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Austenitic stainless steel on weak base, such as hydroxide and organic compounds such as ammonia, which the organism and aliphatic amine aniline with excellent corrosion resistance, 304 stainless steel can be used in the ammonia distillation apparatus and some types of amination reaction. By sodium hydroxide solution corrosion test, the stainless steel in the performance of alkali solution, 302 and 304 stainless steel in concentration below 50% NaOH solution, under the temperature 104 ℃, generally only mild corrosion. At higher temperatures and concentrations, erosion tends to be severe. Under various stress effects, the corrosion cracking of the stress can occur in the solution of the hot hydroxide solution or the potassium nitrogen oxide solution. When a hot metal surface is eroded by a dilute solution, it can also be corroded by the vaporization of hydroxide. Source: China Steel Pipe Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

Additives have the effect of inhibiting corrosion and increasing light. It can form a complicated adsorption layer on the surface of stainless steel, activate the microconvex point on the surface of the parts, and blunt the microconcave point to make the polishing effective. Refers to this kind of additive of polishing fluid viscosity regulator, corrosion inhibitor, etch, activator and antifoaming agent, because they exist, chemical polishing can smoothly, surface polishing effect. The additives include inorganic salt, organic salt, organic compound, surfactant, etc. (1) inorganic salt. They are mainly sulphate, phosphate, nitrate, acetate, molybdate, chloride, fluoride, etc. (2) organic compounds are mainly glycerin (glycerin), if ding, organic amine, gelatin, dextrin, sodium dodecyl sulfate and thiourea, polyol, cellulose ether and polyethylene glycol, chlorine alkyl which the organism, halogen compounds, sulfosalicylic acid, azo dyes, etc. (3) the light agents that have a strong effect are benzoic acid, salicylic acid, sulfonic acid, benzene diphenol, and fluoroseason ammonium salt. The type and concentration of additives are determined by the quality of polishing, and the average dosage is 0.1% ~ 1.0%, which is the composition and temperature of the polishing liquid. The sulfur vein is easily decomposed in high temperature, so it should not be used at high temperature. Some additives, such as collagen, dyes, salicylic acid, hydroquinone, etc., should be pre-arranged in saturated solution and in the polish. As a inhibitor, it is suitable for the use of 1 ~ 5g/L, which is used as a inhibitor of butyl dimethylamine (dimethylbenzene) and ulothene (CH2) 6N4. As a light agent, chlorine alkyl, halogen, and sulfonic acid are used for 3-5g/L. The mixture of cellulose ether and polyethylene glycol is 20 ~ 40g/L. Source: China Flanges Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

The 904L stainless steel number is 00cr20ni25m02.5cu, which is a highly alloyed super-austenitic stainless steel with low carbon content. In dilute sulphuric acid, there is a good corrosion resistance, and the addition of copper makes it very resistant to acid, designed for harsh conditions. So this kind of stainless steel is used mainly for the manufacture of corrosion resistant pressure vessels. The elements of 904L are mainly composed of elements such as Cr and Ni, which are difficult to process, and the machining is poor, and the main reasons are as follows. 1) 904L stainless steel is more powerful than other kinds of stainless steel. Because 904 l although not high hardness (70 ~ 90 HRB), but has good plasticity and elongation of 40% or higher, a reduction of 50% or more, the tensile strength at б b p 490 mpa, yield strength at 0.2 or greater б 216 mpa, and large plastic deformation in the process of cutting, the cutting force increases. 2) the thermal conductivity is low. Thermal conductivity of 904 l stainless steel (20 ℃) is 12.9 W/(m K), low thermal conductivity, only a quarter of the 45 steel (45 steel thermal conductivity is 47.5 W/(m K)). Thermal conductivity is one of the main factors influencing the cutting heat conduction, the lower the thermal conductivity of the material processed, heat was taken away by the chip and workpiece is less, while the accumulation of heat on the cutting tool, the tool wear easily. 3) it is easy to be a cross product. Due to the 904 l stainless steel toughness is big, so in the process of cutting and cutting tool materials, strong affinity, when cutting tool rake face and chip of the underlying strong friction in metal, under the action of high temperature and high pressure will produce adhesion phenomenon, generate the devolop tumor, is not easy to obtain high surface roughness requirements of machining surface. 