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יוני 2018  (3)
מאי 2018  (24)
Application of stainless steel pipes
04/06/2018 04:04
susanchen
Application of stainless steel pipes in developed countries(1)

1. Japan's tap water supply pipe enters standardized orbit
Before 1955, galvanized pipes were commonly used in tap water supply pipes in Tokyo, Japan. From 1955 to 1980, a large number of plastic pipes and  420 stainless steel sheet composite pipes were used. Although the water quality and leakage problems of the galvanized pipes were partially solved, the leakage of the water supply pipe network in Tokyo was still very serious. The leakage rate had reached an unacceptably high 40% to 45% in the 1970s, and the “water hazard” was Problems have also gradually reflected that plastic pipes and steel-plastic composite pipes cannot meet the basic requirements for environmental protection.
The Tokyo Water Supply Bureau conducted a large number of experimental studies on the leakage problem for more than 10 years. According to the analysis, 60.2% of the leakage was caused by insufficient strength of the water pipe material due to the external force, and 24.5% of the leakage was caused by the unreasonable design of the pipe joint. 8.0 The leakage of % is caused by the unreasonable design of the pipeline circuit due to the high expansion rate of plastics. To this end, the Japan Waterway Association recommends improving the water pipe materials and connection methods. From May 1980, from the water supply auxiliary main line to the water meter, all the water supply pipes with a diameter of 50 mm or less use stainless steel pipes, pipe joints, elbows, and taps. As a result, the problem of water leakage is fundamentally solved. In 1982, Japan also developed stainless steel bellows. The users of the pipes can easily bend at any angle, greatly reducing the number of joints or even eliminating joints completely, saving installation time and costs.
In 1980, Japan established industrial standards (JIS G 3448 - Stainless Steel Pipes for General Plumbing). In 1982, the Japan Water Works Association developed "JWWA G 115 - Stainless Steel Pipes for Tap Water" and "JWWA G 116 - Stainless Steel Pipe Fittings for Tap Water". The standard, which was later developed as a standard for stainless steel corrugated pipes, was adopted by the Tokyo Water Supply Bureau as a standard material for 316 stainless steel bellows in 1999, which indicates that stainless steel is used as a pipe for tap water and a water supply pipe in a building to enter a standardized track. With the increase in the rate of stainless steel from 11% in 1982 to over 90% in 2000, the amount of water leakage has dropped from 50,000 in the end of the 1970s to 2-3 in 2000 (caused by stray currents). Leakage at joints) The use of stainless steel water pipes has greatly reduced the water leakage rate.
In the 1980s, especially after the 0-157 pathogenic coliform poisoning in 1996, people paid more attention to water quality. Stainless steel pipes and water storage equipment that can obtain good water quality were widely welcomed and widely used. In addition, Japan is an earthquake-prone region. In the Great Hanshin Earthquake of 1995, stainless steel tanks and pipelines were not damaged by earthquakes due to their high strength and excellent impact resistance, but they also assumed the task of supplying drinking water to people in the ruins. As a result, the outstanding seismic resistance of  440c stainless steel sheet tanks and pipes has attracted attention.
Today, in Tokyo, Japan, the penetration rate of stainless steel water supply pipes has reached almost 100%. All residential areas have installed stainless steel pipes, greatly improving water quality and enhancing earthquake resistance. Moreover, a large number of dual-use water transmission bridges (both for water pipelines and flyovers) are also widely used in 304 or 316 stainless steel and nearly 3,000 stainless steel water transmission bridges have been constructed since 1983.
Japan has been using stainless steel pipes for 40 years. Stainless steel pipes are now recognized by the Japanese as "the best drinking water container material."
0 תגובות
Application of stainless steel pipes
04/06/2018 04:03
susanchen
Application of stainless steel pipes in developed countries(1)

