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Chromium martensitic stainless steel and ferritic stainless steel according to different conditions can cause stress corrosion cracking (mainly intergranular cracking) or hydrogen embrittlement, but this kind of stainless steel in MgCI2 or NaCI solution, resisting performance is far stronger than austenitic stainless steel, and under the condition of load stress is not strong, will not cause cracking. The austenitic stainless steel is liable to crack in high temperature environment containing chloride aqueous solution. In the cooling water, the water vapor in the CI – probably in more than 50 PPM, temperature in the case of more than 50 ℃ about likely to happen, there are in many cases, the dissolved oxygen in a few parts per million of C1 – concentration will also form the corrosion cracking. It is more likely to cause corrosion cracking near the boiling point or boiling point of the solution, and sometimes in a very short time. 304 stainless steel has cracking sensitivity in high temperature and high pressure water. The austenitic stainless steel in MgCI2 solution will be affected by stress corrosion cracking. 1 nacl concentration and dissolved oxygen on the influence of the stress corrosion cracking of stainless steel 304 (temperature at 260 ℃, load stress is 21000 psi) is one of the important influencing factors as related to stress corrosion cracking, in addition to stress) chloride concentration, temperature, degree of processing also leads to great impact. Temperature rise can cause stress corrosion cracking in stainless steel, and the influence size of stainless steel is also changed according to the type of alloy and the residues stress. In terms of degree of stainless steel processing, usually in the range of is not how big along with the deepening degree of stainless and much easier to crack, but it is important to note when processing degree of more than 10%, stainless steel materials will be difficult to crack. Pitting corrosion is in the case of stainless steel passivation membrane stability, when the solution PH value near the neutral, antioxidants and halogen ions, C1 – in particular, passivation membrane will be destroyed by part forming cell anode, because of the passivation membrane as cathode, making this area form a larger potential difference, and in a short period of time the phenomenon of erosion depth stainless steel. In order to avoid corrosion of stainless steel, there are mainly electrical and anti-corrosion, adding preservatives, surface spraying, controlling PH value, removing oxidant, etc. The surface treatment of stainless steel is also best to do some work on the residual stress of the surface, so that the stress can be compressed. Source: China Stainless Steel Pipe Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

Because of its excellent mechanical properties, high hardness and wear resistance, stainless steel has been widely used in the military parts processing field. Their surface treatment is carried out after heat treatment, solid solution and aging, because the heat treatment process of those thicker oxide skin and material itself has some particularity, resulting in pickling passivation processing is very difficult. Pickling passivation process The process of stainless steel surface treatment is not complicated. However, in the actual processing, the pickling passivation process is very difficult, mainly for two points. It is a stainless steel material can not rust according to conventional methods to remove oxidation surface skin, followed by stainless steel after the passivation processing technology will not meet air corrosion, will not damage the workpiece dimensions and surface finish, is actually in the process must form a passivation film surface passivation with strong oxidizing acid wash this agent to the parts, so as to obtain the corrosion resistance. The main elements in stainless steel with titanium, chromium, nickel, silicon, manganese and molybdenum oxide, their skin is relatively thick and dense in the heat treatment process, and compact oxide film consisting of iron, chromium, nickel and oxygen with spinel structure (FeCrO4), its chemical properties are very stable. This oxide film is not easy to remove. Parts for low temperature solidification and aging Low temperature solid aging stainless steel parts are thin, usually light purple, and it is easier to handle the oxide skin of such stainless steel parts. After pickling, the surface oxide can be basically clean, and it will not corrode itself. The stainless steel parts are not covered with ash and can be directly passivated. For high temperature solid fusion aging parts High temperature solid aged stainless steel parts have relatively thick oxide scales and are usually black purple or even black. Because the surface of stainless steel parts will produce thick, dense and complex oxide skin, it is difficult to remove the oxide scale of stainless steel parts by pickling. Removal of such oxide should be carried out according to the process of loosening oxide scale, pickling and removing dust. Because of the stainless steel plate after the loose oxide process, the surface of stainless steel parts will generally attach a layer of ash, need to remove this layer of ash and then passivation treatment. Removal of the operation process of hanging ash is more important, mainly passivation process, after pickling parts in the air corrosion resistance is poor, if exposed to the air, stainless steel parts will rust surface. In order to enhance its corrosion resistance, it is necessary to produce a compact and corrosion resistant passivation film on its surface, so as to achieve the purpose of corrosion resistance. Source: China Pipe Fitting Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

