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Now the production technology of stainless steel welded pipe is relatively perfect. It has replaced seamless steel pipes in many aspects, such as petroleum, automobile, paper making, air conditioning and so on, and its price is less than 1/5 of seamless pipe. The market demand of stainless steel seamless pipe is mainly manifested in basic industries, including oil, chemical, power generation and so on, which account for 1/3 of the total consumption of stainless steel seamless pipes. But more producers choose stainless steel welded steel pipe in addition to its cheaper price, but also mainly its own characteristics and advantages. First, look at the manufacturing process of small caliber stainless steel welded pipe, the sequence is stainless steel plate, strip, forming, melting, bright solution treatment, internal and external weld treatment, eddy current testing, laser diameter measurement, straightening and storage. Through the production process, it can be seen that the stainless steel welded pipe is continuous online production. The thicker the wall thickness is, the higher the investment of the unit and the melting equipment will be. The lower the economy and practicability of the stainless steel welded pipe is. The wall thickness of the thinner, the input-output ratio will decrease, and the product process also affects its advantages and disadvantages, usually welded pipe with higher precision and more uniform wall thickness, stainless steel pipe fittings inner surface of high brightness (steel plate surface surface brightness level decision), can be arbitrarily set foot. So it shows its economy and beauty in the use of high – precision, medium and low – pressure fluid. Let’s take a look at the manufacturing process of seamless steel pipe. The sequence is smelting, ingot, rolling, sawing, peeling, perforating, annealing, pickling, up ash, cold drawing, cutting, pickling and final storage. In addition to that of thick wall and high strength mechanical timber structure advantages, low common seamless steel pipe precision, uneven thickness, the appearance of low brightness pipe length high cost, and the appearance of pitting and black spots is not easy to remove. The following is the contrast between the two more clearly, first look at the coverage, stainless steel seamless pipe can do small diameter thick wall and large diameter thick wall, but generally they are affected by the length limit; but the stainless steel pipe wall thickness is thinner can do, can do with large diameter and small wall thickness and small diameter and small wall thick, theoretically, stainless steel coil pipe with long, how long can do. In other words, the thicker the more suitable for the use of seamless pipe, the thinner the more suitable for the use of welded pipe. The second is the average and concentricity of the pipe wall thickness. In this respect, the stainless steel welded pipe is better than the stainless steel seamless pipe. Because the plate thickness tolerance of the cold rolled plate is more average, the deformation is average during the molding process. The seamless pipe rolling process is influenced by the equipment precision and other factors, and there is a problem of uneven thickness and concentricity, but the roundness is better than that of the welded pipe. The other is the performance, the average quality of stainless steel welded pipe, appearance quality, expansion pipe performance, bending, pier head performance are better. Because the average performance of the cold rolled plate is better than that of the pipe, and the welded pipe is generally on line solution, and the heat treatment is more average, and the performance is more stable. The stainless steel seamless pipe is sampled at different positions on the same pipe, and the performance will be different. In addition, the price is the price, the price of stainless steel welded pipe is cheaper. In the end, the bearing capacity of the stainless steel seamless pipe is slightly higher than that of the welded pipe under the same specification. But the stainless steel welded pipe is formed because of the stainless steel sheet which is used, the processing is relatively simple, so the delivery time is shorter. Stainless steel seamless pipe should start from round steel, perforated and then draw cold drawn and cold rolled many times, and then produce products after solid solution annealing and acid washing. The production cycle is longer. To sum up, the application of stainless steel welded pipe is more obvious than that of stainless steel seamless pipe, of course it is under the premise of selecting high quality and qualified stainless steel welded pipe. Source: China Stainless Steel Pipe Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

