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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)

Stainless steel elbow is a kind of elbow pipe with wide application style, rich angle and composition, and has a very good competitive advantage. Due to the existence of a thin and dense oxidation protection film on the surface of stainless steel, stainless steel has strong corrosion resistance in various water environment, even in the soil. So the elbow pipe made of stainless steel is also suitable for many water quality environments, so we only need to disinfect the water quality without multiple control of water quality, which can effectively save costs. And when using this elbow pipe, there will be no corrosion and excessive seepage. It can ensure the purity and health of the water, avoid the two pollution of the water quality, and also wash with the high speed water flow up to 30 meters per second. The advantages of stainless steel, the high connection strength, strong anti vibration, the connecting parts one-time do firmly and effectively prevent joint loosening, installation is very convenient, and the set of operations without welding wire and stainless steel elbow, long service life. According to the actual corrosion test data, the service life of stainless steel elbow can reach up to 100 years, and stainless steel elbow is not normally maintained when used normally, so its cost performance is very high, and its running cost is relatively low, which is obviously cost-effective. Because the stainless steel elbow has the advantages of watertight, no burst, fire prevention, earthquake resistance and so on, it is very reliable in safety performance, and its thermal insulation performance is good, so it is very suitable for transporting hot water. Stainless steel elbow with connecting reliable safety, convenient construction, sanitation and environmental protection performance, flow pressure loss is small, the system compatibility, can be installed and concealed, free maintenance, economic performance, wide application range, suitable for hot and cold water, drinking water, heating, air conditioning, fire and gas etc. civil low-voltage fluid transport, can also be used for low pressure liquid medicine, beverage, food, chemical industry, transportation. The on-site installation of the stainless steel elbow is very convenient. The installation of 1/3, only welded pipe fittings or wire, can shorten the time of work and reduce a large amount of consumption, and can also prevent leakage of water. In connection with the elbow, the elbow should be controlled and used according to a certain way and principle, with excellent installation characteristics and value. Stainless steel elbows can be used in different fields. Good characteristics and advantages promote continuous promotion and progress, enrich and show good value and function, and do not damage the value in construction. Generally speaking, the stainless steel elbow has been widely applied in many fields and industries. It can ensure the safety and pollution-free of water quality, so that it can meet various requirements.

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)

The common metal bellows are basically made of thin – walled stainless steel welded pipe. It can be used to transport various kinds of industrial gases, such as water, oil, medicine and other fluid medium. It can play an important role in reciprocating movement of pipeline, absorption of heat expansion system, absorption of vibration and adjustment of piping center. It features five main aspects, the first is convenient for construction, because the stainless steel corrugated pipe is a thin-walled tube, total weight, reduce the construction load and construction time greatly; secondly is the corrosion resistance is high, because the main body of the corrugated tube is made of 304 stainless steel or 316L stainless steel, and both use stainless steel joint or the carbon steel joint, excellent sealing performance and good corrosion resistance; stainless steel corrugated pipe has good pressure resistant performance; the materials of various kinds, even with the needs of users and customization; and stainless steel bellows and beautiful appearance, can be. The stainless steel bellows are based on the different wave types, including two kinds, which are circular corrugated tubes and spiral bellows. The pattern of the ring bellows is a tubular shell with a closed circular ring, which is formed in series between the wave and the wave. Circular bellows can be processed by seamless steel pipe or welded pipe. Limited to the processing technology, the length of the single tube is generally shorter than the spiral bellows. But the advantage is that the elasticity is better and the stiffness is low. The spiral corrugated tube is a corrugated tube with a spiral shape. There is a spiral angle between the two adjacent waves. All corrugation can be connected by a spiral line. The stainless steel corrugated soft tube according to use can be pided into metal bellows, bellows, bellows tube heat exchanger, diaphragm and Hengchang metal hose etc.. Metal bellows are mostly used to compensate for pipeline thermal deformation, shock absorption and pipeline settlement and deformation, etc., which are widely used in petrochemical, aerospace, power, metallurgy and other industries. A tubular elastic sensitive element that is connected in a folding and telescopic direction with a foldable wrinkle piece. The opening end is fixed and the seal end is in free state. It is the use of auxiliary spiral spring or reed to increase elasticity. At work, the length of the stainless steel tube is extended in the direction of the internal pressure, and the displacement of the active end can be caused by the pressure. The active end leads the pointer directly to indicate the size of the pressure. Bellows are usually combined with displacement sensors to form pressure sensors that output electricity, and sometimes used as isolation elements. Because of the stretch of ripple tube for volume changes greatly, so the response speed of the Bourdon tube below. The bellows are suitable for measuring low pressure. Source: China Stainless Steel Bellows Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