1. Japan's tap water supply pipe enters standardized orbit
Before 1955, galvanized pipes were commonly used in tap water supply pipes in Tokyo, Japan. From 1955 to 1980, a large number of plastic pipes and  420 stainless steel sheet composite pipes were used. Although the water quality and leakage problems of the galvanized pipes were partially solved, the leakage of the water supply pipe network in Tokyo was still very serious. The leakage rate had reached an unacceptably high 40% to 45% in the 1970s, and the “water hazard” was Problems have also gradually reflected that plastic pipes and steel-plastic composite pipes cannot meet the basic requirements for environmental protection.
The Tokyo Water Supply Bureau conducted a large number of experimental studies on the leakage problem for more than 10 years. According to the analysis, 60.2% of the leakage was caused by insufficient strength of the water pipe material due to the external force, and 24.5% of the leakage was caused by the unreasonable design of the pipe joint. 8.0 The leakage of % is caused by the unreasonable design of the pipeline circuit due to the high expansion rate of plastics. To this end, the Japan Waterway Association recommends improving the water pipe materials and connection methods. From May 1980, from the water supply auxiliary main line to the water meter, all the water supply pipes with a diameter of 50 mm or less use stainless steel pipes, pipe joints, elbows, and taps. As a result, the problem of water leakage is fundamentally solved. In 1982, Japan also developed stainless steel bellows. The users of the pipes can easily bend at any angle, greatly reducing the number of joints or even eliminating joints completely, saving installation time and costs.
In 1980, Japan established industrial standards (JIS G 3448 - Stainless Steel Pipes for General Plumbing). In 1982, the Japan Water Works Association developed "JWWA G 115 - Stainless Steel Pipes for Tap Water" and "JWWA G 116 - Stainless Steel Pipe Fittings for Tap Water". The standard, which was later developed as a standard for stainless steel corrugated pipes, was adopted by the Tokyo Water Supply Bureau as a standard material for 316 stainless steel bellows in 1999, which indicates that stainless steel is used as a pipe for tap water and a water supply pipe in a building to enter a standardized track. With the increase in the rate of stainless steel from 11% in 1982 to over 90% in 2000, the amount of water leakage has dropped from 50,000 in the end of the 1970s to 2-3 in 2000 (caused by stray currents). Leakage at joints) The use of stainless steel water pipes has greatly reduced the water leakage rate.
In the 1980s, especially after the 0-157 pathogenic coliform poisoning in 1996, people paid more attention to water quality. Stainless steel pipes and water storage equipment that can obtain good water quality were widely welcomed and widely used. In addition, Japan is an earthquake-prone region. In the Great Hanshin Earthquake of 1995, stainless steel tanks and pipelines were not damaged by earthquakes due to their high strength and excellent impact resistance, but they also assumed the task of supplying drinking water to people in the ruins. As a result, the outstanding seismic resistance of  440c stainless steel sheet tanks and pipes has attracted attention.
Today, in Tokyo, Japan, the penetration rate of stainless steel water supply pipes has reached almost 100%. All residential areas have installed stainless steel pipes, greatly improving water quality and enhancing earthquake resistance. Moreover, a large number of dual-use water transmission bridges (both for water pipelines and flyovers) are also widely used in 304 or 316 stainless steel and nearly 3,000 stainless steel water transmission bridges have been constructed since 1983.
Japan has been using stainless steel pipes for 40 years. Stainless steel pipes are now recognized by the Japanese as "the best drinking water container material."
0 תגובות
Inventory of materials used on high-speed ra
01/06/2018 03:49
susanchen