The main local corrosion forms of stainless steel pipes include intergranular corrosion and point corrosion two. What are the reasons for their formation? How can the corrosion be avoided effectively? The following will be described in detail. Intergranular corrosion of stainless steel pipe The preferential corrosion is along the grain boundary. This is one of the most common forms of local corrosion. But now it is decreasing. Sensitized intergranular corrosion is due to the stainless steel pipe by 450 ~ 850 DEG C temperature sensitization (post weld heat affected zone), along the steel grain boundary will precipitate chromium carbides, which can lead to grain boundary chromium depletion. Even if the ultra-low carbon stainless steel containing 0.03% carbon is used, it will lead to chromium depletion if it stays for a long time at the sensitive temperature. This effect is the same as that of the previous alloy elements. The solid-state intergranular corrosion is due to the segregation of silicon, phosphorus, sulfur and other elements in the crystal boundary of the stainless steel pipe. The corrosion form of chromium nickel austenitic stainless steel is easily produced in the high temperature and high pressure urea plant in the HNO3 containing Cr6+. How to prevent the intergranular corrosion? The first thing to do is to select ultra-low carbon stainless steel with carbon content below 0.03% when welding purposes, but also to avoid staying at a long time at the temperature of sensitization. If conditions are available, it can also choose the brand whose carbon is less than 0.02%. Use of various kinds of stainless steel containing the stabilizing elements of titanium, niobium, such as 0Cr18Ni11Ti, 0Cr18Ni11Nb and so on. For the environment that is easy to form solid intercrystalline corrosion, urea class, nitric acid grade stainless steel and so on can be used. In addition to the necessary welding process, the stainless steel material should be prevented from sensitizing temperature during the manufacture and processing of stainless steel. Corrosion phenomenon of stainless steel pipe point Most of the corrosion is produced at a certain point on the surface of stainless steel pipeline, and then penetrates further and deeper. The pitting on the outer surface of the stainless steel pipeline is generated by using the process. Pitting corrosion of stainless steel pipes are usually shown in aqueous solutions containing halogen ions, such as Cl-, Br-, F- and so on. Point corrosion is caused by the destruction of the passivation film on the weak part of the passivation film on the surface of the stainless steel pipe. If the surface of the stainless steel contains iron particles, dust and dirt and other attachments, and the inclusions of MnS and some other intermetallic compounds, pitting can also be formed. The corrosion prevention measures, need to pay attention to regular cleaning and maintenance of stainless steel pipe surface; improving steel purity, reducing manganese and sulfur content of nonmetallic inclusions, using the pitting resistance equivalent value of high stainless steel pipe is high chromium molybdenum and chromium, molybdenum, high nitrogen stainless steel. In the sea water containing Cl- and who is medium, increase flow rate is larger than 1.5m/s, stainless steel pipe surface attachment to avoid sediment and sea creatures. Source: China Stainless Steel Pipe Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

When cutting stainless steel pipe or the groove is easy to produce defects, because of the use of oxygen acetylene flame cutting speed is too fast, or when heated, or placed directly on coke three through holes with oxygen acetylene flame, or reducers site fell system, which will directly lead to problems in the use of stainless steel pipe. So what are the detailed causes of the above problems? Through actual analysis, if the stainless steel pipe is cut or opened by oxygen block flame, it will also form chromium oxide with high melting point. It is difficult to cut off and the open hole forming is not good. The second is that the cutting speed of the bevel is too fast to destroy the tool. Third is that the stainless steel pipe after heating directly to the coke will lead to carbon increase. In addition, the field wrestling of the pipe will also be heated, which will directly affect the use of the stainless steel pipe. It is because of the high toughness and hardness of stainless steel and the tendency to form a cold hard place in the area of cutting. Therefore, the stainless steel pipe does not use oxygen acetylene flame for cutting, preventing the formation of refractory chromium oxide. When the stainless steel pipe to be processed into pipe, usually use heat can also use cold Mie Mie, tubular. For MIE bending pipe material to be the same, and straight pipe installed, and can not use the negative tolerance of pipe bending mie. Because the stainless steel pipe heat Mie temperature control requires high heat after heat treatment of Mie to do so, not hot Mie law to be applicable in small diameter stainless steel tube. Small diameter stainless steel tube was surprised mostly in the flame bending machine, bending radius should not be less than 3.5 times the diameter of the. When a small diameter stainless steel pipe is used in cold bending, the pipe is usually carried out on a manual or electric or hydraulic pipe bending machine. In order to reduce the ellipticity of the bend, the pipe should also be sands in the pipe and then bend when the pipe is bent. In addition the stainless steel pipe groove requirements the main points, the first is to use the electric stainless steel pipe beveling machine, manual for groove processing machinery for cutting speed; stainless steel pipes usually made of carbon steel 40%-60% tools have made of high-speed steel or hard alloy steel; stainless steel pipe should be made in the hole, usually is drilling with drilling machine, milling machine, boring machine etc.. Source: China Stainless Steel Pipe Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