The performance of duplex stainless steel is generally strong, but it also has weaknesses. Especially, the weakness of high alloy duplex stainless steel containing high amounts of chromium, molybdenum and nitrogen is obvious. One is thermal processing performance, the deformation temperature in thermal processing, because the two microstructure of duplex stainless steel in strength, plasticity and the deformation behavior of different has the difference, it will reduce the thermoplastic properties, and thermoplastic decline will lead to thermal processing performance of duplex stainless steel worse. The other is the cold forming properties. The cold forming properties of the duplex stainless steel are less than those of the chromium nickel austenitic stainless steel, and are lower than some chromium containing ferritic stainless steels. This is related to the low yield strength, large deformation resistance, low elongation, large anisotropy, R value (plastic strain ratio) and n value (cold working hardening coefficient) of duplex stainless steel. Therefore, the duplex stainless steel is usually not suitable for the use of strict cold forming (such as deep drawing). For pipe and tubesheet expansion technology, we must use the larger external force to cause the steel tube yield, so that we can successfully complete the expansion joint operation, in addition, it can also make cold bending, but the resilience is higher. The following features of the lower double phase stainless steel are introduced. The first point is that the yield strength of duplex stainless steel is nearly twice as high as that of austenitic stainless steel, so the amount of deformation needed to be used is lower than that of the latter. When the cold rolling is done, the proper speed and delivery must be selected, so as to reduce the uneven longitudinal wall thickness and rolling. The rate of reducing the surface of the steel tube should not be too large when it is cold drawn. The second point is the middle of the pipe softening using continuous roller hearth type heating furnace and heat treatment furnace duplex stainless steel (water cooling device with exit), do not use electric contact heating, which is not easy to control the temperature, and the heating speed is very fast, easily lead to overheating, the ferrite microstructure content exceed the standard, especially in the rolling of thin walled tube, if the control is not good, it is easy to form bamboo like uneven wall thickness, even if the wall thickness is not too mean. In electric contact heating, thin wall parts rapid warming, cause local overheating, will greatly increase the amount of ferrite, and even the formation of single-phase coarse ferrite, reduced corrosion resistance, acid pickling process after when the site is prone to local pickling, resulting in damage to scrap of duplex stainless steel tube. The third point is the solid solution treatment of finished duplex stainless steel pipes, which is the key link. It not only eliminates the residual stresses in the finished products, but also ensures the proper two phase ratio and the surface quality of the finished products. During heat treatment, we should pay attention to the uniformity of material temperature and enough holding time, so as to avoid stress corrosion caused by insufficient solid solution and high residual stress on the surface of steel pipe. Finally, for the steel pipe, which is mainly used for stress corrosion resistance, the delivery of the solid solution in the pickling state is needed to avoid the abrasive delivery. When the pipe surface is distributed with small cracks and folding defects, when the whole tube is needed to abrade, the steel pipes after grinding must be treated again after solid solution and acid washing. The main reason is that the tangential stress in the residual stress produced by grinding is the main stress to produce SCC damage. Source: China Duplex Stainless Steel Pipe Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