Inventory of materials used on high-speed rail(2


Ballastless track
Ballastless track is the trend and direction of the current and future development of railway construction in the world. The sleeper of ballastless track is made of concrete and water, and the roadbed does not need to be broken. It can reduce maintenance, reduce dust, beautify the environment, rails, and sleepers. On the concrete road, there are a lot of connections between the concrete pillows and the rails. The speed of the train can reach more than 200km/h?
The joints between the high-iron rail cement pillows and the rails and the foundation are all filled with polyurethane elastomers to seal them, one to make the connection stable, and not to be displaced due to climate change; the other is to prevent earthquakes and eliminate noise and increase passenger travel comfortability?
Polyurethane sleepers
In order to meet the requirements of high-speed train speed-up, the development of polyurethane sleepers to replace or partially replace concrete sleepers will certainly be the future development trend. In Western Europe, this technology has more mature research and application experience; in Japan, polyurethane sleepers have been in high-speed trains Applied on Shinkansen rails Compared to other materials, polyurethane sleepers have excellent durability and can reduce cycle costs?
Polyurethane adhesive
The demand for the production of high-speed trains for polyurethane adhesives has also increased significantly. Polyurethanes are responsible for glass bonding on vehicles, floor bonding, caulking, sealing, waterproofing, and other essential functions. According to EMU CRH3, Based on the basic, single car with polyurethane plastic about 84? 07L, converted to about 109? 3kg? Mainly used in adhesive bonding of window glass and sealing part of the filling?
Polyurea elastomer coating
As the high-speed rail adopts ballastless track, it is required that the protective layer not only has basic properties such as waterproof, anti-seepage and anti-cracking, but also can withstand the high speed, heavy load, alternating impact, etc. caused by the high-speed driving of the train. The polyurea coating is not connected. Seam, strong adhesion, truly waterproof overall, but also has excellent wear resistance, impact resistance, crack resistance, resistance to ultraviolet light and high and low temperature resistance, can meet the special requirements of high-speed rail?
Pantograph
At present, the conductors used in high-speed railways mainly include copper and silver (0.15% to 0.18% Ag), copper and cadmium (0.7% to 1.3% of Cd) or copper-tin alloy (0.3% Sn), etc. The development of high-tension and light weight new composite wire (ie, the appearance of copper, steel core) is the development trend?
The pantograph slide is an important collector element for the locomotive power supply system. Usually carbon slides, metal slides, metal carbon slides and powder metallurgy skateboards are used. Carbon slides are used in various countries, such as German ICE and French TGV? The self-lubrication of the material, as well as the high strength and impact resistance characteristics of the metal material, have become the most ideal skateboard material. In recent years, people have stepped into the stage of industrialization. Foreign countries are currently strengthening the carbon fiber metal matrix composite skateboard. Research, the material in the collection of electricity, self-lubricating, anti-impact performance and will exceed the existing skateboard?
At present, the immersion stainless steel slides researched at home and abroad have entered the stage of practical application. It mainly utilizes the porous nature of carbon slide materials, immersing high-conductivity metals such as molten copper or copper alloys under high temperature and high pressure. Carbon slide substrate to go, so that it has both carbon materials, self-lubricating and anti-arcing performance, but also with the collection of metal materials, high strength, high impact strength of the Hang bombs, become the best skateboard material?
At the same time, the study of carbon fiber-metal composite skateboards should be strengthened. Such skateboards will surpass the existing metal skateboards in terms of current collection, lubrication, and impact performance. Carbon skateboards, impregnated metal carbon skateboards and powder metallurgy skateboards, The application prospect is very broad?
Brake friction system
Brake friction system requires friction material with high and stable friction coefficient, better heat dissipation and wear resistance, high enough impact strength and shear strength, no abnormal wear and other damage to the wear parts. Less brake sparks, cheaper prices, and lighter weight?
Brake discs used alloyed cast iron for a long time in the past, but high-speed trains require the use of high-strength alloy steel forgings that resist hot cracking, such as Ni-Cr-Mo or Cr-Mo-V alloy steels, as well as metal matrix composites and CC composites. Driven disk? The heat-resistant cracked brake disk developed in Japan in 1997 can have a lifetime of more than 20 years; the carbon fiber composite disk in Germany is of good quality at a high speed of 250 km/h and has passed a 400 km/h bench test. ?
Currently used friction materials can be divided into phosphorus-containing cast iron? Powder metallurgy materials and synthetic materials? France TGV-A? Japan Shinkansen and other high-speed trains have adopted powder metallurgy brake lamellas, and generally copper-based materials? For iron-based? Aluminum-based materials, Japan, Europe, and the United States have recently added new products to develop new materials, such as ceramic granules or short fibers, to produce composite materials. In synthetic friction materials, German ICE trains have installed aluminum alloy discs/composite brake discs. The successful development and application of fiber-reinforced composite materials in friction-resistance braking materials has attracted attention and has become a research hotspot. For example, in 1997, the development of the brake pad was based on phenolic resin and graphite. Rubber and carbon fiber composite?
Vibration reduction and noise reduction materials
High-speed impact, vibration and noise increase, using vibration-reducing and noise-reducing components, such as Bo-elastic energy, fatigue resistance, and aging-resistant performance, to ensure safety and comfort.
Rubber components have been widely used in high-speed trains for anti-vibration, cushioning, sound insulation, sealing, insulation, elastic couplings, and air rubber springs, especially for noise reduction and noise reduction, and they have no comfort and stability for high-speed trains. Can replace the role?
The most noticeable application of rubber components is the six-joint rubber joint on the bogie. In the early 1950s, rubber materials were used abroad as rail cushions; in the 1970s, as the train speed increased, they were used in track structures. Natural rubber, neoprene, urethane rubber, and other elastomers are used as cushions for rails, pads, and cushions. In the 1980s, low-foaming polyurethane elastic materials have been widely used in rail 304 stainless steel. Japan has over 100 types of elastic materials. According to the screening, low-foaming polyurethane materials produced by reaction injection molding are most suitable for high-speed track materials.
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The key technology of smelting stainless steel
31/05/2018 03:51
susanchen
The key technology of smelting stainless steel in converter converter.


Iron water dephosphorization technology. In the process of smelting  420 stainless steel sheet with molten iron, it is the first to dephosphorize the iron water, or to blow off the phosphorus with the mixed iron car, or to remove the phosphorus in the re-blown converter.


Converter heat compensation technology. Because stainless steel is high alloy steel, it is necessary to add a large amount of cold material alloy during smelting. For example, it is not enough to make steel in the converter with the obvious heat and oxidation heat of molten iron. According to the calculation of converter in the molten iron conditions of smelting stainless steel SCTS304, SC1S316, SC1S410, SC1S420 as its heat inadequate when SUS430, were about 11.5%, 11.5%, 6.1%, 8.0% and 5.4%, low development cost for this thermal compensation technology is indispensable to the combined-blowing converter smelting stainless steel. The secondary combustion (known as PC gun) thermal compensation technology is commonly used in the top of the furnace.


The thermal compensation technology of the top of the furnace with crushed coke (granule) : the thermal compensation technology using the broken coke grain as the heat source is better than that of FeSi.

A. The remaining fragments of coke in the steel works are available in a wide range of sources and are cheap;

B. Even if used in large quantities, the amount of slag increases a lot;

C. The generated CO gas can be used as a heat source.
Through the secondary combustion thermal compensation: the shuangliu oxygen gun secondary combustion thermal compensation technique, can dig up the potential of chemical heat in the furnace, thus reducing the amount of coke thermal compensation, thus shortening the time of blowing and oxygen consumption.