4) shavings are not easy to bend and break. 904L stainless steel has a high elongation rate, so it is not easy to bend and break in the cutting process. If appropriate measures are not taken, it will affect the normal process of the cutting process and can easily scratch the surface and even cause the cutter to collapse and damage. Due to the above characteristics of 904 l stainless steel, with conventional cutting tools and the traditional method of cutting, even select a very small cutting parameter, cutting tool is still easy to wear and tear, low machining efficiency, and it is difficult to achieve pattern required by the surface roughness of workpiece and machining accuracy. Source: China 904L Flanges Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

Steel heating to 1050 ~ 1100 ℃, then rapid cooling in water, to get a single-phase austenitic organization, this process is called solution treatment. Solution treatment temperature should choose according to the carbon content of stainless steel, usually take limit at high carbon content, carbon content lower limit, but the temperature is unfavorable and exorbitant, both also shoulds not be too low. Temperature is too high, will appear a large number of ferrite, and make the steel coarse grains, such bad, not only make the fabrication procedure and reduce steel uniform corrosion resistance. From the point of view of intergranular corrosion, the higher the heating temperature, the greater the degree of supersaturation of austenite, after precipitation of chromium carbide reheat temperature range, chromium carbide precipitation process is more intense, to increase the susceptibility to intergranular corrosion of steel. If the temperature is too low, the composition of the steel and the sufficient dissolving of carbide are not sufficient to achieve the effect of solidification. Solution treatment should prevent surface carburizing, when heating for carburizing steel increases, the susceptibility to intergranular corrosion of the valve, the valve body, valve seat, a kind of direct contact with the working medium of the so-called internal parts, the performance requirements of general corrosion and intercrystalline corrosion resistance requirements is much taller than other stainless steel valve parts, therefore, internal parts of the surface of the solution treatment especially need to pay attention to carburizing. When heated, usually in neutral or slightly oxidizing atmosphere. Processing or machining allowance for after heat treatment is no longer a small parts, before heating furnace should be paid attention to cleanliness, and remove the oil on the surface of the parts, to prevent the dirt decompose when heated, make parts surface carburizing. After the solidification process, the strength of the steel increases with the increase of carbon content. However, the strength of this kind of steel is not high in general, compared with the treatment of sensitization and stabilization. Therefore, the curing process is also the maximum softening treatment. Solution treatment to dissolve carbide at high temperature in a steel is heated, and for the next fast cooling and fixed in austenite, so the corrosion resistance of steel with the highest of solution treatment, for not including 18-8 of titanium or niobium steel, solution treatment is one of the important means to prevent intergranular corrosion. Solution treatment of heat preservation time shoulds not be too long, it have close relationship with the diameter and thickness of the parts, the material of 25 mm in diameter, according to can according to commonly 2 ~ 3 minutes/mm to calculate time of heat preservation. Commonly used solution treatment, the cooling system of water-cooling, but for the cover sleeve, sleeve seat and jacketed valves outer jacket and thin wall parts and air cooling can be applied. Source: China Valves Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

Physical properties of stainless steel Comparison of physical property data of stainless steel and carbon steel, carbon steel, the density is slightly higher than that of ferritic and martensitic stainless steel, and slightly lower than the austenitic stainless steel; resistivity by carbon steel, Ferritic, martensitic and austenitic stainless steel sort increment; linear expansion coefficient of size sorting is similar, austenitic stainless steel and carbon steel minimum; carbon steel, Ferritic and martensitic stainless steel magnetic, austenitic stainless steel is not magnetic, but the cold hardening generated into martensite transformation will produce magnetic heat treatment, available method to eliminate this martensite and restore its non-magnetic. Austenitic stainless steel compared with carbon steel, has the following characteristics: 1) the high rate of electric negative is about 5 times of that of carbon steel. 