When storing stainless steel plate, it should be placed on a special storage rack. The storage rack should be wood or surface painted carbon steel support or underlying rubber pad, so that it can be separated from other metals such as carbon steel and so on. When storing, the storage location shall be conveniently hoisted and pided into other materials storage areas, and there must be some protective measures to prevent dirt and oil contaminants from polluting the stainless steel. The hoisting of stainless steel plate, to use special sling, sling, such as special clip, prohibit the use of wire rope to avoid scratching the surface, but also in the lifting and placing, try to prevent shock bump cause scratches. When transporting stainless steel materials, we should use the means of transportation to keep the material clean and isolated, not to drag and drag, and not to be scratched and hurt. It is necessary to pay attention to the processing of stainless steel materials. First is the processing area, and the processing area of the stainless steel parts is relatively fixed. Isolation measures should be used for the platform of stainless steel parts, such as rubber pads. Management and processing stainless steel production should be strengthened to prevent damage and pollution of stainless steel. The second is the blanking, the cutting of stainless steel parts by cutting or plasma cutting, sawing and so on. The third is cutting, in shearing, to be separated from the support, and the hopper should also be laid on rubber pads to prevent the scratch of stainless steel material. The fourth is to clean the slags after plasma cutting. In the process of batch cutting, the finished parts should be cleaned in time so as to prevent the pollution of the workpiece. When cutting the material, the clamp should be protected by the rubber, and the oil and residue on the stainless steel workpiece should be cleaned after sawing. When machining stainless steel, stainless steel parts should also be protected when machining, such as vehicle and milling. After finishing operations, oil stains, iron scraps and other debris should be cleaned up. In the process of stainless steel plate forming, in the process of rolling and bending, it is necessary to use effective methods to prevent the scratch of the surface of stainless steel parts. Source: China Stainless Steel Plates Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

Stainless steel pipe, as a very common metal material, is widely applied due to the rapid progress of material processing technology. These excellent machining processes help to enhance the performance of stainless steel pipes and meet the needs. But after a series of processing processes, especially after heat treatment, the stainless steel pipe must be cooled. The cooling process is very important for the use of stainless steel pipes, because once any part of the process is wrong or wrong, it will lead to problems affecting the quality of stainless steel pipes, because we should pay special attention to several problems when cooling stainless steel pipes. The first is the degree of stability of stainless steel pipe cold austenitic high hardenability is also great, even if the air cooling can be obtained martensite, but air cooling can cause the surface of stainless steel tool products formed oxidation, and may precipitate eutectoid carbide now, so try not to use air cooling process. For large and complex structure of the stainless steel pipe, in order to reduce the deformation and cracking degree, can do a pre cooling treatment when quenching, but need to control the time, usually according to control the shape of the stainless steel pipe in a few seconds to tens of seconds, but the premise is not two carbon compounds can be precipitated and hard to reduce tool hardness and red, also can not form such as pitting corrosion. The third is that the grading quenching temperature should not be higher than 650, to avoid the transition of pearlite and the precipitation of carbides. The fourth is to take into account that the transformation temperature of the lower bainite is 320-250 degrees C, and the fastest transition temperature is 260 to 300 degrees. So the production is 260-280 to 300 hours. Because the retained austenite temperature after isothermal quenching is more and more stable, four tempering is required. The fifth is the high temperature quenching to 580 to 620 DEG C neutral salt bath, can not use 500 to 550 DEG C nitrate graded cooling, it is the cause of nitrate will hot forming tool oxidation and corrosion, and even the sharp knife burning. The last point is that the stainless steel pipe should be vertically placed in the cooling medium during the quenching operation so as to reduce the deformation of the stainless steel pipe. Source: China Stainless Steel Pipes Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