How is the stainless steel pipe produced? Simply speaking, it is to pierced stainless steel ingots or stainless steel solid billets to form capillary pipes, and then to make them by hot rolling, cold rolling or cold dialing. There are mainly three kinds of hardness of stainless steel pipes. This paper will introduce them. Rockwell hardness The Rockwell hardness test of stainless steel pipe is the same as that of Brinell hardness test, all of which are indentation test. The difference is, Rockwell hardness testing method is to measure the depth of the indentation, this is a kind of method uses a lot of current, in which HRC stainless steel pipe standard application after HB Brinell hardness, Rockwell hardness can be applied to the determination of metal materials from soft to hard, this method makes up the deficiency of Brinell hardness method the detection method is more convenient than the Brinell hardness machine, can be directly read out from the dial hardness. However, because the smaller indentation variant of the method, so the accuracy is worse than that of Brinell hardness method. Brinell hardness In the standard of stainless steel pipe, Brinell hardness is the most widely used. Usually, indentation diameter is used to explain the hardness of testing materials, which is not only intuitive and convenient, but not suitable for hard or thin steel pipes. Vickers hardness Vivtorinox is also an indentation hardness test detection method can be used to detect metal thin layer and surface hardness, including Brinell and Rockwell two methods advantages, and also remove the basic shortcomings of the two, but the defect is not Rockwell convenient, Vivtorinox detection method in the application of the standard stainless steel pipe many. So many methods of hardness testing are said, and then the specific testing of the stainless steel is described in detail. When the inner diameter of the stainless steel pipe is above 6.0mm, the annealed stainless steel pipe under the wall thickness of 13mm can be used W-B75 type Wechsler hardness tester. Its detection is fast and convenient. It is suitable for fast and nondestructive testing of stainless steel pipes. Stainless steel pipe with inner diameter of stainless steel pipe is higher than 30mm, and the wall thickness is more than 1.2mm. The hardness of HRB and HRC is tested by Rockwell hardness tester. Stainless steel pipe diameter greater than 30mm, wall thickness less than 1.2mm stainless steel pipe, using surface Rockwell hardness test HRT or HRN hardness, diameter less than 0mm, more than 4.8mm stainless steel pipe, the pipe Rockwell hardness test the hardness of HR15T stainless steel, when the pipe diameter is more than 26mm, can also use Rockwell or surface Rockwell hardness test stainless steel wall. Source: China Stainless Steel Pipe Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

What is stainless steel pitting? To understand this concept, we must first understand the excellent corrosion resistance principle of stainless steel. In fact, it is because there is an invisible but compact oxidation protective film on the surface of the stainless steel plate, which makes the stainless steel material in the passivation state at all times. The formation of this film is due to the corresponding chemical reaction with oxygen when exposed to atmospheric environment, or the reaction with other oxygen environments. If the passivation protection film is damaged, the stainless steel will continue to be corroded. Unless the passivation protection film is reformed, the corrosion resistance will be restored. Back to the film after the destruction of the situation, most of the time, the stainless steel board will only have a local passivation film is damaged, the corrosion effect, will be formed on the surface of stainless steel plate in small holes or pits, thereby generating a small pit corrosion distribution on the surface of the stainless steel plate. So what is the specific factor that causes pitting on the surface of the stainless steel plate? A large number of data show that pitting may be a chloride ion in the surrounding environment of the stainless steel plate with depolarizing agent. The pitting of blunt metals such as stainless steel is often caused by the partial destruction of some erosive anions to the passivation film. The obtuse state with high corrosion resistance usually requires the oxidation environment, and this environment is also easy to produce pitting. The medium for pitting corrosion is Fe3+, Cu2+, Hg2+ and other heavy