2) the coefficient of linear expansion is 40% larger than that of carbon steel, and the coefficient of linear expansion increases correspondingly as the temperature increases. 3) low thermal conductivity, about 1/3 of carbon steel. Mechanical properties of stainless steel Austenitic stainless steels are similar to most other metal materials, and their tensile strength, yield strength and hardness increase with decreasing temperature, while plasticity decreases with decreasing temperature. Its tensile strength increases at a temperature range of 15~80 degrees C, which is even. More importantly, as the temperature decreases, the impact toughness decreases slowly, and there is no brittle transition temperature. Therefore, stainless steel can maintain sufficient plasticity and toughness at low temperatures. Heat resistance of stainless steel Heat resistance refers to the high temperature, both antioxidant or gas medium corrosion resistance, namely thermal stability, while in high temperature double enough strength, namely heat intensity. Source: China Steel Pipe Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

The first mode of production: the tube billet (plate, strip) is formed directly into the pipe, and its main process is the forming, welding and sizing of plate tape. Features: low production process, simple engineering process, short production cycle, low precision of product. The second mode of production: the tube billet welding (plate, belt) direct forming into a certain size of steel pipe, and then after cold drawn or cold rolled into a finished product steel tube, known as the DOM welded steel pipe. Its main process is forming, welding, sizing, cold rolling or cold drawing (with a mandrel or no mandrel), or continuous cold drawing (that is, the welding, cold pulling joint production line). Features: the production procedure, the technological process and production cycle is long, covers an area of big, dimension precision products, both inside and outside surface is bright and clean, good mechanical properties and microstructure of state. The third kind of mode of production: the tube billet welding (plate, belt) direct forming into a certain size of steel pipe, into the continuous cold sinking into a finished product reducing mill for steel. Its main process is forming, welding, continuous cooling reduction. Features: the production process is compact, the process flow is concise, the production efficiency is high, the specification scope changes fast, the production small diameter and thin wall electric welding steel pipe. Source: China Steel Pipe Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

(1) preface: It is well known that stainless steel has its unique strength and high abrasion resistance and its excellent anti-rust properties. It is widely used in chemical industry, food machinery, electromechanical industry, household electrical appliance industry. At present, a lot of entering the home decoration industry, giving people the feeling of luxuriant nobility. The application of stainless steel will be more and more widely available, but the application of stainless steel will largely determine its surface treatment technology. Let me talk about the surface treatment of stainless steel for discussion. (2) introduction of stainless steel varieties: Stainless steel usually contains high quality metallic elements such as chromium (CR), nickel (NI), molybdenum (MO) and titanium (TI). Common stainless steel is chromium stainless steel, which contains CR > = 12%. Nickel chromium stainless steel contains CR > = 18%, including NI > = 12%. From the stainless steel metallographic structure: the austenitic stainless steel, for example: 1CR 18 NI9TI, cr18ni11nb. Martensitic stainless steel, such as CR17, CR28, etc. It is commonly referred to as non-magnetic stainless steel and magnetic stainless steel. (3) surface treatment of stainless steel: At present, the surface of stainless steel surface is treated with white treatment. (2) the surface mirror is polished. (3) surface shading treatment. In the process of processing, the stainless steel is processed by the coil plate, the edge, the welding, or the handling by the agent. The hard, black, black oxide skin is mostly NICR2O4 and NIF two, the EO4 component, which was previously used in a strong corrosion method with hydrofluoric acid and nitric acid. But this method is costly, polluting the environment and harmful to the human body. The corrosion was larger and gradually eliminated. There are two methods for the treatment of this type of oxidation: (1) the use of the blasting method. (2) adopt the chemical method. It is