steel tube

　　Welded pipe is generally divided into straight seam welded pipe and spiral welded pipe two types. 　　 Strength characteristics 　　When the pressure in the pipe withstand, usually two main stress on the wall, that the radial and axial stress stress δ. Synthetic weld stress δ, where α is the helix angle of the spiral weld pipe. Spiral welded seam degree helix angle is generally so synthetic, and spiral weld Longitudinal stress is the main stress. Under the same operating pressure, spiral pipe of the same diameter than the Longitudinal wall thickness can be reduced. 　 　Hydrostatic burst strength 　　By the relevant comparison test to verify the spiral welded pipe and Longitudinal yield pressure and burst pressure measured and theoretical values ??match, the deviation closer. But whether it is the yield stress or burst pressure, were lower than the Longitudinal spiral welded. Burst test also shows that the rate of deformation ring spiral welded pipe bursting Longitudinal significant...

　　The solution temperature is mainly determined by chemical composition. In general, the solution temperature should increase for those containing many kinds of alloy elements or with high alloy. Especially for those that contains high steel, like manganese, molybdenum, nickel, silicon. Only by increasing the solution temperature can we dissolve and soften them. But for stabilized steels such as 321 stainless steel pipe , when the solution temperature is high, the carbide of the stabilizing elements are fully dissolved in the austenite and precipitate in the grain boundary with the form of Cr23C6 after cooling. That can cause intergranular corrosion. We often adopt the lowest solution temperature for carbide(Tic and NbC) of the stabilizing elements which can't be dissolved or treated by solid solution. 　　For seamless stainless steel pipe, the three elements of the solution treatment are temperature, holding time and cooling rate. What is the role of solution treatment of seamless...

　　We know that steel pipe surface treatment is one of the key factors determine the service life of the pipeline corrosion, it is a precondition for whether the anti-corrosion layer and steel tube can be combined. It is verified by the research institutions that the life of the coating depends on the quality of coating types, coating quality and environmental factors such as construction. The steel tube surface treatment effects on coating life accounted for about 50%, therefore, we should be strictly accordance with the specification on the coating on the surface of steel pipe requirements, continuously explore and summary, continuously improve steel pipe surface treatment. 　 　1. Cleaning 　　Using solvent and emulsion to clean the steel surface, to remove oil, grease, dirt, lubricants, and similar organic matters, but it cannot remove rust, scale, such as welding flux on the surface of the steel, so only as auxiliary in the anti-corrosion production. 　 　2. Rust cleaning by tools ...

　　Transverse cracks will affect the finished product rate just after rolling. Increase billet cleanup time, both great harm. The slab temperature is brittle zone of 700-900 ℃. The reason the lower surface cracks is 1050-1100 ℃, transverse cracks on the surface of the reason is the billet surface by a large segment straightening straightening stress. Niobium nitride in the austenite grain boundaries reduces the binding force, the grain boundary precipitation. At this point in the curved section slab junction arc poor, resulting in a lower surface cracks. Vertical cracks and chemical composition, mold cooling water temperature, mold equipment, the chemical composition of the slag, continuous casting machine precision secondary cooling system related. Related prevention measures: 　　1. Control steel composition. Try to prevent wC is 0.12% -0.16% D36 steel carbon content in the smelting process control method according to the upper limit. Can effectively reduce the cracks. Peritectic reac...

　　Seamless steel tube is the combination of machining and metal pressure processing, processing many ways, within the scope of machining and the like, are common stamping, forging method, roller processing method, rolling method, bulging method, stretching , bending method, and a combination of processing methods, to understand in detail below under: 　　1, Bulging method: one is placed in the seamless steel pipe rubber, with the top punch compression, so that the sub-convex shaped seamless steel pipe; Another method is forming a hydraulic bulging in the middle of seamless steel tubes filled with liquid child, by fluid pressure seamless steel sub-drum into the desired shape, like we used corrugated seamless steel pipe production is most used in this way. 　　2, Forging method: using a swaging machine seamless steel pipe end or part of the child to be rushed stretch, reducing the outer diameter, often have a rotary swaging machine, link type, roller. 　　3, Roller method: Place the cor...

　　High-pressure alloy pipe deformation strengthening is using the method of deformation of steel reinforcement. Also known as the strain hardening or work hardening. The strength of the material at the macro (or a whole) the ability to resist deformation (or flow stress). Hardness is the ability of the material to resist plastic deformation localized (whether micro-hardness, Vickers hardness, Rockwell hardness or Brinell hardness). Both have similar corresponding relationship in many cases. Strength of the material, the greater the resistance to plastic deformation, the higher the hardness value. Conversely, the higher the hardness of the material, the material may be due to increased brittleness, its strength is not fully reflected in such strength index value is not high. 　　For longer subjected to heat treatment, and the use of the material in temperatures well below the recrystallization temperature of the high-pressure alloy pipe steel pipe material (such as low-carbon low-alloy...

　　Seamless precision steel pipe products have problems of uneven eccentric thickness, but what are the reasons? Many people don’t understand, today we will talk about how to produce eccentricity of seamless steel pipes such as cold drawn steel pipes, cold rolled steel pipes and hot rolled steel pipes. Rate, why the concentricity of seamless steel pipes is not so ideal? Eccentric steel pipes are the most easily produced in the production of hot rolled steel pipes, and most of the connecting rods are produced during the hot perforation process. 　　Through the anatomical analysis of the steel pipe after the automatic pipe rolling machine, it is considered that the vertical and horizontal wall thickness distribution of the perforated pipe after the automatic pipe rolling machine is rolled unevenly, and the characteristics of the perforated pipe are basically maintained. The wall thickness of the perforated pipe is unevenly distributed, that is, the pipe wall still has a spiral wall thickn...