metal ions in Cl-, Br-, I- and ClO4- solutions or chloride solutions containing Na+, Ca2+ base and alkaline earth metal ions including H2O2 and O2. The pitting rate increases with the increase of temperature. For example, when the concentration is 4%-10% NaCl solution, the weight loss of stainless steel will be maximized when the temperature reaches 90 degrees, and if the solution is thinner, the maximum value is generally at a higher temperature range. Look at that much, and how do you avoid pitting? The first is to prevent excessive concentration of halogen ions, followed by ensuring the uniformity of oxygen or oxidizing solution, stirring the solution and avoiding small areas where there is no liquid flow, and also enhancing the concentration of oxygen or removing oxygen elements. Of course, it can also improve the pH value. Compared to neutral or acidic chlorides, obviously alkaline chloride solutions lead to less pitting, or totally no (hydrogen and oxygen ions as an anticorrosion agent). In addition, the stainless steel plate is best done at the lowest possible temperature. It can also add passivating agents into corrosive medium. Low concentration nitrate or chromate is effective in many media. It is even possible to use cathodic anticorrosion, and the data show that stainless steel with low carbon steel, aluminum or zinc in the cathode can not cause pitting in the sea water. At the end of the material, austenitic stainless steel with molybdenum 2%-4% can be selected. The material has excellent pitting resistance. It can obviously reduce pitting or common corrosion. Source: China Stainless Steel Plate Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

304 stainless steel pipe from the specifications and appearance properties are very characteristic, the first such wall stainless steel pipe is thicker, the cost and practicality is also higher, but the wall is thin, the processing costs will be substantially increased, in addition to the performance limitation of stainless steel pipe depends on the process, usually seamless steel precision is low, and the pipe wall thickness is not uniform, inside and outside the pipe surface brightness is low and the cost of fixed length is more expensive, pipe inside and outside surface is prone to pitting, black spots and not easily removed, the other 304 detection stainless steel thick wall pipe and the whole type must be carried out off-line processing. Therefore, the stainless steel pipe has shown enough superiority in the field of high pressure and high strength mechanical structure. The stainless steel pipe is pided into hot rolling, hot extrusion and cold drawing (rolling) stainless steel pipe according to the rolling process. According to the difference of metallographic structure of stainless steel, it mainly includes semi ferrite, half martensitic stainless steel pipe, martensitic stainless steel pipe, austenitic stainless steel pipe, austenitic ferrite system stainless steel pipe and so on. According to the specifications, the specifications of stainless steel pipes are mainly based on the GB14975-94 stainless steel seamless steel pipe regulations, of which 304 stainless steel thick wall pipes are usually 1.5-10m in length, and the hot extruded steel pipe is larger than or equal to 1m. The wall thickness of the cold drawn (rolled) stainless steel pipe is 0.5-1.0mm, the length is 1.0-7m, the wall thickness is more than 1.0mm, and the length is 1.5-8m. The diameter of the hot – rolled (hot – Extruded) stainless steel pipe is about 45 types with a diameter of 54-480mm, and a total of about 36 kinds of wall thickness of 4.5-45mm. The diameter of the cold drawn (rolled) stainless steel pipe is 65 of the total of 6-200mm, with a total of 39 kinds of wall thickness of 0.5-21mm. The inside and outside surface of 304 stainless steel thick wall pipe can not appear cracks, folding, cracking, crack, rolling reduction, separation and surface defects, these defects need to completely remove (unless it is specifically used for mechanical processing, and in use) after the removal of the stainless steel pipe wall thickness and diameter of not more than a negative deviation. Some minor surface defects that do not exceed the allowable negative deviations can not be removed. The allowable depth of the stainless steel straight path is also required. Hot rolled and hot extruded steel pipes and stainless steel pipes whose diameter is less than or equal to 140mm is 5% larger than the nominal wall thickness. The maximum depth is less than or equal to 0.5mm, and the cold drawn (rolled) stainless steel pipes are not more than 4% of the nominal wall thickness, and the maximum depth is less than or equal to 0.3mm. The last thing to note is that 304 stainless steel thick wall pipes need to be cut into right angles at both ends before application, and the burrs in the pipe wall are removed. Source: China Stainless Steel Pipe Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