used to wash the cleaning liquid with an inorganic additive with non-contaminated pickling paste and normal temperature. Thus, the purpose of whitening the stainless steel. It basically looks like a look. This method is suitable for large and complex products. Stainless steel surface gloss treatment: According to the complexity of the stainless steel products and user requirements is different respectively by mechanical polishing, chemical polishing and electrochemistry polishing method to achieve mirror Shi Guangze. Here are three ways to make a choice: Table 1 Project method advantage Disadvantages Applicable Products Remarks Mechanical polishing Good leveling, bright Labor intensity, serious pollution, complex pieces difficult to process, shiny decline, high investment and cost Simple parts, medium and small products, complex parts can not be processed The whole product gloss is not consistent, shiny to keep time is not long Chemical polishing Less investment, complex pieces can throw, high efficiency, fast Lack of brightness, polishing fluid to humidification, gas spill, the need for appropriate equipment Complex products, low brightness requirements of the product can be used Small batch processing is more cost-effective Electrochemical polishing Up to the mirror glossy, long-term maintenance, process stability, less pollution, low cost, good pollution prevention One-time investment large, complex parts to be installed equipment, auxiliary electrodes, mass production to cool Dirt products, requiring a long time to keep the mirror light, bright products Stable process, easy to operate, can be widely used Stainless steel is not only used in the color of stainless steel, it also increases the color of the product, and increases the durability and wearability of the products. The stainless steel coloring method has the following: (1) ionic deposition oxide or oxide. (2) high temperature oxidation. (3) chemical oxidation. Electrochemical oxidation. (4) the gas phase cracking method. A brief description of various methods is summarized as follows: (1) ion deposition oxide or oxide method, is put stainless steel workpiece in the vacuum evaporation plating in vacuum coating machine, such as: titanium plating hand watch case and band. It is usually golden. This method is suitable for mass production. Because investment is big, cost is high, small batch product is not economical. (2) the high temperature oxidation method is in particular molten salt, the workpiece stays in certain scope of process, the workpiece to form a certain thickness of oxide film, and present a different color. (3) chemical method is in particular solution, the color of the membrane, are formed by chemical oxidation generally have used “by law”, but need to be able to guarantee a batch of product colour and lustre is consistent, must be controlled by reference by telex. (4) electrochemical method, which is used in a particular solution, by electrochemical oxidation. (5) gas phase cracking, which is more complicated, is less applied in industry. (4) description: This paper briefly introduces the method of surface treatment of stainless steel, which is specific to the requirements of the products and which method to choose. Depending on the product, the material and the surface requirements are different. Choose to implement the feasible work plan. Since the formula for the process is trade secret, it is not easy to write here, please understand. Source: China Stainless Steel Pipe Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

Allegheny Ludlum’s 317LXN™ is molybdenum-bearing austenitic stainless steel with greatly increased resistance to chemical attack as compared to the conventional chromium-nickel austenitic stainless steels such as Type 304. AL 317LXN™ alloy also offers higher creep, stress-to-rupture, and tensile strength at elevated temperatures than conventional stainless steels. The alloy has low carbon to provide resistance to sensitization during welding and other thermal processes. The combination of increased levels of molybdenum and nitrogen enhance resistance to pitting and crevice corrosion especially in process steams containing acids, chlorides and sulfur compounds at elevated temperatures. Nitrogen also serves to increase the strength of this alloy. This alloy is intended for severe service conditions such as flue gas desulfurization (FGD) systems.Information provided by Allegheny Ludlum Corporation. Table 1 ASTM A240 Chemical composition (wt%) Component Elements Properties Metric English Comments Carbon, C <= 0.030 % <= 0.030 % Chromium, Cr 17 – 20 % 17 – 20 % Iron, Fe 60 % 60 % as balance Manganese, Mn <= 2.0 % <= 2.0 % Molybdenum, Mo 4.0 – 5.0 % 4.0 – 5.0 % Nickel, Ni 13.5 – 17.5 % 13.5 – 17.5 % Nitrogen, N 