The advantage of duplex stainless steel is its excellent corrosion resistance, especially local corrosion resistance. In addition, its strength is equivalent to two times of austenitic stainless steel, toughness is also very good, not only for the traditional paper-making and chemical processing industry equipment, but also used in important public engineering fields, such as bridges and highway construction. This paper introduces the development trend of duplex stainless steel from two aspects of materials and applications. Economical duplex stainless steel There are three kinds of mature duplex stainless steel developed abroad. One of them is UNSS32001. It is a new type of steel which is difficult to produce delta phase. It has been used in deep sea pipeline cable and automobile frame. The second grade is UNSS32101, which can be used in medium corrosive environment, such as the white tank of paper mills, etc., and its potential use is very wide. In recent years, the steel has been paid special attention to the basic structure, and has been successfully used in the construction of bridges. These two grades of steel are manganese and nitrogen instead of nickel, reducing nickel and chromium content, their corrosion resistance and 304LH equivalent, because it does not contain molybdenum, it is cheap, but not suitable for coastal structures. The third grade is UNSS32003, whose internal nickel content is 3.5%, higher than the first two kinds of stainless steel, and also contains 1.7% molybdenum, can be used in the depth of 1200m submarine transport of sulfur free or slightly sour gas pipeline system. Super duplex stainless steel and duplex stainless steel SAF2507 steel developed in Sweden is the use of the most widely used steel super duplex stainless steel, has been incorporated into the multi criteria, the microstructure of the balance between the good, is more likely to be in the hands of similar stainless steel in the production process, especially has very excellent in high chloride environment localized corrosion resistance, making the heat exchanger of sea oil pipeline cable, seawater desalination, flue gas desulfurization device used frequently. The Zeron100 steel containing W and Cu has been developed in the UK. The steel has been successfully used in seawater jet pumps and lift pumps because of its good wear and corrosion resistance. From a technical point of view, the sea is the most valuable use of the industrial field of super duplex stainless steel, but is in order to adapt to the current wellhead improvement of oil and gas recovery method control system for higher corrosion resistance requirements and deep seabed temporary piping and piping cable demand, existing duplex stainless steel in strength and corrosion resistance has been insufficient, the Swedish Sandvik company designed a new series of super duplex stainless steel SAF2906, SAF2707HD, SAF3207HD etc. with strength up to 1000MPa ultra high strength and excellent corrosion resistance of steel. In addition, the Alloys developed by Langley controls the corrosion resistance and pitting corrosion resistance of the Ferralium 225-SD50 steel, which is higher than that of other super duplex stainless steel. Popularization and expansion of application The application of duplex stainless steel is more and more extensive. Traditionally, its excellent local corrosion resistance, especially the stress corrosion resistance, is considered as a corrosion resistant functional material. Now, from its strength, the application of duplex stainless steel as a modern structural material should be paid attention to. Deepwater oilfield Because of the increased demand for oil and gas, driving deeper and deeper undersea oilfields, this has rapidly increased the use of deepwater wells. The main oil production platform implements the operation of standardized pipe bundles to provide water, power, decompression and communication over wells. In addition, in order to ensure the mobility of oil, chemical injection is required in many deep sea intake pipes. In order to increase production, the oil well is acidified by pipeline cable. The pipeline cable has become the lifeline of the seabed mining system. Faced with deep-sea exposure environment, it means that high mechanical properties, internal and external corrosion resistance, stress corrosion cracking and other requirements for pipeline cable are required. The preferred material of deepwater pipeline cable should be super and super duplex stainless steel, but because of the price and manufacturing problems, the galvanized 19D duplex stainless steel (ZCLDSS) has been developed. The design life of the pipeline cable is 20 years, and it has been popularized and applied at present. In addition, the economical low nickel AL 2003 steel has also been used in the East Malaysia oil field in 2006, the depth of more than 1200m submarine pipeline. Adding copper Ferralium225-SD50 duplex stainless steel has become a container material 