The secondary combustion rate of CO can be improved by double - flow oxygen lance.

The secondary combustion rate was improved by controlling the ratio of oxygen to oxygen. In general, the ratio of oxygen to oxygen in the main hole is 20% and the secondary combustion rate is the highest. In addition, raising the height of the oxygen gun can also improve the secondary combustion rate.
Because of the stainless steel main alloy elements - Ming is easy to oxidation at high temperature, therefore in the converter smelting  440c stainless steel sheet not only should have enough decarburization ability, but also inhibit the oxidation of chromium elements.

According to the principle of metallurgy, the higher the temperature of molten steel, the more favorable to the process of decarbonization; The lower the partial pressure of CO in the converter is beneficial to the reduction of chromium, which can inhibit the oxidation loss of chromium while blowing oxygen decarburization. In order to meet the requirements of the theory of thermodynamics, the converter is usually used in dilution refining method is for a large flow of bottom blowing inert gas to dilute the converter internal decarburization reaction of CO concentration, reduce the partial pressure of CO. At the same time, it can also promote the stirring of molten steel and accelerate the decarbonization reaction. In addition, in terms of molten steel temperature control, must first overcome the problem of insufficient heat source, and then to be effective at high temperature (1700 ℃) or higher.
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2507 Super Duplex Stainless Steel Structure, P
30/05/2018 04:19
susanchen
2507 Super Duplex Stainless Steel Structure, Properties and Welding Process



Duplex stainless steel has become an important engineering material and is widely used in petrochemical, offshore and coastal facilities, oilfield equipment, papermaking, and shipbuilding environmental protection. 2507 duplex 303 stainless steel sheet is developed on the basis of second-generation duplex stainless steel 2205. There are currently grades such as SAF2507, UR52N+, Zeron100, S32750, and 00Cr25Ni7Mo4N. The 2507 structure consists of austenite and ferrite, and austenite. The dual characteristics of stainless steel and ferritic stainless steel, it has lower thermal expansion coefficient and higher thermal conductivity than austenitic stainless steel. Its PREN is greater than 40, and it has high resistance to pitting corrosion and clearance. Corrosion, resistance to chloride stress corrosion cracking, while having high strength, high fatigue strength, low temperature and high toughness, etc., is a widely used duplex stainless steel. In recent years, with the continuous expansion of the application of duplex stainless steel, the increasing demand for welding technology has accelerated the development of welding technology. Therefore, summarizing and exploring the research results of 2507 stainless steel weldability at home and abroad have important engineering practical significance for the application of 2507 duplex stainless steel.
The very low C content in chemical composition of 2507 duplex stainless steel can improve the weldability of the steel and reduce the tendency of carbides to precipitate in the grain boundary during heat treatment, increase intergranular corrosion resistance, high chromium, high molybdenum and higher nitrogen content, Can improve the corrosion resistance, make it have a good resistance to formic acid, acetic acid, nitrides and other uniform corrosion, pit erosion resistance, stress corrosion resistance. Nitrogen is added to the stainless steel as an alloying element to increase the stability of austenite and balance the proportion of the phase in the dual phase steel. The strength of the steel is increased without affecting the plasticity and toughness of the steel, and Ni can be partially replaced by the stainless steel. The cost, N, has the effect of delaying the dispersion of intermetallic compounds and stabilizing austenite in duplex stainless steels.
The 2507 duplex stainless steel is composed of ferrite and austenite. The austenite is distributed on the ferrite matrix in strips. The interface between the austenite and the ferrite is not smooth at high magnification. It is serrated. It shows that during cooling after rolling, austenite formation is nucleation and growth at the ferrite interface. The presence of austenite in the duplex 309 stainless steel sheet structure can reduce the tendency of high-chromium ferrite brittleness and grain growth, improve the weldability and toughness, and the chromium-rich ferrite can increase the yield strength of austenite in stainless steel. Resistance to intergranular corrosion and stress corrosion, ie, ferritic duplex structure with high strength, high toughness, while maintaining high stress cracking resistance, pitting resistance, crevice corrosion resistance, especially chloride, sulfide The material has high resistance to stress corrosion cracking, and therefore, can effectively solve the problem of long-term failure of austenitic stainless steel due to local corrosion.
The 2507 duplex stainless steel welding method has a wide applicability and can be welded in a variety of ways. The heat input and cooling rate of the weld affect the phase balance of the ferrite and austenite and the properties of the welded joints, in order to ensure proper weld organization. In comparison with good mechanical properties and corrosion performance, excessive or small heat input should be avoided during welding. The control should be 5-20 kJ/cm. The lower limit should be taken when welding thin-walled parts, and the heat should be appropriately increased when welding thick-walled parts. Input, inter-channel temperature should not exceed 100 °C.