As a kind of steel widely used in Chinese life, stainless steel is highly adaptable and has high corrosion resistance. The main types of stainless steel materials are bars, plates, profiles and wire materials. In this paper, stainless steel bars are used, and stainless steel bars are many, such as round sticks, square bars and hexagonal bars. Stainless steel bars are made from steel ingots, but it is important to note that the atmosphere is so powerful that many materials are corbared by it. Stainless steel bar corrosion resistance is strong, as far as possible but still bear the atmosphere for a long time erosion, a long time, the surface of stainless steel bar will pbaruce a layer of oxide film, stainless steel bar surface itself will turn black, lost the original beautiful luster, despite the existence of the layer of oxide film, easy to play a protective role of stainless steel bar, but this layer of oxide film is just a layer of thin film, if it does not receive special treatment will affect the properties and the application of the stainless steel bars, so before the formal application must by pickling process. Apart from the fact that the surface of the stainless steel bar is exposed too long in the atmosphere, the dust and pollutant particles in the atmosphere will also contact the surface of the stainless steel bar directly, resulting in the contamination of the surface of the bar. To remove the contamination on the surface of the stainless steel, easy to make stainless steel bar processing into acid after a white, so this pickling process is a must, but need to pay attention to what aspects when pickling? Pickling of stainless steel bar is to remove the contaminants on the surface of the bar at the same time, also to remove traces of rust, keep the surface of stainless steel bar original clean, but if do not pay attention to protecting and of the pickling process can destroy the performance of the stainless steel bars, so before pickling stainless steel bars is best to do a first passivation, Mr After passivation can make the stainless steel bar surface into a layer of dense oxide film, and had the layer of oxide film would prevent stainless steel body chemical reaction with the outside world, through such processing can enhance the corrosion resistance of the stainless steel bars. Stainless steel bars are doing cleaning before the corresponding must be ready for work, must be in addition to remove rubbish and contaminants on the surface of the stainless steel bars, in the processing of stainless steel bar surface formation of burr and splash content also clean to remove it, only the surface of stainless steel bar clean dry, then can do formal pickling process. Source: China Stainless Steel Bar Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

Stainless steel pipe fittings are made of bending and deformation. In the process of processing, there will always be some difficult aspects of processing, so it is necessary to focus on how to adjust, cool and lubricate the cutting tools. This article introduces the various forms and difficulties of the mutual processing and deformation of the stainless steel pipes and the corresponding notices. The processing form of stainless steel pipe fittings: 1, the fittings with flanges and round edges. The former refers to the ends of the stainless steel pipes protruding to the inside or the outside side, and the latter refers to the pipes that are raised or grooved in the circumferential direction of the stainless steel tubes. 2. The stainless steel pipe with a stainless steel elbow with variable wall thickness makes the wall thickness change along the length of the tube. 3, the bending pipe of stainless steel elbow, usually more common is, the stainless steel straight tube into different curvature radius bend, such as elbow, bend and so on. 4. The diameter of a stainless steel elbow is changed in diameter, that is, the diameter of a part of the tube or part of the tube is narrowed. 5. A stainless steel pipe with a winding and a seal, which improves the total strength of the stainless steel tube end to the outer or inner side of the tube or the end of the pipe. 6. The section of stainless steel pipe parts is processed, and the circular section is turned into square, elliptical and polygon. The difficulties in the processing of stainless steel pipe fittings: In the process of processing stainless steel pipes, there are more difficult points. One is that the friction between the workpiece and the tool will produce high heat and easy to wear cutting tools. Therefore, the requirements for cutting tool materials are more stringent, and they need to wear resistance and high temperature. And to meet the sharp edge of the edge. The other difficult point is that the machining speed is slow, because the force in the cutting is larger and the production efficiency is not high. In addition, because of the high amount of heat, it is necessary to choose a good cooling oil, usually with sulfur chloride, which will have a good effect. But all of the above are good. The hardest thing is to drill deep holes and tapping. Therefore, when the stainless steel pipe fittings are processed, the workers’ experience and technology should be excellent. Attention to the processing of stainless steel pipe: The first is to pay