0.10 – 0.20 % 0.10 – 0.20 % Phosphorous, P <= 0.040 % <= 0.040 % Silicon, Si <= 0.75 % <= 0.75 % Sulfur, S <= 0.030 % <= 0.030 % Corrosion resistance: 317LXN, 317LX and 317L stainless steel in the medium corrosive media in the more ordinary 304 stainless steel has a higher corrosion resistance, usually, 18-8 stainless steel does not produce corrosion of the environment, the stainless steel is not Mo Will produce corrosion, but strong oxidizing acids, such as nitric acid. In the sulfuric acid solution, 317LXN, 317LX and 317L are more resistant to corrosion than 304 stainless steel, and as the Mo content increases, the corrosion resistance increases. These three stainless steels can withstand corrosion at 49 ° C and 5% sulfuric acid. When the temperature is below 38 ° C, these three stainless steels also exhibit excellent corrosion resistance in higher concentrations of sulfuric acid. However, field tests are recommended to better assess the effect of specific operating conditions on corrosion behavior of the alloy. In the process environment containing sulphide-containing furnace gas condensate, these three stainless steels are more resistant to corrosion than the 316 stainless steel. In this environment, the concentration of acid will significantly affect the corrosion rate of corrosion and corrosion of the alloy, which should be carefully tested by field test corrosion of various alloys. Table 2 shows the uniform corrosion rates for 317LXN, 317LX and 317L strip samples in ASTM standard test solutions, and the values for 316L, AL-6XN and AL-276 alloys are also listed in the table for comparison. Test solution Corrosion rate MPy（mm/y） 316L 3317L 317LXTM 317LXNTM AL-6XN? AL276TM 20% Acetic acid 0.12 (<0.01) 0.48 (0.01) 0.24 (<0.01) 0.12 (<0.01) 0.12 (0.01) 0.48 (0.01) 45% Formic acid 23.41 (0.60) 18.37 (0.47) 11.40 (0.29) 11.76 (0.30) 4.56 (0.12) 2.76 (0.07) 10% Oxalic acid 48.03 (1.23) 44.90 (1.14) 46.68 (1.19) 35.76 (0.91) 10.92 (0.28) 11.24 (0.28) 20% Phosphoric acid 0.60 (0.02) 0.72 (0.02) 0.72 (0.02) 0.24 (<0.01) 0.24 (<0.01) 0.36 (0.01) 10% Sulfuric acid 635.7 (16.15) 298.28 (7.58) 255.00 (6.48) 157.80 (4.01) 84.36 (2.14) 13.93 (0.35) 10% Sulfite 71.57 (1.82) 55.76 (1.42) 25.08 (0.64) 15.60 (0.40) 24.00 (0.61) 2.64 (0.07) 50% Sodium hydroxide 77.69 (1.92) 32.78 (0.83) 69.18 (1.76) 85.68 (2.18) 15.96 (0.41) 17.77 (0.45) ASTM A262 B（FeSO2·H2SO4） 26.04 (0.66) 20.76 (0.53) 23.52 (0.60) 17.28 (0.44) 21.36 (0.54) 264.5 (6.72) ASTM A262 C (65%HNO3) 22.31 (0.56) 19.68 (0.50) 48.24 (1.23) 16.32 (0.42) 29.04 (0.74) 908.0 (23.06) ASTM A262E (Cu·CuSO4·H2SO4) pass pass pass pass pass pass The carbon content of these three alloys is less than 0.03%, low carbon content effectively improve their resistance to intergranular corrosion during welding or forging. 317LXN, 317LX and 317L stainless steel contain higher Cr, with better resistance to intergranular corrosion. However, it should be noted that prolonged exposure to the temperature range of 417-816 ℃, due to the precipitation of δ phase, will greatly reduce the corrosion resistance of these alloys, while the material may also become brittle. The higher N content of 317LXN delays the precipitation of δ and carbide precipitates. Table 3 pitting index of various alloys Alloy PRE 316 317L 317LXTM 317LXNTM AL-904LTM AL-6XN AL TEMP 625 AL276TM 25 30 34 38 36 48 52 69 As shown in Table 3, the high Mo high N significantly improved the pitting index (PRE) of the alloy, that is, the corrosion resistance of the alloy, the PRE value was based on the corrosion test results. The corrosion test found that CI-point corrosion performance, N is 30 times the effectiveness of Cr, is 9 times the Mo. The critical crevice corrosion temperature of stainless steels and nickel-based alloys measured according to the modified ASTM G48 B test method is significant (see Table 4). It can be seen from Table 4, with the austenitic stainless steel Mo and N content increased, the alloy critical crevice corrosion temperature also greatly improved. Table 4 the critical crevice corrosion temperature of various alloys Alloy ℃ 316 825TM 317L 317LXTM 317LXNTM AL-904LTM AL-6XN AL TEMP? 625 AL276TM －3 －3 2 18 24 20 43 45 55 317LXN, 317LX, 317L stainless steel in the acidic solution containing CI- or other halogen ions in the 316,304 type stainless steel has better resistance to corrosion and crevice corrosion, so the three kinds of stainless steel is often used for flue gas Desulfurization system (FGD). Table 5 shows the crevice corrosion test data for the various alloys in the simulated FGD solution. Table 5 Corrosion data of various alloys in simulated FGD test solutions Alloy Weightlessness（g/cm2） 24℃ （75°F） 50℃ （122°F） 70℃ （158°F） 317L 317LXTM 317LXNTM AL-6XN AL TEMP 625 AL276TM 0.0007 0.0000 