Because stainless steel plate has high yield point, strong hardness and cold hardening effect, there are many characteristics to be noticed when doing deep drawing. First, because the thermal conductivity of stainless steel plate is weaker than that of ordinary low carbon steel, the deformation force is high. Secondly, when drawing deep, the plastic deformation of the stainless steel plate is hardened and the sheet drawing is easier to wrinkle and the edge pressure is stronger. The third is the springback caused by bending and reverse bending at the fillet corner of the drawing die, which usually causes concave deformation on the side wall of the product, which results in higher dimensional accuracy and shape requirement. The last one is that the stainless steel plate is easy to produce the bond in the drawing process. And how do you solve the problem? The first step is to choose the working parts of die materials better, in order to solve the problem of tumor bond practice shows that, with cast aluminum bronze, aluminum bronze, anti sticking effect is better, the use of tungsten carbide alloy die manufacturing than the service life of the die with Cr12Mov soft nitriding improved several times, also won’t stick to die; and such as the use of code 3054 alloy cast iron, as long as the flame quenching on the surface of the mould, mold will not appear on the surface of tumor adhesion. The surface of the working part of the mold should also be processed. Because the surface quality of the stainless steel drawing die is very high. The lower surface roughness can reduce friction and enhance the adhesion resistance. Therefore, to reduce the surface roughness of the die, the number of molds will also be reduced, which helps to improve the service life of the die. But also for the lubrication of the process, from the characteristics of stainless steel drawing to understand tumor is due to generation of bonding sheet and the mold have direct contact, so the choice of primary point lubricant or coating agent is in sheet deep drawing process of lubricating film can not break from first to last for lubrication. A good effect can be obtained by adding a certain proportion of additives or using solid lubricants in the lubricants. This is mainly to enhance the lubricating ability of lubricant on the surface of metal compounds, sulfur, phosphorus and chlorine to form at high temperatures and the metal surface chemical reaction, formation of iron sulfide, chloride, to strengthen the oil film strength and enhanced adsorption capacity, better lubrication and surface mold products. Solid lubricants are filled into small pits on the metal surface, so that the dry friction contact points are reduced to a minimum. In addition, solid lubricants are highly stable, and can also play a lubrication role at high temperature, and die bonding is not easy. In general, different proportions are selected according to the deformation degree of the product and the actual situation in the production. Source: China Stainless Steel Plates Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

Stainless steel pneumatic valve is made of stainless steel material with pneumatic actuator Pneumatic ball valve, although stainless steel is very much, but the most common stainless steel ball valves are basically made of 304 stainless steel, 316 stainless steel, the characteristics of the pneumatic ball valve is a strong corrosion resistance. A stainless steel pneumatic ball valve closes tightly only with a 90 degree of gas rotation and a very small moment of rotation. The ball valve is characterized by its compact structure, easy operation and maintenance. The stainless steel pneumatic ball valve is widely used in pipelines conveying water, solvent, acid and natural gas. It is also suitable for pipeline transport in medium, such as oxygen, hydrogen peroxide, methane and ethylene, in the medium of bad working environment. More types of stainless steel ball valve, in the form of the structure can be pided into three kinds, the first is the stainless steel floating soft sealing valve, also called floating pneumatic ball valve, stainless steel ball valve ball is floating in the medium under pressure, the ball can generate some displacement and pressed the sealing surface in the outlet end, and to ensure that exit seal. The structure of the stainless steel floating ball valve is relatively simple, and its sealing performance is relatively good. However, the load that the sphere bears the working medium is all passed to the export seal ring, so we need to consider whether the material of the sealing ring can withstand the working load of the ball medium. This structure is mostly used in medium and low pressure stainless steel ball valves. The second kind is the stainless steel fixed ball valve, also called the fixed ball pneumatic ball valve. The ball of the stainless steel ball valve is fixed and does not move after being pressed. The stainless steel fixed ball valve has the floating valve seat. The valve seat moves after the pressure of the medium, so that the seal is pressed on the ball to ensure the seal. In general, and the sphere of the upper and lower shaft with bearings, operating torque, suitable for use in high pressure and large diameter of the valve. The third kind is the stainless steel ball ball valve, also called the elastic ball pneumatic ball valve, the ball of the stainless steel ball valve is elastic. The ball and seat gasket are made of metal material. The sealing ratio is very high. The pressure of the medium can not meet the requirement of sealing. We must exert external force. This kind of valve is suitable for high temperature and high pressure medium. The elastic ball of the stainless steel is an elastic groove on the lower end of the inner wall of the sphere, thus getting the elasticity. When the channel is closed, the wedge head of the stem is used to make the sphere open and the seat press tight to get the seal. Before rotating the ball, the wedge head is loosened first, then the sphere is restored to the original shape, resulting in a small gap between the ball and the valve seat, which can reduce the friction and operation torque of the sealing surface. Source: China Stainless Steel Pneumatic Ball Valves Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

