The difference between q355b square tube and Q345A is that there are fewer impurities s and P and better low-temperature impact performance. From the welding point of view, when the impurity elements in the base metal are less, it is good for welding hot crack.
Two main factors should be considered in the design of square pipe section: one is the safety of the section; the other is the economy of the section. For the safety of the section, we require that the ratio of waist thickness to height of H-section steel should not be less than 145. For H-section steel used as column, its economy is expressed by the ratio of torsion radius to its mass.
San-Rafael.The reason why it is divided into two types is that chemical cleaning can only clean the surface very thoroughly, and it is difficult to achieve the desired results in some fine cracks.
The calculation method theory of square tube mechanics is feasible to calculate static structures, such as warehouses, houses and bridges, but it is not suitable for moving components such as wheels. At this time, people often use the plastic theory. The research of the plastic theory can be traced back to 1914. In 1975, the European Design Association formulated D plastic design code, which is mainly used for plane beams under static load and bending stress For the frame structure with stress, the requirements are as follows:% 26sigma; B% 26sigma;% 26zeta;% 26ge;% 26delta;% 26ge; 15% for high-rise buildings, more detailed calculation is required. In the case of plastic design, the allowable stress is usually calculated according to the safety factor that the allowable stress is not less than the dynamic load and multiplied by the allowable stress. In the case of bending of an axis, because the action form of load includes tension, compression, meandering shear and so on, because the strength is also divided into tensile strength, flexural strength, shear strength and so on. There is often a definite connection between various strengths. In normal use, tensile strength is often used as the fundamental strength gauge.
The common surface treatment of square pipe includes surface treatment, shot blasting treatment, manual mechanical treatment and flame treatment. The treated will be separated. 4 ~ 6Mpa compressed air entrains abrasives, and the nozzle sprays to the steel surface at high speed. The impact and friction of abrasives remove the oxide scale, rust and dirt on the steel surface and make the steel surface reach a certain roughness.
The welded joints of square pipes are subject to on-line continuous ultrasonic automatic flaw detector to ensure the NDT coverage of spiral welds. If there are defects, it will automatically alarm and spray marks. The production will adjust the process parameters at any time to eliminate the defects in time.
Therefore, Q345A is usually not preheated. However, when the plate is very thick, it should be preheated because it cools quickly. Once 20# steel was cracked by J422 welding. If the plate thickness is more than 70mm, there is a great risk of not preheating.
After chemical pickling, We only need to treat according to these, so that the square tube can bring us great help in the use process. The cold galvanized square tube is the principle of cold galvanizing on the square tube used to make the square tube have corrosion performance. Different from hot-dip galvanizing, cold galvanizing coating is mainly carried out according to the electrochemical principle. Therefore, it is necessary to ensure the sufficient of zinc powder and steel resulting in electrode potential difference,San-Rafael350 square tube, so the steel surface treatment requirements are very high.
Strictly feed Si Ca wire quantity to ensure effective & Omega in steel; When (CA) is about 0.002%, the inclusions can be fully denatured without generating more high melting point inclusions.
Test results.As for the color treatment technology of q355b square tube, the application of color q355b square tube treatment technology includes chemical method and electrochemical method from the process point of view. They can get different colors by treatment in specific electrolyte, so as to improve the wear resistance, color and variety of q355b square tube, which can be applied to different occasions and obtain different economic benefits.
In the process of square pipe, we will conduct a variety of tests on it to ensure that the square pipe can be better used in practice. In order to make better use of large-diameter steel pipe, we will continue to innovate. Let's introduce the main elements contained in the lower pipe. For the martensitic chromium square tube, the main elements affecting the are chromium, carbon and molybdenum; For Martensitic chromium nickel square tube, the main influencing elements are nickel, molybdenum, aluminum, cobalt, nitrogen and titanium.
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.
The standard quantity of combustible and nonflammable square pipes is gbt97-1 (gbt97-199). The representative material is l245-l4 pipeline steel. Professional square pipes, square rectangular pipes, galvanized square pipes and galvanized pipes are of high quality and low price. They are fire-resistant, waterproof high temperature resistant, safe and reliable. They are mainly used to transport combustible and nonflammable fluids with high requirements.
The cost is reasonable.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%.
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 30 ~, which will be oriented to the whole country for a long time Individuals and enterprises provide all kinds of square tubes, square rectangular 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.
The butt joint between the head and tail of square pipe and strip steel adopts single wire or double wire submerged arc welding, and automatic submerged arc welding is adopted for repair welding after rolling into square pipe.
San-Rafael.On the basis of thermodynamic calculation, the quality assurance of square tube, rectangular tube, seamless square tube, galvanized square tube and galvanized tube is professional. New and old customers are welcome to consult during the preferential activities. The process conditions of calcium treatment of 20CrMo sulfur-containing square tube are analyzed, and the sulfur-containing gear rolled products after calcium treatment are sampled and studied. The conclusions are as follows: in order to minimize the generation of Cao in sulfur-containing square tube steel, Omega in molten steel; (O) It must be taken off to 10 & times; The rate of calcium can only be guaranteed below 10-6.
The researcher's test before using the strip thinning drawing also confirmed that using the strip thinning drawing can greatly reduce the large value of tangential residual stress of the drawn parts and effectively prevent the occurrence of longitudinal cracking. According to different deformation degree and original sheet thickness, the appropriate thinning coefficient & psi is selected; N (generally 0.9t ~ 0.95t), if & psi; If n is too small the deformation stress will increase sharply, resulting in the fracture of the bottom of the drawing part.
The belt is sent to the metal flaw detector (or hydrostatic test) for internal flaw detection. If there are cracks, bubbles and other problems inside the steel pipe,San-RafaelHot dip galvanized rectangular pipe manufacturer, they will be detected. Steel pipes should be strictly selected manually after quality inspection. After the steel pipe is inspected, the number, specification, production batch number, etc. shall be sprayed with paint. And hoisted into the warehouse by crane.