0.0000 0.0000 0.0000 0.0000 0.0377 0.0319 0.0129 0.0000 0.0000 0.0001 0.0500 0.0462 0.0462 0.0266 0.0149 0.0004 According to ASTM G 48 B operating procedures, the test time: 72 hours Solution Ingredients: 7 vol% H2SO4, 3 vol% HCI, 1 wt% CuCI2, 1 wt% FeCI3 Antioxidant: In the atmospheric environment, Cr-Ni-Mo stainless steel has excellent oxidation resistance and low descending speed when the temperature is lower than 871 ~ 899 ℃. Manufacturing: 317LXN, 317LX, 317L stainless steel physical properties and mechanical properties similar to the conventional 316 and 304 stainless steel, which can be used in the same way as ordinary stainless steel manufacturing. Forging: the three kinds of stainless steel recommended forging temperature is 1150 ~ 1205 ℃, the final forging temperature of 927 ~ 955 ℃. Heat treatment: 317LXN, 317LX, 317L stainless steel can be in the temperature range of 1080 ~ 1175 ℃ heat treatment, and then according to the thickness of water or air cooling. The plates should be heat treated at 1150 ° C and 1170 ° C and then allowed to cool the material from red and white at an annealing temperature to black in 3 minutes. Hardness: These three kinds of stainless steel can not improve the hardness by heat treatment. Welding: welding with high alloy welding material to maintain the corrosion resistance after welding. When welding 317L stainless steel, the welding material should contain at least 6% Mo; welding 317LX and 317LXN stainless steel, the welding material should contain at least 8% Mo, such as the use of 625 alloy as a welding material. In the actual welding operation, if you can not use high matching welding materials, and can not be post-weld heat treatment and pickling, you need to carefully consider whether the self-welding weldment to meet the requirements of the process conditions. 317LXN, 317LX, 317L Self-welded welders are heat treated and pickled to obtain the best corrosion resistance. ASTM A-380 “Recommended procedure for descaling and cleaning of steel surfaces” can provide more information on pickling information. Table 6 ASTM A-240 provides the minimum mechanical properties Performance 317L 317LXTM 317LXNTM Tensile Strength MPa 515 515 550 Yield Strength （0.2%）MPa 205 205 240 Elongation (5%) 40 40 40 Hardness (Max) 217BHN / / UNS NO. S31703 S31725 S31726 Table 7 317LXN, 317LX, 317L stainless steel physical properties Density 8.0 g/cm3 Elastic Modulus 200 GPa Melting point 1320—1400 ℃ Thermal conductivity 20~100℃ 14.6 Walts/m °K Thermal expansion coefficient 100℃ 500℃ 1000℃ 16.5 18.2 19.5 10-5/℃ 10-5/℃ 10-5/℃ Specific heat 0.46 J/G °K Conductivity 0.79 μ-ohm-m Source: China Stainless Steel Pipe Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

The 304 stainless steel pipe is the most widely used for stainless steel, the equipment for food, general chemical equipment, and the atomic energy industry. 304 stainless steel pipe is a kind of common stainless steel pipe, it is widely used to make for a good comprehensive performance, corrosion resistance and formability of equipment and parts. The 304 stainless steel pipe is the most widely used stainless steel, heat resistant steel. Used in food production equipment, chemical equipment, nuclear power, etc. 304 stainless steel pipe chemical composition specification C Si Mn P S Cr Ni (nickel) Mo SUS304 less than or less than 0.08 is less than or equal to 1.00 or less than 0.03, or less than 0.05, or 0.03, 18.00-20.00, 8.25 ~ 10.50 Stainless steel is a versatile stainless steel material that is stronger than stainless steel in the 200 series. It is also good for high temperature, which can be up to 1000-1200 degrees. 304 stainless steel has excellent corrosion resistance and good corrosion resistance. The 304 stainless steel material concentration is less than 65 percent of the boiling temperature, which is highly resistant to corrosion. Alkaline solution and most organic acids and inorganic acids also have good corrosion resistance. In air or chemical corrosion resistant to corrosion medium of a kind of high alloy steel, stainless steel is a beautiful surface and corrosion resistant performance is good, need not after surface treatment, such as color of plating and the surface of the stainless steel inherent performance, used in a variety of steel a, often called stainless steel. It represents the performance of 13 chrome steel, 18-8 chrome nickel steel. From the perspective of metallography analysis, because the stainless steel containing chromium and make the surface form very thin chromium film, the film is isolated from intrusion in the steel corrosion of oxygen. Stainless steel pipe weight formula: [outer diameter – wall thickness] * 0.02491 = kg/meter (weight per meter) Source: China Stainless Steel Pipe Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