attention to the processing performance of stainless steel, stainless steel cutting large plastic, high toughness, cutting the consumption of energy, high cutting temperature, stainless steel with low heat conductivity, good heat treatment not easily lead to tool temperature, stainless steel welding bonding coagulation is strong, cutting to form a built-up edge stainless steel hardening tendency is strong, easy to generate cutting surface hardening layer, stainless steel is not easily broken chip cutting blocked, resulting in a stainless steel surface finish is affected. The second is the stainless steel cutting tool, the angle is not easy too, usually is 12 to 30 degrees, the front grinding crescent chip guiding groove can improve the cutting conditions, the posterior horn, is turning to the hard alloy, after the need to take 6 – 10 degree angle, the high-speed steel tool, after the angle should be 8 – 12 degrees, the main angle, the main angle is 60 – 75 degree angle, the need for 8 – 20 degrees, in the rough car should be greater than zero, in the car to less than zero, the nose radius, usually 0.2 – 0.8mm. Third is the need to pay attention to stainless steel cutting when cooling and lubrication, we need to use the cooling and lubricating performance better lubricating oil, so that can effectively improve the work efficiency. Source: China Stainless Steel Pipe Fittings Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

The first generation of duplex stainless steel is 3re60 in the 1960s, which has the problem of welding thermal zone. The second generation was developed in the late 1970s with ultra-low carbon and nitrogen bearing characteristics, the typical number was 2205, and the steel’s pitting equivalent index was 32-39. The third generation is ultra-low carbon, high molybdenum and high nitrogen content, which were developed in the late 1980s. The typical steel is 2507, 32750, etc., and the etching equivalent index is greater than 40. Until now, along with the rapid development of duplex stainless steel production technology, strength and more excellent corrosion resistance of a new generation of duplex stainless steel, super duplex stainless steel has appeared, on behalf of the steel grade is 32707, 33207, 2707, hd. Their performance characteristics are mainly embodied in chemical composition, metallographic structure, corrosion resistance and mechanical properties. First for the chemical composition, design of super duplex stainless steel is a high alloying, in addition to increased again chromium, molybdenum and nitrogen content in stainless steel to enhance its strength and corrosion resistance, also need to regulate other elements of the allocation, which will improve to nearly 50 pitting equivalent index. Followed by the phase ratio regulation, super duplex stainless steel in low temperature solid solution, there is a certain amount of harmful phase in the microstructure of sigma phase, the phase at above 1100 ℃ can basic solution, the ferrite and austenite facies can be roughly half, in addition to avoid the weaker phase first from corrosion, including each of the two phase austenite and ferrite of pitting corrosion resistance of the index design were similar, 32707, for example, the pre values in which each of the two phase of an average difference of less than 1. The third is the corrosion resistance performance, pitting the theory of equivalent to 32707 and 33207 about 50, the critical pitting temperature should be higher than 90 ℃, and 32750 is about 80 ℃. In the standard austenitic stainless steel corrosion fast use environment, super duplex stainless steel can also replace the high alloy austenitic stainless steel and nickel base alloy. In the end, the characteristics of mechanical properties, the yield strength of super duplex stainless steel is twice as high as that of austenitic stainless steel. The yield strength of the heat exchanger for 32707 stainless steel is usually 800mpa, the tensile strength reaches 1000mpa, and the elongation rate of quenching heat treatment state is higher than 25%. And 33207 has better tensile strength. Under the condition of quenching heat treatment, the tensile strength is 20% higher than that of super duplex stainless steel 32750. In addition, the 32707 has the very good impact toughness, its brittle transition temperature less than – 50 ℃. Although the latest “super duplex stainless steel has so many advantages, but at present domestic application or a maximum of 2205 duplex stainless steel such as traditional second generation, super duplex stainless steel output is less, and special research and development of super duplex stainless steel is in early stage. Source: China Stainless Steel Pipe Fittings Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