7000m deep seabed placing equipment and cables, and the pressure on the shell were used as underwater locator and extremely accurate controllable deep-sea acoustic release transponder and bearing components (7000m deep sea is equivalent to 700 ATM, HI2.5 tons of payload). The newly developed SAF 2906 and SAF3207 super super duplex stainless steel of Sweden Sandvik has super high strength and corrosion resistance, and the highest working temperature is 60 and 90, respectively. Chemical tanker One of the typical examples of the strength of duplex stainless steel is the wavy wall cargo tanks of chemical tankers. In 2002, the Hubei Qingshan shipyard used the UNSS3I803 (2205) wave panel made by Arcelor company to build the first 18500 DWT cargo tank for Belgian shipowners, and built many other vessels successively. In 2007, TISCO made the first domestic 2205 duplex stainless steel to provide the East Asia Shipyard with a cargo tank of 9000 tons (2205 tons, 600 tons), 5500 tons and 3750 tons. It has been used for 16 ships and is still in contract. 22-09 welding rod is also provided by domestic, but the welding wire still needs import. This is a great breakthrough, China classification society also has 2205 (S32205), 2507 (S32750) and copper (S32550) 2506 kinds of people into the standardized production. Building structure The first is the application of bridge and concrete reinforcement, there are more than ten bridges in the world using duplex stainless steel, mostly walking bridge. Such as the first British York bridge and Sweden’s Aparte bridge are used 2205 steel, in recent years, the new bridge in Norway and Italy Rffolo bridge, has used the economical 2101 steel. Later, duplex stainless steels were also used in highway bridges, especially those that were sensitive to chloride induced corrosion. The Brooklyn bridge in New York uses 2205 steel bars. The high strength and high elongation of the steel give it excellent fatigue resistance, and the service life is 2 times higher than that of the ordinary steel bars. The stonecutters bridge in Hongkong, China, uses 2000 tons of 2205 steel plates to make the outer surface of the upper part of the pylon. The service life is estimated to be 120 years without repair. Hongkong to Shenzhen cross Bay 3.2 km long highway channel bridge, about 1250 tons, 2205 and 316 used as high-speed road steel. In addition, Wuhan Tianxingzhou bridge for the public, railway cable-stayed bridge, 2205 10-20mm board produced 20 tons of TISCO, cutting, welding angle, as cohesive pier and cable-stayed steel components. The second is the use of construction facilities, and Barcelona, Spain, uses 500 tons of 4mm thick 2101 to build flour storage. The United States will matt surface processing of AL 2003 1500 tons of sheet for building the world’s largest stainless steel roof (the roof of Doha International Airport, India, Qatar) by Outokumpu company provided 200 tons of electrolytic polishing surface of 2101 duplex stainless steel plate, made with 25mm, with 38mm, with 50mm three specifications 20 kilometer long pipe will be used. An Mumbai street overpass. Source: China Pipe Fittings Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

The chemical elements are often used in the steel industry, there are about more than 20 species, is stainless steel, commonly used elements of a dozen, in addition to iron, can affect the microstructure and properties of stainless steel elements are carbon, chromium, nickel, manganese, silicon, molybdenum, titanium, niobium, titanium, manganese, cobalt, copper, nitrogen etc.. When several elements coexist on the same stainless steel matrix, their effects are more complex than when they are alone, so we should not only consider the elements of its function, but also pay attention to their mutual influence, so the microstructure and properties of stainless steel is the sum by the effects of various elements. Chromium plays a decisive role in stainless steel There is only one element that determines the stainless steel property, that is chromium, and each stainless steel must have chromium. The fundamental reason is that the addition of chromium to the steel can promote the movement of the internal contradictions in the steel to help resist corrosion damage. That is, chromium increases the electrode potential of Fe based solid solutions, and chromium absorbs iron electrons to make iron passivated. Passivation is the phenomenon that the corrosion resistance of metals and alloys is improved because the anodic reaction is prevented. There are many theories about passivation of metals and alloys, including thin film theory, adsorption theory and electronic arrangement theory. The duality of carbon in stainless steel Carbon is one of the main elements of industrial steel. Its performance and microstructure are largely determined by the content and distribution of carbon in steel, and the effect of carbon is very obvious in stainless steel. Effect of carbon on microstructure in stainless steel is mainly manifested in two aspects, one is the stable austenite carbon element, and its effect is very strong (about 30 times of nickel), on the other hand, because of carbon and chromium and chromium have great affinity, forming a series of complex carbide. Therefore, according to the strength and corrosion resistance of parts, carbon in stainless steel is contradictory. So from the use of