The quality of the surface of the stainless steel tube is mainly determined by the pickling process after the heat treatment. However, if the surface heat treatment is formed on the surface of the heat treatment, the surface roughness and uniformity can not be improved by acid pickling. So should pay full attention to heat treatment before heating or heat treatment surface cleaning. … The quality of the surface of the stainless steel tube is mainly determined by the pickling process after the heat treatment. However, if the surface heat treatment is formed on the surface of the heat treatment, the surface roughness and uniformity can not be improved by acid pickling. So should pay full attention to heat treatment before heating or heat treatment surface cleaning. If the thickness of the surface of the stainless steel tube plate is not uniform, the thickness of the surface of the base metal below the thick and thin place is also different, and the surface oxide of the surface oxide is dissolved and oxidized by the oxidized skin The degree of different, so the steel surface is not uniform. Therefore, when the heat treatment is heated, it is necessary to uniformly form the scale. To meet this requirement, attention should be paid to the following conditions. (1) If the surface of the workpiece is attached with oil, the thickness of the scale of the oil adhering site and the thickness and composition of the other parts are different and carburizing. The carburized part of the base metal will be severely attacked by acid. Heavy oil burner when the initial combustion of oil droplets, if attached to the workpiece, the impact is also great. The operation of the fingerprints attached to the workpiece will also be affected. Therefore, the bath for the major members do not touch the stainless steel pipe directly, do not make the workpiece stained with new oil. Must wear clean gloves. If the surface of the workpiece if the cold processing of lubricating oil, etc., must be in the trichlorethylene degreasing agent, caustic soda solution in the full degreasing and then rinse with warm water, and then heat treatment. (2) If the surface of the workpiece there are debris, to be other organic or gray attached to the workpiece, the heating of course, will have an impact on the scale. (3) Oxygen or oil flames Direct contact with the surface of the stainless steel pipe and the place where there is no difference in the scale of the scale. Therefore, it is necessary to make the treatment member not directly in contact with the flame port during heating. (4) If the local part of the treatment part before the heat treatment of residual scale, after heating the remaining parts of the scale and the site of no scale, there will be the thickness of the scale and composition of the difference, causing pickling after the surface is not Evenly, so not only pay attention to the final heat treatment, but also pay full attention to the middle heat treatment and pickling. (5) the effect of different surface finish If the surface finish is different, even if the same heating, the surface roughness and fine oxide scale is not the same. For example, where the local defects are cleaned and where they are not cleaned, the conditions of the formation of the scale are different, so that the surface of the workpiece is not uniform after pickling. (6) the difference between the furnace atmosphere Furnace atmosphere in the local differences, the formation of a scale will change, which is caused by acidity after the reasons for uneven. Therefore, in the heating, the furnace parts of the atmosphere must be the same. To this end, we must also consider the cycle of the atmosphere. In addition, it is necessary to evaporate the moisture, and the parts of the direct contact with the water vapor are different from those of the other parts, and the formation of the scale is, of course, It is different. Therefore, objects that are in direct contact with the heated workpiece must be fully dried to use. However, after drying, such as placed at room temperature, in the case of high humidity, the water will still condense on the surface of the workpiece. So, it is best to dry before use. Source: China Steel Tube Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