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Improvement and Optimization of Ultra-low Carb
29/05/2018 03:57
susanchen
Improvement and Optimization of Ultra-low Carbon Martensitic Stainless Steel Smelting Process

Ultra-low carbon martensitic 303 stainless steel sheet (06Cr13Ni46Mo and 06Cr16Ni46Mo) are important materials commonly used for crowns, rings, vanes and guide vanes in important parts of hydraulic turbines. This series of stainless steel materials is difficult in smelting technology, and the quality requirements of the products are relatively high. Especially in the manufacture of Three Gorges hydropower generating units, the three major hydropower equipment manufacturing companies in China have formulated domestic and foreign hydropower manufacturing technologies and standards. The Three Gorges Standard of the key components of hydropower equipment (the requirements of the materials involved in the standard represent the highest level in the industry in China), and the requirements for molten steel composition are: ω(C) ≤ 0.05%, ω(P) ≤ 0.028%, ω(S) ≤ 0.015%, ω (Si) ≤ 1.00%, ω (Mn) ≤ 1.00%, ω (Cr) ≥ 12.45%, ω (Ni) = 3.5 to 4.5%, ω (Mo) = 0.40 to 1.00%, ω ( O) ≤ 80 × 10-6, ω (N) ≤ 150 × 10-6, ω (H) ≤ 3 × 10-6.
Domestic and foreign manufacturers to produce high-quality stainless steel castings, the main use of electric arc furnace + refining (AOD, VOD, LF, etc.) for the production, which uses AOD smelting stainless steel, stainless steel refining has become the dominant technology. At present, domestic and foreign manufacturers in the production of this series of stainless steel materials, in the production and follow-up process is more likely to produce cracks, in the course of the use of cracks. Therefore, in order to improve the quality of the series of material castings, it is necessary to improve the overall performance of the casting by increasing the internal quality of the smelting molten steel.
The technical personnel of the Dongfang Electric Group pointed out that the existing process of 309 stainless steel sheet smelting of the company had problems such as long decarburization time, large oxygen consumption, high bath temperature, and long residence time at high temperature. Through the process improvement and the use of AOD refining furnace, the quality of molten steel was improved. .
As we all know, the key to oxygen decarburization is to control the reaction of oxygen in molten steel with carbon, chromium, silicon, manganese and other elements. Based on the principle of steel metallurgy and combined with the use of AOD, the technicians improved and optimized the main process parameters of the original stainless steel smelting.
The AOD method uses argon and oxygen gas to blow molten steel, and blows in the form of a mixed gas from the side of the furnace bottom to the molten pool. In the blowing process, since the CO partial pressure is reduced by diluting with argon, it is greatly advantageous for the decarburization and chromium preservation at the time of smelting stainless steel. In the reduction stage of AOD refining, due to the deoxidation of ferrosilicon and limestone slag, and the strong stirring of argon, the molten steel can be deeply desulfurized; the intense stirring of argon during the AOD refining period can promote the separation of oxides in the molten steel. As it floats, the cleanliness of the molten steel increases, so the content of inclusions in the molten steel is small, and there is almost no large particle inclusions. The main form of inclusions is also changed from the manganese silicate in the electric furnace method to calcium silicate.
In addition, AOD can also remove lead from steel during the blowing process. Studies have shown that stainless steel contains a certain amount of lead will affect its thermal processing performance, and after AOD blowing, the finished steel ω (Pb) ≤ 10 × 10-6 or less, will not affect the performance of steel.
Through process improvement and the use of AOD, high-quality molten steel was obtained, and deoxidation was performed using Si-Ca, Si-Fe, etc. The molten steel ω(O) was reduced to 80×10-6; active lime was used to enhance desulfurization and make ω(S) ) to 0.015% or less, greatly improved the cleanliness of molten steel to meet the requirements of smelting composition and various physical and chemical indicators; the content of harmful gas components and spherical oxide inclusions in steel (spherical oxide rating does not exceed 2.0) is greatly reduced The improvement of molten steel purity enhances the ability of the casting matrix to resist cracks.
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Ferrite Stainless Steel [N] Control Technology
28/05/2018 03:59
susanchen
It can be divided into five types: ferrite, martensite, austenite, duplex (ferrite + austenite) and precipitation hardening. Ferritic  15-5 PH Stainless Steel Bar are widely used in the kitchen, household appliances, decoration, and automotive fields because of their good processability; martensitic stainless steels are hardened by heat treatment and are mainly used in tool steels and surgical instruments, blades, and tableware; these two types Stainless steel requires that the [N] content be controlled as low as possible. At present, the high-purity steel ω[N] is less than 100×10-6. Low nitrogen control technology is a key technology for the manufacture of ferrite and martensite.
Austenitic grades are very high, because the presence of nickel will cause significant changes in the structure and properties of stainless steel, corrosion resistance is improved, and pitting corrosion resistance is added after the addition of molybdenum. It is the largest part of the stainless steel family and can be used in many different ways. Uses, from the washing to the chemical environment of the corrosive environment, human implants and so on. Duplex stainless steel has two-phase structure (ferrite + austenite) and the strength of steel is about twice that of austenitic stainless steel. Therefore, dual-phase steel exhibits good comprehensive corrosion resistance and has a very low stress corrosion cracking tendency. , It is widely used in the maritime field, such as desalination, industrial storage and other industrial equipment. Both types of stainless steel require control of nitrogen alloying.
Today, the world's stainless steel production consumes 30-40% of ferritic stainless steel and 49-59% of austenitic stainless steel; it requires ferrite stainless steel to have a lower [N] content in austenitic stainless steel. N] The content is getting higher and higher, so [N] control technology is a problem facing stainless steel manufacturing.
Control technology of ferritic stainless steel [N]: Ferrite stainless steel has a low price and has a wide market demand. Therefore, how to reduce the content of [N] becomes a professional core technology of a stainless steel manufacturing plant. At present, in non-vacuum smelting technology plants, the core technology is to reduce the N2→2[N] reaction, that is, to reduce the increase in the core technology; and the vacuum smelting technology is to promote the reaction of molten steel 2[N]→N2. Promote the core technology of [N].
Control technology for austenitic stainless steel [N]: The control of austenitic stainless steel [N] first requires the selection of the best process flow. Under normal pressure conditions, non-nitrogen-controlled, nitrogen-controlled, and nitrogen-neutral stainless steels have achieved industrial production, and high-nitrogen-type control technologies have only one application at home. Second, we must grasp the control technology or process parameters of each link [N], because [N] the solid solution speed, the amount of solid solution and molten steel temperature, time, molten steel mixing strength, steel stirring medium and so on.
Through the analysis of various nitrogen control process characteristics and control processes of stainless steel, the following conclusions can be drawn:
(1) Non-vacuum conditions The main technique for producing ultra-low [N] ferritic stainless steels is to reduce the dissociation of N2 during arc melting, reduce the intense mixing of refining, and reduce the N2 contact time between molten steel and air.
(2) The main technique for producing ultra-low [N] ferritic stainless steel under vacuum conditions is to control the [N] addition of the alloy during the addition process, and to reduce the [N] content again when the [C] is removed under vacuum.
(3) The nitrogen (N)-type and medium-nitrogen type austenitic stainless steels under the condition of normal pressure increase [N] technology is mainly to control the N2 flow rate and blowing time during refining. The high-nitrogen stainless steel not only uses N2 for alloying, but also adds another refining means, that is, partial nitrogen alloying of the LF furnace [N].
(4) The development of high nitrogen austenitic  13-8 Stainless Steel Bar control [N] technology has filled the domestic gap. High-nitrogen austenitic stainless steel is a typical steel representative for saving resources and sustainable development.
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Inventory of materials used on high-speed rail
25/05/2018 03:59
susanchen
Inventory of materials used on high-speed rail(1)