Usually the heat exchanger can be normal working temperature to 283 ℃, but the temperature is easy to rust stainless steel bolts. The reason is that, in the high temperature environment, the heat cycle can cause some stainless steel tissue to be non – stainless steel. Therefore, when selecting stainless steel fasteners, the requirements must be met to prevent later loss. The following will introduce the optional materials for the stainless steel fasteners. 300 series stainless steel fasteners 300 – line stainless steel is the most commonly used material for the manufacture of fasteners, joints, pipes and pipes. Among them, 304 stainless steel fasteners are the most. 18 – 8 steel is the nominal content of 300 series stainless steel chromium and nickel. The surface of such materials has excellent corrosion resistance, but if the 304 stainless steel is heated to 199 degrees, the carbon content will decrease the content of chromium. This is due to the formation of chromium carbide in the combination of chromium and carbon at high temperature, and the chromium carbide is not antirust. If 304L stainless steel can be used to alleviate this problem, the carbon content of 304L stainless steel is only about 1 / 3 of the 304 stainless steel. The use of 321 stainless steel or 347 stainless steel can avoid the formation of chromium carbide. 321 stainless steel and 347 stainless steel are titanium and niobium respectively, and their chemical properties are very stable. Since titanium and niobium have a larger affinity for carbon than chromium, they are formed at high temperatures with carbon and niobium, respectively, so that chromium can be retained. So 304, 321, and 347 stainless steel are used to make bolts for 300 series stainless steel. In addition, because the strength of 300 series stainless steel can only be strengthened in cold forming, so when the temperature reaches 283 degrees, the thermal cycle will reduce the strength of fastener to the annealing state. If the degree of intensity is not acceptable, even 321 or 347 should be reconsidered, and in this case, the other materials are selected. 400 series stainless steel The chromium content of the 400 series stainless steel is lower than that of the 300 series stainless steel, but there is no carbon deposition problem, and it can be heat treated. It can be used in the working environment with a temperature of 393 degrees. But because the chromium content is only 12%-14%, it will be corroded in a serious chemical atmosphere. However, the chromium content of the 300 system reaches 16%-20%, and it will not corrode. The other 400 series of stainless steel has magnetic properties. The 410, 416, and 430 series of 400 series of stainless steel are used for fasteners. The use of 304 stainless steel is not suitable for 283 degrees in the operating environment, if the decline in strength of materials close to the annealed state can accept, can choose a stable material 321 or 347 stainless steel and the like, and if the strength requirement is high, and the surrounding environment corrosion is not serious, can use 400 series stainless steel can meet the requirements. Source: China Stainless Steel Fasteners Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

Stainless steel pipe can be pided into two kinds of stainless steel seamless pipe and stainless steel welded pipe. According to the shape of the section, it can be pided into stainless steel pipes and stainless steel special-shaped pipes. The largest amount is stainless steel round steel pipes. Besides, the shape of stainless steel special-shaped steel pipes is mostly square, rectangular, semi-circular, hexagonal, equilateral triangles, octagonal, etc. If stainless steel needs to withstand the pressure, you will need to do a hydraulic test to measure the quality and performance of the stainless steel pipe pressure, only at the prescribed pressure without leakage, wet pipe or expansion is qualified, but also need to do some stainless steel pipe crimping, flaring and compressed according to the corresponding standard or the buyer test requirements. The characteristics of stainless steel seamless pipes can be seen from the following aspects. First, chemical analysis of the chemical composition of stainless steel is used to see whether the chemical components conform to the standard requirements. Secondly, the pressure test can be carried out by pressure and water pressure test. The specified pressure value does not keep less than 5 seconds, and does not leak. The conventional supply water pressure test is 2.45MPa. The pressure pressure test was P=0.5MPAa. Corrosion-resistant test is also needed. The corrosion-resistant steel pipe for industrial corrosion is tested according to the standard or the corrosion method of the two sides, and the stainless steel pipe can not appear intergranular corrosion tendency. In the field of process performance testing, flattening, stretching, impact, expansion, hardness, metallography, bending and other experiments are necessary. Seamless steel pipe is made of steel ingot or solid pipe billet through perforation, and then processed by hot rolling, cold rolling or cold shifting. Therefore, the general seamless steel pipe can be pided into two kinds: hot rolling and cold rolling seamless steel pipe. In addition, the specifications are usually represented by the diameter of the outer diameter of the wall. The hot-rolled seamless steel pipes include general steel pipes, low and medium pressure boiler pipes, high pressure