304 stainless steel pipe with its good heat resistance, and is widely used in the production of corrosion-resistant and forming the equipment and mechanical parts. At present, 304 stainless steel pipe has been widely used in food, chemical, atomic and other industrial equipment and decoration areas. GB 304 Chemical composition: grades 0Cr18Ni9, C≤0.08, Si≤1.00, Mn≤2.00, P≤0.035, S≤0.030, Ni: 8.00-11.00, Cr: 17.00-19.00 TP304 Chemical composition: C≤0.08, Si≤1.00, Mn≤2.00, P≤0.045, S≤0.030, Ni: 8.00-11.00, Cr: 18.00-20.00 304L Chemical composition: Grade 00Cr18Ni10, C≤0.03, Si≤1.00, Mn≤2.00, P≤0.035, S≤0.030, Ni: 8.00-11.00, Cr: 18.00-20.00, 304, TP304, 304L Simple distinction: ① 304 and TP304: 304 is the national standard, grade 0Cr18Ni9, TP is the abbreviation of Tube / Pipe, is the American standard representation, it is mainly used for piping with stainless steel; GB 304 and TP304, carbon content and Phosphorus content is different, the main difference is the difference between Cr chromium content, which TP304 chromium content is higher, reaching more than 18, so its corrosion resistance and price than the national standard 304 slightly higher. ② 304 and 304L comparison: 304L and 304 is the main difference between the different carbon content, of which 304 carbon content is less than or equal to 0.08, and 304L carbon content is less than or equal to 0.03; Secondly, 304 is a versatile stainless steel, It is widely used in the manufacture of equipment and components that require good overall performance (corrosion resistance and formability), and 304L is a variant of 304 stainless steel with a low carbon content for applications where welding is required. The lower carbon content minimizes the amount of carbides that are precipitated in the heat affected zone near the weld, and the precipitation of the carbide can cause the intergranular corrosion of the stainless steel in some environments. Domestic and foreign 304 grade table: Grade China Japan American British Germany 304 0Cr18Ni9 SUS304 TP304 304S15 X5Cr-Ni18 Source: China Stainless Steel Pipe Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

304 stainless steel pipe is 0Cr18Ni9 austenitic stainless steel pipe, is a very versatile 304 stainless steel tube, it is widely used in the production of good comprehensive performance (corrosion resistance and formability) of equipment and parts. The further study of 304 stainless steel is still a hot topic at home and abroad, of which the study and application of nickel are mostly manganese and nitrogen instead of nickel in stainless steel, and copper nickel is a new research direction. But at present, the research focus of domestic copper containing stainless steel is functional materials, focusing on the antibacterial properties of copper. However, there is very little research on improving the mechanical properties of copper. The creep deformation and fracture of copper containing stainless steel are studied abroad. The results show that copper is favorable for high temperature creep of stainless steel. The action of copper on 304 stainless steel tubes is similar to that of nickel, that is, it can increase the corrosion resistance of stainless steel. Therefore, it is theoretically feasible to add some copper to reduce the content of nickel in stainless steel. In addition to adding copper to nickel solution of nickel in the supply and demand contradiction to a certain extent, 304 stainless steel tube, make full use of associated copper and nickel ore, reducing the cost of removing copper purification, with considerable economic benefits. However, the addition of copper can reduce the room temperature strength and plasticity of Cr Ni austenitic stainless steel, which can improve the cold forming property of stainless steel, but decrease its strength. On the premise of ensuring the original strength of the stainless steel, the plasticity of the stainless steel is increased by adding copper. This requires a certain heat treatment of copper containing stainless steel before use, the choice of the parameters in the process of heat treatment, heat treatment, microstructure of copper containing 304 stainless steel mechanical properties and corrosion resistance, try to get both strong hardness and good ductility of the new stainless steel materials. 3% Cu was added to the 304 stainless steel tube. It is found that there is no precipitate copper phase in stainless steel, and copper exists in the form of solid solution. With the increase of annealing temperature, the strength and hardness of stainless steel decrease gradually. Annealing at 800 * 3H is the best annealing process, and moderate hardness can be obtained. With the solid solution time shortened, the strength and hardness of stainless steel increased, and the plasticity of copper containing 304 stainless steel plate increased. The solid solution aging scheme of 1080 * 3min+800 * 2H * can obtain better comprehensive performance. After the solution treatment, the copper containing stainless steel has homogeneous microstructure and higher austenite content, showing better comprehensive properties and excellent corrosion resistance. Source: China Steel Pipe Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)