The surface of hot-rolled stainless steel plate usually has a thick oxide layer. If chemical oxidation is used to remove oxide layer, it will not only increase pickling time, reduce pickling efficiency, but also increase the pickling cost too much. Therefore, to use other methods to treat the stainless steel plate as an auxiliary process, there are three main pretreatment processes for pickling. The first is the shot peening process, this is a kind of mechanical removal way at the present time most frequently used, it is the principle of using shot peening equipment ejected fine particles of the shot to hit the surface of stainless steel plate, stainless steel plate in order to get rid of the thick oxide layer. After shot peening, some oxide layers will be removed, and the remaining oxide structure on the stainless steel plate will become loose and discontinuous, which is very beneficial for later pickling. The second is alkali leaching process, which includes two kinds of alkaline leaching with oxidation type and reduction type alkali leaching. The oxidized alkali leaching is also called the “salt law”, its mechanism is after alkali treatment for stainless steel oxide refractory iron chromium spinel (FeCr2O4) modified into alkali soluble CrO3, and because of changes in the volume and structure of oxide layer, the oxide layer falling off. Reduced alkali leaching is the strong reducing agent NaH, the oxide of iron, nickel, chromium and other refractory metal oxide or metal oxide reduction becomes low, and let the oxide layer break off, shortening pickling time and enhance efficiency. In the process of oxidizing alkali leaching, a certain degree of Cr6+ pollution will be formed. The reduction type alkali leaching can remove the problem of Cr6+ pollution, and the key material is NaH. Domestic use Potassium Permanganate oxidized alkaline leaching process, while the foreign countries mostly use the leaching of alkali reduction. The third one is neutral salt electrolysis, which takes Na2SiO4 aqueous solution as electrolyte. The stainless steel plate passes through the electric field between cathode and anode, changing cathode and anode continuously, and removing the surface oxide layer after current action. The mechanism of electrolysis of neutral salt, which is oxidized to higher soluble ions by chromium, manganese and iron oxide in the insoluble oxide based, so that the oxide layer is dissolved; second is based on the stainless steel substrate is oxidized to metal ions, so that the spallation of the oxide adhered on the surface of the stainless steel plate. In general, the most common use now is the neutral salt electrolysis process. These pretreatment processes can remove the oxidation layer on the surface of the hot rolled stainless steel plate and reduce the load produced during the pickling. Source: China Stainless Steel Plates Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

In the building materials, the stainless steel round steel and the screw steel are the common forms of address for different kinds of steel bars. The difference between them is quite obvious, mainly five points. The first is the difference in shape. The outer surface of the stainless steel round steel is very smooth, while the outer surface of the screw steel has a spiral rib. Secondly, the production standards of both are different. In the modern standard, stainless steel refers to HPB235 steel, the production standard is based on the “hot-rolled smooth steel reinforced concrete and steel”, usually refers to the HRB335 and HRB400 grade steel, the production standard is based on “the reinforcement of concrete hot rolled ribbed bar”. The third point is that they are different in their strength. The design strength of stainless steel round steel is 210MPa, while the strength of rebar is higher than that of stainless steel round bar. The design strength of HRB335 is 300MPa, and the design strength of HRB400 is as high as 360MPa. The fourth point is that the steel is different, that is to say, the chemical composition in the steel body is different. The stainless steel round carbon is carbon steel, the steel is Q235, the rebar is low alloy steel, the HRB335 grade reinforcement is 20MnSi (20 MN SI), and the HRB400 grade reinforcement is 20MnSiV or 20MnSiNb or 20MnTi. It is because the chemical composition is different, so the physical and mechanical properties of the two are different. The better performance of cold-formed stainless steel, can hook 180, screw steel can be just 90 degrees straight hook, stainless steel weldability is good, as long as the use of ordinary carbon welding line, screw steel must use low alloy steel electrode; the toughness and anti fatigue properties etc. than the excellent stainless steel round bar. Steel reinforced concrete is often used to build facilities, material is generally low alloy steel grades is generally 16Mn (16 Mn low-alloy steel), or 45 carbon just, yield strength are higher than 350Mpa, the tensile strength was less than 500Mpa, compared with the ordinary low carbon steel stainless steel round up very much, one thread the strength of the steel after heat treatment of the low carbon stainless steel round steel is nearly twice as high or even more. Because the surface has a thread shape, it can increase the bond with the concrete. The concrete member should choose the thread steel first with the longitudinal reinforcement and the stirrup. So in general, because steel is a kind of low alloy steel, the price than the low carbon stainless steel round steel is high, the construction units from the ordinary civil construction of affordable angle positioning for reducing the quality of the project, will instead use low carbon stainless steel instead of steel. While some large key projects, usually in bribe related personnel, with stainless steel instead of steel rebar to “substitution”, so as to reduce the construction cost. From the design perspective, because members without stirrups give principal stress support, the main role is to keep in shape and position, and because the stainless steel round bar surface is relatively smooth, the strapping easy positioning accuracy, so in addition to longitudinal reinforcement, can be used as a steel reinforced stainless steel round bar. But the longitudinal bar must be completely threaded steel. Source: China Stainless Steel Pipes Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