different requirements, choose different carbon content of stainless steel. The role of nickel in stainless steel Nickel is the excellent corrosion resistance of elements, is an important alloying element of alloy steel. Nickel is the main element in the formation of austenite stainless steel, but low carbon nickel steel to obtain pure austenite and nickel content to achieve 24%; and only 27% of nickel to stainless steel in some medium corrosion resistance improved significantly. So nickel can not be made into stainless steel alone. However, nickel and chromium exist in stainless steel at the same time, nickel containing stainless steel has a lot of valuable properties. So that, effect of nickel in stainless steel, high chromium steel is the organization change, so that the stainless steel corrosion resistance was improved to a certain extent. Manganese and nitrogen can replace nickel in chromium nickel stainless steel Cr Ni austenitic steel has the advantages of many, but now because of the nickel base heat-resisting alloy and nickel containing less than 20% of the heat resistant steel of the application and development of chemical industry, and the growing need of more and more large amount of stainless steel, but less nickel deposits and concentrated in a few areas, so produced a contradiction the nickel in the supply and demand in the world. Therefore, in the field of stainless steel and many other alloys (such as forging steel, tool steel, heat resistant steel etc.), especially the lack of nickel resources in the country, a large number of development and generation of nickel nickel with other elements of scientific research and production practice, research and application is more to manganese and nitrogen instead of stainless steel and heat resistant steel of nickel in this area. The effect of manganese on austenite is almost the same as that of nickel. But rather, the role of manganese is not generated is austenite, which can reduce the critical quenching speed of stainless steel, increase the stability of austenite during cooling, inhibit decomposition of austenite, the high temperature formed austenite to maintain the normal temperature. To improve the corrosion resistance of stainless steel, little effect of manganese. Source: China Stainless Steel Pipe Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

Stainless steel welded pipe production will not cause too much pollution. According to the actual statistics, more than 1 tons of mud each production of stainless steel welded pipe produced only 0.2kg, and the main component is more than sediment and there is no air or water chemical reaction, in addition to stainless steel tube production process does not produce poisonous gas, tap water, cooling water is ordinary, recycling rate is very high. If the tube used in the production of decoration and structure even without annealing, polishing is only half finished, and the production of fluid conveying pipes, are now using the online annealing technology, without pickling, but also to prevent the effects of waste on the environment in the process of pickling acid. Japan, Italy and other developed countries also retained stainless steel welded pipe industry, indicating that the development of this industry is optimistic. Stainless steel welded pipe is a kind of energy saving and environmental protection products, with stainless steel water pipe, its advantages are mainly manifested in several aspects. First of all, stainless steel welded pipe at low temperature is not brittle, high temperature insulation performance is good, so the hot water transportation will not cause energy waste. The second is thestainless steel pipe internal surface is smooth, low friction and clean, thus reducing energy waste water, after all, energy saving is significant, such as Japan, Singapore and other countries because of less fresh water, the basic use of stainless steel welded pipe as conveying pipe, the leakage rate decreased about 8% carbon steel pipe, and the basic can be used for more than 70 years, without fear of damage due to corrosion of pipeline. In addition, the stainless steel welded pipe can guarantee 100% recovery. Waste stainless steel welded pipe can be recycled 100%, will not cause pollution, which conforms to the current national energy conservation and environmental protection requirements of Scientific Outlook on Development. Application prospect of stainless steel welded pipe Stainless steel pipe can only be finished 1.5, the range of downstream development it is very wide, a lot of carbon steel can be used where they can use stainless steel pipe, and more excellent performance. Stainless steel pipe tube for food hygiene, not only beautiful enough health, but also easy to clean, and there is no better than the stainless steel pipe material for the production of food hygiene tube. The production of stainless steel welded pipe anti-theft door, burglarproof window, stair handrail has also been widely used, a lot of wood products over the past can be used to replace the stainless steel welded pipe. The automotive industry is also a very large field of stainless steel welded pipe, heat exchanger used in power plants also need to use a large number of stainless steel welded pipe. Usually, a generating unit needs about 50~60 tons of stainless steel welded pipe, and other heat exchangers, such as sugar mills, chemical plants and other industries, also use a large number of stainless steel welded pipe. From the sky to the ground to the ocean, stainless steel pipe can be applied in the field everywhere, with the understanding of the future of stainless steel welded pipe deepened, its status will be more important. Source: China Stainless Steel Welded Pipe Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