The significance of China's high-speed rail exports is not only the “sea-going” of individual industries, but the “going out” of the entire industrial chain. Although the current market size is small, once it is recognized by overseas markets, it will reshape the global brand image made in China. , driving the development of the upstream and downstream sub-sectors of the industry chain? Today, Xiao Bian took everyone to look at the high-speed rail materials?
For high-speed railways, higher requirements are placed on the strength, fatigue performance, light weight, and processability of new materials. The application of new materials is mainly based on the following aspects:
Railway vehicle
Stainless steel is mainly made of nickel-chromium austenitic stainless steel. Because of its high corrosion resistance and aesthetic characteristics, it is used in Japan, the United States, and the former Soviet Union. Under the premise of ensuring strength and rigidity, the thickness of the skeletons such as beams and pillars is limited by 3.2 to 6.0 mm of ordinary steel is reduced to 1.0 to 1.5 mm, which can reduce weight by about 40%. In the early 1960s, Japan took the lead in developing stainless steel vehicles. Its light weight, energy saving, and no need for painting resulted in a significant economy. Benefits: More than 5,000 stainless steel vehicles currently account for more than 10% of all buses?
The main application: stainless steel body because it is not easy to solve the problem of air tightness of the body, only for the production of 20km / h speed class car body and the car carrying and decorative parts.