As a special kind of special steel with excellent performance, stainless steel is widely used in the production and life of people. Usually the stainless steel material in molding process, most of them are subject to various heat treatment processing, this time such as annealing, quenching, welding and forging process, it will form a layer of black oxide on the surface of stainless steel, the oxide skin will not only affect the appearance quality of stainless steel, will have a negative impact the stainless steel machining process, so in the following processing prior to this layer of oxide skin removing. The oxide scale of stainless steel is mainly composed of NIO2, Cr2O3, FeOOCr2O3, FeOOCr2OO3Fe2O3 and other dense spinel oxides. It is very firmly combined with the matrix of stainless steel and is hard to remove by ordinary acid washing. In addition, the difficulty of removal also varies with the steel and the manufacturing conditions. Therefore, it is of great practical significance to grasp the methods of various stainless steel oxide pickling and to choose the production process reasonably. Below is a simple way to remove the acid washing of the oxide skin. The first is the three acid washing method, the acid is sulfuric acid, nitric acid and hydrochloric acid. It is a more effective acid cleaning method for removing the stainless steel oxide skin. The proportion of the three acids is probably 15%-20%H2SO4, 5% ~ 7%HCl, 5% ~ 7%HNO3, and the pickling temperature of three acids should be kept at about 70-800 degrees. The specific pickling time should be decided by the composition and condition of stainless steel oxide scale, usually 20 to 50min. The three method can successfully remove acid stainless steel oxide, but because the pickling process will precipitate a lot of nitrogen dioxide, which will worsen labor conditions, environmental pollution. In addition, the acid washing process is easy to form the phenomenon of acid washing. The second method is nitric acid and hydrofluoric acid pickling, this kind of acid washing is a better way of stainless steel pickling. The commonly used proportioning method is 4%-6% hydrofluoric acid and 8%-12% nitric acid. The temperature of the acid is 50 to 600 degrees. The pickling time depends on the oxide scale of the stainless steel surface, usually 20 to 40min. The operation process must be looked over diligently to avoid pickling. In fact, the acid pickling speed is faster, the operation is easy and the quality is good. However, hydrofluoric acid is highly toxic, and requires better ventilation and wastewater treatment. The third is alkali cooking, also called the acid washing compound method. In order to solve the weakness of tricarboxylic acid method, the compound method of alkali boiling and pickling can not only optimize the quality of pickling, but also reduce the consumption of metals. Alkali cooking can loose oxide, then remove the oxide using acid washing. Most of the ingredients in the alkali boiled liquid are the mixture of sodium hydroxide and sodium nitrate, with a ratio of 8:2. The temperature of alkali boiling is controlled at 500 to 550 degrees C. The time of alkali cooking is related to the steel, specification, quantity and oxidation skin state of stainless steel, usually from 30min to 1.5h. Stainless steel material after alkali boiling to immediately immersed tank burst to the scale, then the use of three acid washing to remove oxide. Source: China Stainless Steel Pipes Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)