In order to solve the processing hardening caused by cold processing of stainless steel pipe, it is necessary to reheat treatment in the process of forming. Therefore, whether to carry out the fire treatment has a very direct impact on the processing technology and the cost. We all know that when the stainless steel material is near or less than room temperature deformation, it will harden and increase the strength and hardness of the stainless steel material. In essence, not all stainless steel pipes can be expected to be processed. For example ferritic 400 series stainless steel pipe, in the cold processing of it, will only produce a small amount of deformation, otherwise it will produce sudden destruction or even cracking. For example, 430 and 446 stainless steel pipes themselves have notch sensitivity, so their supply status needs to be marked as annealing. When it is necessary to process the process, it is necessary to conduct the tempering process. Hardened martensite stainless steel is also supplied in annealing status, otherwise such stainless steel is usually reinforced or reinforced with quenching. However, austenitic stainless steel pipes can be supplied in a larger range of cold-processing hardness. The following is a list of mechanical properties related to the austenitic stainless steel pipes. Not all sizes and steel austenitic stainless steel pipes can be processed after tempering. Stainless steel, such as 201, 202, 301, 302 and 304, is very suitable for cold drawing. Stainless steel, with high content of alloy elements and low hardening rate of cold processing, is not widely used to produce tempering products that are more than 1/2 cold. 305, 316, 317 and 310 stainless steel belong to the latter category. With the increase of nickel content, the trend of hardening of stainless steel materials will decrease. It is important to note that some non-standard chrome-manganese austenitic stainless steel pipes also greatly increase the processing range of cold drawn steel pipes. It can be seen that the rule of small size stainless steel pipe may change when machining production. When production is higher than annealing hardness of small size stainless steel pipes, especially if you want to have 1/2 cold and hard energy, you need to consider the use of equipment that specializes in small stainless steel pipe. Because of the utilization of raw materials, the rate of success is a must, and the above basic knowledge is beneficial to improve the yield of stainless steel pipes. In the process of cold-drawing stainless steel pipe, it must consider the limitation of machining dimension to the production of stainless steel pipe. Because of price limitation, lubricant performance and the intrinsic factor of the above analysis, only certain sizes of stainless steel pipes can be cold-drawn and processed under various tempering conditions. Source: China Stainless Steel Pipe Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

In the product application of stainless steel bars, sometimes affected by medium corrosion or external force, will form some cracks in the rod. This paper mainly talks about the causes of cracks in the stainless steel bar. Bubbles in stainless steel bars Cracks in 304 stainless steel bars are caused by bubbles on the surface of the skin or cracks on the surface. If the crack is perpendicular to the surface of the stainless steel and the length is about 0.8-1.5mm, there is no decarburization on both sides, which is caused by the bubbles under the skin. This is because there is a large amount of gas in the molten steel. When the molten steel is solidified, the gas is not discharged to form bubbles. The outer layer of the slab near the bubble is called subcutaneous bubbles, honeycomb shaped perpendicular to the surface of the billet, billet after rolling, it can weld most inside the bubble. But if the subcutaneous bubbles near the slab surface is too close, when heated due to slab surface oxidation or burning of the bubble surface will be exposed to the air bubbles in the oxidation, unable to weld, so that the stainless steel surface cracks. Stainless steel is impure Stainless steel six corner rod crack is caused by inclusions in stainless steel cracks, cracks and stainless steel surface forming a certain angle, length is about 1.0-2.5mm, slightly decarburization on both sides, decarburization layer 0.10-0.15mm. There are inclusions on both sides of the crack and the tail, and the ferrite bands are formed. Stainless steel rod folding Stainless steel square steel crack formation because of surface folding caused by the crack and the steel surface 15 -75 angle, the length of about 1.5-3.5mm, tail showing whirlpool, on both sides of slight decarburization, decarburized layer of 0.15 ~ 0.25mm, the crack in iron oxide existed. It is in the form of stainless steel rod surface along the direction of rolling straight or zigzag, continuous or discontinuous in partial or full length of steel. So it is known that this is the folding formed during