Aluminum alloy
Aluminum has a low density of only 2.7 (a light metal), about 1/3 that of steel. Because the surface of aluminum is easily oxidized to form a dense and stable oxide film, the corrosion resistance is good. Aluminum has good castability. Aluminum has a low melting temperature, good fluidity, and is easy to manufacture parts with various complex shapes. The aluminum alloy still maintains the characteristics of light weight, but its mechanical performance is obviously improved.
main application:
The first is as a force component;
The second is as a door, window, tube, lid, shell and other materials;
The third is as a decoration and thermal insulation material? Aluminum alloy is easy to process and has a high degree of heat dissipation?
In particular, the engine part of the vehicle is particularly suitable for the use of aluminum alloy materials. Almost entirely here is a world of aluminum alloys. In addition, the processing technology of aluminum alloys is diverse and versatile.
In the long term, the price of aluminum alloy is moderate, while the higher price of aluminum makes the manufacturing cost of vehicles increase. However, due to aluminum alloys making vehicles lighter, the weight of vehicles brings about an increase in transport capacity, energy consumption, and maintenance. Reduced costs? According to statistics, for every 10% reduction in the weight of vehicles, fuel can be saved by 8%. Aluminum products can achieve 100% recycling when scrapped and recycled. Recycling aluminum can reduce energy consumption by 95%.
As early as the 1950s, some of the world’s more advanced countries began to use aluminum profiles to manufacture railway vehicles, including the United States, Canada, Japan, Russia, Germany, and France. At present, aluminum alloys have been widely used in domestic high-speed rail cars. Experts in the industry pointed out that aluminum alloy materials must be lightweight in high-speed trains with a speed of 300 km/h or more, aluminum rails should be used in all 350 km train cars except the chassis, and CRHI? CRH2 is currently used in China EMUs. CRH3?CRH5 four types, in addition to CRHI type body is stainless steel, the other three kinds of EMU body are aluminum alloy material?
In recent years, attempts have been made to manufacture car body skeletons from aerospace materials such as magnesium alloys and Chin alloys, which weigh only 66% of that of aluminum alloys.
Composite materials
Composite materials have been applied to vehicles, and their usage has been increasing, which represents the future development trend. Fiber-reinforced resin matrix composites (FRF) because of high specific strength (stiffness), fatigue resistance, corrosion resistance, heat insulation, and flame retardant can be designed. Such advantages as strong nature, the United Kingdom, Japan, and Germany began to be applied to non-structural parts in the 1960s, and they are now increasingly used in various structural parts such as the use of fiberglass reinforced plastics and aramid fiber-reinforced epoxy at the front ends of cars and front ends. Resins, etc. Currently, in western Europe, the composite materials used in the manufacture of railway vehicles are classified according to the types of fibers, and glass fibers account for 58%. Aramid fibers account for 20%, carbon fibers account for 20%, and others account for 2%. Types, polyester accounted for 35%, ethylene carbonate accounted for 22%, epoxy resin accounted for 21%, phenolic resin accounted for 15%, modified acrylic resin accounted for 4%, other 3%?

Bogie
The bogie frame is a particularly important high-strength component. It concerns the safety of the entire vehicle. The turret must meet the requirements of safety, operating comfort, wear-resistance and easy maintenance.
The use of high-quality carbon steel, low-alloy, low-carbon, high-strength steel, and weather-resistant steel manufacturing frameworks have recently been the focus of research on polymer composites and aluminum alloys.
Vehicle interior equipment
Vehicle interior equipment and equipment mainly include decorative plates, toilets, washrooms, seats and water tanks, etc., mainly aluminum alloy and polymer materials, such as decorative plates laminated with aluminum alloy on a layer of non-combustible fiber-reinforced plastic, toilets ? League washing room? Seats and tanks also take into account the health and corrosion resistance, but also non-combustible is better?
Wheel system
In addition to sufficient strength, toughness, and wear resistance, wheel and rail materials must also be resistant to scratches and peeling.
As far as the line is concerned, the main characteristics of high-speed railways that distinguish them from ordinary railways are large curvature radius, high strain rate, light axial weight, large traction, small wear on rails, and relatively prominent fatigue damage. Therefore, the selection requirements for rail materials are relatively high. high?
For rail materials, European railways have been conducting research on alloy rails. For example, non-heat-treated Cr-Mo alloy rails have the ability to withstand short-wave wear in addition to high cyclic softening resistance. They are the future rails. One of the key choices for materials? In addition, efforts should be made to strengthen and toughen the rail steel, and to develop the full-length heat-treated steel rails, rare earth steel rails and new rails for noise reduction and vibration reduction.
At present, 347 Stainless Steel Bar being studied abroad are better than pearlite steels in anti-peeling performance, but they are still in the experimental stage. In order to reduce weight, Germany is studying composite wheels, that is, wheel center adopts FRP, and then put on steel wheels and tires. ?
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Three major causes of oxidation in stainless
24/05/2018 04:09
susanchen
Three major causes of oxidation in stainless steel

Three major causes of oxidation often occur in  309 Stainless Steel Pipe:
1, the production process causes: This is one of the reasons leading to the production of steel products oxidation, from the production process and product characteristics, the formation of a thin oxide film on the surface of the product is to avoid the occurrence of oxidation of the basic process, but also steel products Different from other main characteristics of iron and steel products, but due to the lack of production process or negligence, the performance of the oxide film is incomplete and discontinuous. The oxygen in the air directly reacts with some elements of the product to undergo a redox reaction, resulting in The product showed oxidation.
2, the ratio of product ingredients Reasons: Some manufacturers in order to reduce production costs, thereby reducing the proportion of some important elements such as chromium, nickel, and increase other such as carbon content, this is not strictly in accordance with the product model, product characteristics The production of ingredients is not only to reduce the quality of the product, for example, when the content of chromium in the 304 stainless steel tube is insufficient, it not only affects the corrosion resistance and formability of the product, but also exists in the chemical industry, equipment and production industries. Potential product quality safety hazards; at the same time, it also affects the appearance and oxidation resistance of the product.
3. Man-made reasons: This is also one of the reasons for the oxidation of some of the products most frequently encountered by consumers when using stainless steel products. Some consumers improperly use the products in their use and maintenance, especially  310 Stainless Steel Pipe   products used in the food and chemical equipment industry. Occurrence of man-made oxidation is high. For the oxidation of man-made steel products, it is necessary to have the correct knowledge of product use and to carry out reasonable and effective maintenance and maintenance on a regular basis, thereby reducing the oxidation caused by improper use of man-made materials.