boiler pipes, alloy steel pipes, stainless steel pipes, petroleum cracking pipes, geological steel pipes and other kinds of steel pipes. The cold-rolled seamless steel pipes include carbon steel pipes, medium and low pressure boiler pipes, high pressure boiler pipes, alloy steel pipes, stainless steel pipes and oil cracking pipes. There are also carbon thin-walled steel pipes, alloy thin-wall steel pipes, stainless steel thin-walled steel pipes, special-shaped steel pipes, etc. The hot rolled seamless steel pipe is usually greater than the outer diameter 32mm, wall thickness in 2.5-75mm, cold-rolled seamless steel pipe diameter can be as small as 6mm, the wall thickness can be thin to 0.25mm, thin-walled stainless steel pipe diameter can reach 5mm, the wall thickness is less than 0.25mm, cold-rolled stainless steel pipe precision is higher than that of hot rolling size. With the development of social economy, stainless steel pipe is widely used. Source: China Stainless Steel Seamless Pipe Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

At present, continuous casting is mostly used in the production of stainless steel, and the caster is mainly vertical and arc. Compared to the traditional ingot – rolled billet, the quality of the stainless steel continuous casting billet is better, the yield of the metal is increased by 10%-15%, and the effect is obviously reduced. At present, the main technology of manufacturing stainless steel seamless pipe is hot extrusion. While gradually eliminating hot rolled steel pipe sets, extrusion unit is becoming the main unit of stainless steel seamless pipe production all over the world. In addition to a small amount of extrusion for extrusion, most of these extruding units are used to make steel pipes, the main varieties are stainless steel seamless pipes. Compared with the rolling process, the extrusion process is characterized by the compression stress of three directions in the process of metal deformation. Under such optimum stress state, stainless steel seamless pipes with high type and high deformation resistance can form satisfactory deformation, internal and external surface quality and microstructure state. Through the extrusion process to the maximum benefits of stainless steel seamless pipe can be as raw materials directly to continuous casting, stable quality of stainless steel seamless pipe, and the replacement is flexible, can directly produce hot extrusion finished stainless steel seamless pipe, can also be used to produce various kinds of special-shaped stainless steel seamless pipe. However, the drawback of the manufacture of stainless steel seamless pipe by extrusion method is that the rate of production is low. In order to increase the yield of stainless steel seamless pipe, the production process is optimized. If the high required variety usually uses the pre drilling, the hydraulic piercer expansion and the extrusion process. The requirement of cold processing of raw materials in general pipe according to the actual situation with different production processes, such as small size stainless steel seamless pipe with solid billet directly in the vertical hydraulic punch and extruded pipe; medium size stainless steel seamless pipe with blank is pre drilled holes, vertical hydraulic reaming and extrusion punch into large steel pipe; the specifications with blank pre drilling larger holes, directly into the extrusion pipe. Obviously, it is a cost-effective method to produce finished products and provide raw materials for cold processing by extrusion. In addition, the cold rolled stainless steel seamless pipe mostly uses cold rolling and cold drawing as the auxiliary production process. The stainless steel seamless pipe of 50%-80% should be made into finished products by cold processing. Therefore, the cold processing equipment will develop greatly. There are three main cold processing technologies, which are cold drawing, cold rolling, cold rolling and cold drawing. The cold rolling and cold drawing process of the stainless steel seamless pipe in foreign countries is mostly cold rolling and cold drawing, which is the main part of cold rolling. At present, the cold rolling mill can complete the large wall reduction and the large reduction of the stainless steel seamless pipe, and 80% of the deformation can be done directly on the cold pipe mill. The production requirements of different specifications and varieties can be achieved by changing the wall of cold rolling, changing the specification of steel pipe and controlling the outer diameter with cold drawing. This is the advantage of the quality of the finished production process of stainless steel seamless pipe, and the pipe wall thickness and fine and high surface quality, high precision cold drawn steel pipe diameter, cold processing cycle short, omitting the middle of degreasing, heat treatment, necking, straightening process and pipe material consumption, effective energy saving, but also simplify all kinds of raw materials, so as to expand the scale of production. Source: China Stainless Steel Seamless Pipes Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)