the rolling of stainless steel. The main reasons of the formation of folding is finished before the stainless steel rod rolling with a handleonapot; second is in the process of rolling each pass from the handle, flash, serious scratch, damage, and roll ring groove wear etc., will lead to product surface collapse; in addition a serious defect such as blank. If improper cleaning may also lead to finished folding. So the main measures to reduce or prevent folding appear through the rational design of pass, the accurate estimation of the spread, precisely adjust the position of roller groove, reduce or eliminate the finished product before rolling the handle, flash, scratches and other defects; the second is to carefully clean the blank surface defects. According to the causes of crack formation of stainless steel rod, can reduce or prevent crack using the following measures, one is to use the method of deoxidation alloying process is reasonable, appropriate control of oxygen content in molten steel, as far as possible to reduce the content of inclusions in molten steel; secondly, in the pouring process of pouring mining with full protection, to prevent the molten steel two oxidation, increase the purity of the billet, billet and reduce subcutaneous bubbles; the third is overheating degree of reasonable control of continuous casting steel, with excellent physical and chemical properties of slag, weak cold and ensure uniform cooling by two cooling, avoid the slab surface crack; the last method is through the rational design of pass, accurate estimation spread, precisely adjust the position of the roller grooves, carefully clean the blank surface to reduce or eliminate the serious defects before finished rolling handle, flash, scratches and other defects. Source: China Stainless Steel Bars Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

Stainless steel plate is a kind of composite plate with excellent corrosion resistance and corrosion resistance. Before welding, it needs a lot of preparation process, such as materials, tools, processing technology and so on. First of all, the stainless steel plate should be cleaned up before and after welding, and the surface of stainless steel plate should not be dirty or iron filings. If the surface of stainless steel plate is not clean, it needs to be cleaned in time. Secondly, when welding, it is also necessary to select suitable materials, for example, to select the deposited metal with the content of alloy element not less than the selected composite layer. In the choice of electrode, the same should choose the appropriate model, as long as this can be in the welding time, the stainless steel clad material dilution to supplement. In addition, before welding, the first to be cutting, stainless steel plates in the cutting of the need to ensure that the groove of the board processing, the use of mechanical processing, so that the cutting groove after the cutting surface is usually more smooth. In addition, can also use the shears cutting or plasma cutting way, but to pay attention to is, in cutting, double layer stainless steel plate is up to, and also to prevent slag drop in the complex layer. The groove must be checked before cutting the stainless steel plate. The groove must conform to the size and specification of the drawing. When selecting the groove, the groove should be selected for easy operation, which can reduce the filling technology after welding. In the groove processing, but also choose the mechanical way, if use other ways, first of all to remove the stainless steel plate on the oxide layer. After the completion of the groove processing, but also to the surface inspection, excellent cutting surface, stainless steel plate on the groove is not layered or cracks, otherwise it is unqualified products, need to be re processed or repaired. In the selection of stainless steel plate welding parts also have certain requirements, especially in the thickness must be controlled well, to the thickness of the layer as the standard to choose. Usually, the same material with the same metal color as the surface of the stainless steel plate is usually selected. The most important is the stainless steel plate in welding, the side of the annex welding should be carried out according to the requirements of the drawings reasonable, need to ensure accuracy. Source: China Stainless Steel Plates Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

The production process of stainless steel bar is more, the product is bundled neatly, and the surface of stainless steel rod is also very beautiful. In the production, the manufacturer is how to deal with the surface of stainless steel bar? This article to understand it. Attention should be paid to all aspects of the production of stainless steel bars, grinding and surface processing of stainless steel bars need to be careful and meticulous. With the use of stainless steel bars more and more widely, more manufacturers will have larger orders, we must not be careless, we must deal with stainless steel rod surface. The surface treatment of stainless steel bars is the first process of polishing, which is part of the polishing process. In fact, there are many techniques for the surface treatment of such stainless steel bars. If there is a defect on the surface of the stainless steel bar, it must be polished in manual way at this time, and then the processing