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Ten characteristics of stainless steel
23/05/2018 04:05
susanchen
Ten characteristics of stainless steel combination tank


304 Stainless Steel Pipe combination water tank, SUS304 stainless steel ball faceplate combined welding water tank is a new type of water tank utilizing new technology and new technology. The design of the stainless steel composite tank bearing plate is reasonable. It makes full use of the tensile characteristics of stainless steel metal materials and has the purpose of decompressing the pressure. The average force of all the plates is uniform, the appearance is elegant and there is no deformation, and the integrity is good. Compared with other types of tanks, the following Raised strengths:

First, stainless steel composite tank bearing design
The ball-panel water tank takes full advantage of mechanics and evacuates the pressure of the water, preventing large circular tanks from being inconvenient to process and occupying large defects. At the same time, the stainless steel combination tank also prevents the problem of unequal bearing capacity of the square tank, and utilizes the largest bearing on the circular arc surface to greatly increase the bearing capacity and the anti-seismic performance of the tank itself.

Second, the overall structural design of stainless steel combination tank
The inner lacing structure of the ball-panel water tank adopts a strictly designed mesh structure and is supplemented with diagonally-stretched ribs at specific angles, so that the various parts of the water tank are united together to form an integral body. When there is water in the water tank, the inner lacing It plays a supporting role to prevent the problem of easy deformation of the external reinforcement ribs.

Third, the stainless steel combination tank hygiene pollution-free
Imported high-quality SUS304-2B stainless steel plate, the polishing surface will not allow dirt to accumulate, which facilitates the cleaning of the water tank in the future. The opacity prevents the harmful algae such as Chlorella from breeding, which is suitable for modern people's high demand for drinking water and is suitable for advanced The property can be used as a publicity point for real estate developers to increase sales of properties.

Four, stainless steel combination tank life
SUS304 stainless steel water tank is suitable for storing water or physical properties similar to water medium. Medium temperature: 0~900C; ambient humidity: 0~98%. Because the material itself has a strong corrosion resistance, its service life is much longer than ordinary materials, but also due to the use of high-tech argon arc welding process, so that the entire welded structure prevents the assembly tank rubber strips from aging and causing leakage. The common problem of leakage does not need to be exchanged in the future, and the service life can reach 40 years.

Five, stainless steel combination tank is particularly suitable for making large-tonnage water tank
Large-tonnage tanks have large capacity and require high skill in inner lacing; pressure is high, and the requirements for tensile and shear resistance of the tank materials are also high. Stainless steel combination tanks in the form of ball plates and net-shaped lacing are used for tensile strength. Shear can meet the needs of large-capacity water tanks.

Six, stainless steel combination tank is simple and easy to assemble
The stainless steel ball-panel water tank adopts the thin-walled stainless steel plate, and at the same time, it also has the advantages of the assembled water tank. The use of a standard plate form to the site welding assembly does not affect the construction of the structure. The stainless steel combination water tank has the advantages of high assembly speed, strong integrity, light weight, and no additional load on the building.

Seven,  304L Stainless Steel Bar combination tank shape aesthetic
The stainless steel combination water tank adopts the film coating process in the mechanical processing, transportation, and assembly process, so that the scratches caused by friction are greatly reduced during the processing, and then the equipment is torn to the film after the equipment is assembled and the equipment is protected. , The product is bright and elegant.

Eight, stainless steel water tanks cheap
The design of the ball plate and the structure of the net-shaped inner reinforcement are combined with a stainless steel water tank, which can effectively reduce the wall thickness of the water tank. Thin-walled stainless steel plates are used, so that the cost is greatly reduced and the performance is better. The customers use the lower price High quality equipment.

Nine, stainless steel tank insulation structure is good
In order to match the curvature of the ball panel, a special polyurethane insulation board in line with the plate type is specially made. The glass fiber reinforced plastic cover is covered with a white enamel coating. Its appearance is elegant, and it is clean and generous, and the heat preservation function is much better than other materials. product.

Ten, stainless steel combination tank cleaning
Stainless steel composite water tank ball panel's own bright surface is not easy to attach dirt, stainless steel combination tank is easier to clean than other materials, in addition, the ball panel form in the lowest point of the bottom of the tank drain pipe, so that the sewage more easily discharged, will not form stagnant water, easy Cleaning management.

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