows. After grinding and pickling, sand blasting, there is no sign of welding on the surface. Even using advanced flaw detection equipment, it can not be seen that they are welded elbows.Comprehensive classification ordinary steel A. carbon structural steel: (a) Q (b) Q (b); (c) Q( C)； (d) Q( B)； (e) Q.Steel used & mdash& mdash; Such as bridge steel, ship steel, pressure vessel steel, agricultural machinery steel, etc.