decision of the bar is made. Now stainless steel bars have been applied to many fields, and their chemical properties are different from those of other stainless steels. For stainless steel bar surface treatment, first to detect the workpiece in all directions, if the quality is not qualified, such as butt joint is uneven, the solder joint uneven depth, it is best to rework processing, until the stainless steel rod workpiece to determine the defect after grinding. In the process of grinding stainless steel rod, we need to carefully remove the solder joints and scratches left by welding, so that the surface treatment is clean. There are two kinds of grinding: rough grinding and fine grinding. After grinding, the surface of the stainless steel rod will be very bright, and the trace of the seam can be completely eliminated. After grinding, the stainless steel bar work piece shows the effect of approaching the mirror surface. Polishing is also a process for treating the surface of stainless steel bars. There are generally three methods, namely mechanical polishing, chemical polishing and electrochemical polishing. Mechanical polishing is especially suitable for polishing large pieces, small pieces are difficult to achieve very good results, and are suitable for batch production. The advantage of this method is that it can be very good surface treatment, but the drawback is that the cost of investment is higher, the intensity of labor is relatively large, in addition to serious pollution problems, so many manufacturers are not optimistic. Chemical polishing is the same, the cost is low, without the use of large machinery and equipment, flexible investment, polishing speed is also very fast, but the drawback is that the brightness of polishing is not good enough. The electrochemical polishing process is more stable, easy to operate, and lower investment costs, pollution is small, as long as a one-time investment after the cost is no longer necessary, and now most enterprises use this. Source: China Stainless Steel Bars Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

Over the years, with the rapid development of various fields, the application of various stainless steel pipe fittings is more and more, of which stainless steel elbow is also true. So what should be noticed in the installation of stainless steel elbow? If the stainless steel elbow has been placed for a long time, then in the installation before the regular inspection, long-term exposure outside the surface must be cleaned regularly, remove dirt, neatly stored in the indoor ventilation place, prohibit stacking or open-air storage. Always keep the stainless steel elbow ventilation, keep it clean and neat, according to the correct storage method. Before the installation of stainless steel elbow, stainless steel elbow to various standards carefully checked for compliance with the requirements, such as the path is not in line with demand, and defects may be formed in the process of transporting the removal and removal of dirt, stainless steel elbow, do the preparation before installation, need to prepare work arrangements. When the stainless steel elbow is installed, the stainless steel elbow can be directly installed on the pipeline according to the connection method and installed according to the requirements of use. Under normal circumstances, the stainless steel elbow can be installed in the appropriate place on the pipeline, but the need to pay attention to the convenience of operation, pay attention to the stainless steel elbow, medium flow should be from the bottom of the valve to the upstream, then the stainless steel elbow can only be installed horizontally. Stainless steel elbow should pay attention to sealing performance in installation, avoid leakage appearance, thus affecting the normal operation of the pipeline. Stainless steel elbow valve packing gland bolts must be evenly tightened, not crooked, avoid bumps, prevent stem movement or cause media leaks. Stainless steel ball valve, stainless steel globe valve, stainless steel gate valve is used, the best choice of full open or full closed, do not do scheduling flow, to avoid sealing surface erosion, thereby accelerating wear. There is a reverse sealing device in the gate valve and the upper thread stop valve. When the handwheel is screwed up to the top position, the medium in the pipe can be leaked out from the filler. Source: China Stainless Steel Elbow Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

Generally speaking, the most difficult way to test whether a material is stainless steel is to see whether a magnet can adsorb or not, and that it is stainless steel, which is not familiar with the performance of stainless steel. In fact, this method is very one-sided and unscientific. Austenitic stainless steel is austenitic stainless steel at room temperature. Chromium is about 18%, nickel is about 8%-10%, and carbon is about 0.1%, so it has a relatively stable austenite structure. Chromium manganese austenitic stainless steel is developed on the basis of chromium nickel austenitic stainless steel, adding manganese or nitrogen to stainless steel to replace the precious metal nickel element. The austenite element in the tissue has nitrogen besides manganese, and also has a suitable amount of nickel. Manganese plays an important role in stabilizing austenite in stainless steel. Generally speaking, austenitic stainless steel is not magnetic or weak magnetic, but some austenitic stainless steel is not necessarily a complete austenitic structure, so some austenitic stainless steel will show weak magnetic. Martensitic stainless steel and ferritic stainless steel are magnetic, which is due to the ferromagnetism of martensite and ferrite structure. Therefore, only when the permeability of the austenite stainless steel is close to 1 in the vacuum, the austenite stainless steel is close to nonmagnetic R. The reason for the formation of magnetism of stainless steel is that the segregation of stainless steel billet or improper heat treatment will lead to the formation of a small amount of martensite or ferrite in austenite stainless steel, which will have weaker magnetic properties. After cold processing, the microstructure of stainless steel will be partly transformed into martensite, and the greater the degree of cold working deformation, the more martensite transformation, the higher the corresponding magnetic. When the stainless steel workpiece is machined, its edge is closely contacted with the high hardness carbon steel, so that it is made up of carbon steel at the edge of the working face to produce magnetism. So how to eliminate the magnetic properties of stainless steel? First of all, to eliminate the magnetism of stainless steel completely, the stable austenite structure can be recovered by high temperature solution treatment so as to remove the magnetism. The concrete method is to heat up the stainless steel material to about 1050 degrees, and then use cold water to quench the carbide in the stainless steel. The second is applying an alternating magnetic field decay, it can be used on DC demagnetization machine, a welding gun welding clamp at one end of the stainless steel material, the other end and then the other welding tongs clamped material diagonal, current decreases, and can be pided into several times; but the time can not be too long, and the number is not too otherwise, easy to burn machine. Source: China Stainless Steel Pipe Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

Generally speaking, there are three kinds of polishing processing technology for stainless steel pipe elbow, which are mechanical polishing, chemical polishing and electropolishing. Among them, there are three terms in mechanical polishing, need to understand, first of all, abrasive said stainless steel pipe elbow polish wax, eliminate the excess particles, so that the surface is very neat. The oil is said to be polished wax to make the elbow lubrication and cooling function, so that the surface of the tube has stearic acid, fatty acids and paraffin and other effective substances. The cutting force is the force required for the whole process of smoothing the polished stainless steel elbow. When the stainless steel pipe elbow is placed for a long time, it is necessary to check and maintain it regularly. For stainless steel pipe elbows exposed outside of the parts, often need to ensure clean, remove dirt, keep clean, in addition, stainless steel pipe elbow should be placed in the indoor ventilation and dry place, can not completely stacked and exposed outdoors. Stainless steel pipe elbow itself ball valve, wafer check valve, gate valve use time, can only be fully open and fully closed, the middle can not adjust the flow over time can prevent the sealing surface from corrosion and wear damage, usually the valve and the valve on the screw contained within the inverted sealing for manual hand wheel rotation to the the upper head surface can achieve long-term rust free, no corrosion. In addition, the installation of adjustable stainless steel pipe elbow, it is necessary to maintain its sealing condition, otherwise it will lead to its inability to work properly. There are two main types of forming process of stainless steel pipe, one of which is hot forming, hot forming process is the use of stainless steel pipe elbow bend drawing machine, mould and heating device, the set of billet in the mold on the forward movement in the push for the machine, and in the movement to be heated and expanded diameter and bending. The deformation characteristics of the hot pushing elbow is based on stainless steel pipe elbow plastic law of constant volume deformation before and after determining the tube diameter, tube diameter less than the diameter of the elbow, the deformation process of mould blank control, the metal flow in the arc compressed, compensation due to expanding and reducing other parts of thin thus, the uniform wall thickness of pipe elbow. The other is a stamping, stamping of stainless steel pipe elbow is the earliest to forming process for the production of large quantities of seamless elbow, elbow now commonly used in the production of specifications have been replaced by hot method or other molding process, but in some specifications of the stainless steel tube bend in production quantity and the wall thickness is too thick or too thin. Before stamping, the stainless steel tube blank is placed on the lower die, the inner core and the end die are loaded into the tube blank, and the upper die moves downward to start pressing, and the stainless steel pipe bend is formed by the constraint of the external die and the supporting role of the internal model. Source: China Stainless Steel Elbow Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)