Five Small Knowledge of Stainless Steel

A, stainless steel plate weight calculation formula: length * width * thickness * = weight proportion

For example: 1.5 mm * 1000 mm * 1000 mm, 1 * 2 * 1.5 * 7.93 = 23.79 kg

Second, stainless steel pipe weight calculation formula: (diameter and wall thickness) * wall thickness * = m weight proportion

For example: 108 * 4 mm tube, (108-4) * 4 * 0.02491 = 10.36 kg

Third, what is the difference between 304 and 201 stainless steel tube:

1, the price is different: 304 quality is better, but the price is expensive, 201 less, but the price is cheap.

2, different components: 304 is 8 nickel chromium 18, 201 to 1 nickel chrome 13

3, different antirust performance: 304 rust resistance is strong, weak 201 rust resistance

4, the intensity is different: the yield point 205 mp of 304 steel tensile strength 515 mpa, or 201 steel yield strength 275 mpa, the tensile strength of 520 mpa or higher

Four, why will rust stainless steel:

1, many people think that stainless steel tube will not rust, this is a kind of wrong one-sided view. First of all, no rust and corrosion resistance of stainless steel tube is conditional. Stainless steel piping in weak corrosion environments, such as atmosphere, fresh water is not rust of steel tube, and must be 12% or higher chromium content in steel. If the chromium content is low or not weak corrosion environments, such as in the atmosphere (including weak corrosion in atmospheric environment, but have local rich collection of Cl - concentration) under the condition of use, will rust. Acid-resistant steel tube is in strong acid, alkali, salt and other corrosive medium corrosion of the steel tube, but corrosion only under certain conditions, such as medium type, temperature, concentration, content of impurities, such as flow rate, pressure must be. Not in any conditions in the world is not rust, corrosion resistance of stainless steel pipe.

2, stainless steel surface dust containing other metal elements deposit savings or heterogeneous metal makings of attachments, in the humid air, attachments and stainless steel, the condensed water between the both together as a micro battery, triggers the electrochemical reaction, protective film is damaged, to call the electrochemical corrosion.

3, stainless steel surface adhesion with organic fluids (such as melon seeds, sputum noodle soup, etc.), under the condition of water is oxygen, organic acid, organic acid is formed for a long time on the surface of metal corrosion.

4, stainless steel surface adhesion containing acid, alkali, salt substances (e.g., decorate the walls of caustic soda and lime water spray test) cause local corrosion.

5, where there is air pollution (contains large amounts of hydrogen sulfide and oxide, oxidation atmosphere), in the condensation water, formation of nitric acid, acetic acid, liquid, chemical corrosion.

If you would like to know more about stainless seamless steel pipe and carbon steel pipe,pls contact:hunan great steel pipe co.,ltd

What is Carbon Steel?

Carbon steel is steel in which the main interstitial alloying constituent is carbon in the range of 0.12–2.0%. The American Iron and Steel Institute (AISI) definition says:

Steel is considered to be carbon steel

 when no minimum content is specified or required for chromium, cobalt, molybdenum, nickel, niobium, titanium, tungsten, vanadium or zirconium, or any other element to be added to obtain a desired alloying effect;

 when the specified minimum for copper does not exceed 0.40 percent;

 or when the maximum content specified for any of the following elements does not exceed the percentages noted: manganese 1.65, silicon 0.60, copper 0.60.

The term "carbon steel" may also be used in reference to steel which is not stainless steel; in this use carbon steel may include alloy steels.

As the carbon percentage content rises, steel has the ability to become harder and stronger through heat treating; however, it becomes less ductile. Regardless of the heat treatment, a higher carbon content reduces weldability. In carbon steels, the higher carbon content lowers the melting point.

If you would like to know more about carbon steel pipe(include seamless steel pipe),pls viist:hunan great steel pipe co.,ltd

Seamless steel pipe of Hunan Great Steel Pipe Co.ltd

Hunan great steel pipe co.,ltd is backed by stong reseach& developmnt platform.Our production based spread over Tianjin,Jiangsu,Hunan and Jiangxi.A product development center has been set up in Tianjin,to control the development,production,quality control,and transportation to essure reliable product quality.

Our seamless steel pipe include:API 5CT Tubing,API 5CT Casing,API 5L Line Pipe,ASTM  A53,ASTM A106 and so on.

Carbon Steel Pipe

Carbon steel pipe mainly refers to the carbon mass fraction is less than 2.11% without containing deliberately added alloying elements of steel,with the level of carbon contained in a steel being one of the most important factors to be influence on its the strength of the steel,the hardness increase,and reduces ductility,toughness and weldability.

If you would like to know more about carbon steel pipe,pls contact:Hunan great steel pipe co.,ltd.

API 5L X42 Line Pipe

X42 line pipe steel grade for X42 line pipe, line pipe is to put out the ground of oil, gas, water, pipeline through the pipeline to oil and gas industry enterprise. Line pipe including seamless pipe and welded steel pipe, the pipe end with flat end, with threaded end and socket end; Its connection mode for welding, coupling connection, socket connection, etc.

Grade of steel including X42-70, varieties have a land line pipe and seabed pipeline. Line pipe production is currently using micro alloying heat treatment technology, the production cost of stainless steel seamless tube significantly higher than that of welded pipe, and with the improvement of steel grade, such as the above X80 grade pipeline steel tube limits on carbon equivalent, seamless steel tube of conventional technology is difficult to meet user requirements; Now every 12 cr1mov alloy pipe factory in for the improvement of line pipe corrosion resistance, the use of stable performance and low temperature, high temperature environment to carry out the scientific research work.

If you would like to know more about seamless steel pipe and carbon steel pipe ,pls contact us.

ASTM A106 Line Pipe

A106 line pipe is belong to the American standard of oil line pipe, line pipe is to put out the ground of oil, gas, water, pipeline through the pipeline to oil and gas industry enterprise. Line pipe including seamless pipe and welded steel pipe, the pipe end with flat end, with threaded end and socket end; Its connection way as the end of welding, coupling connection, socket connection, etc.

Heat treatment process of high grade pipeline tube with the development of the pipeline steel plate technology and the progress of welded pipe forming, welding technology, the application range of the pipe with welded pipe in gradually expanding, especially in the large diameter welded pipe class scope the advantage of more wet, and cost factors, welded pipe has been dominant in the field of line pipe, which limits the development of stainless steel seamless steel line pipe. About 2004 t 2004 seamless line pipe production, steel grade including X42-70, varieties have a land line pipe and seabed pipeline.

ASTM A106 seamless steel pipe is your good choice for liquid transport. Hunan great steel pipe co.,ltd is good supplier of carbon steel pipe.

Standard of ASTM A106-20006 (seamless steel pipe)

ASTM A106-2006标准

标  准
ASTM A106高温用无缝碳钢公称钢管
用途	适用于弯曲、卷边及类似的成形加工

标准	外径(mm)	+(mm)	-(mm)
ASTM A106	6-40	0.4	0.4
	40-100	0.8	0.8
	100-200	1.6	0.8
	200—450	2.4	0.8
	450-650	3.2	0.8
	650-850	4.0	0.8
	850-1200	4.8	0.8

ASTM A106壁厚、重量允许偏差及长度范围
壁厚	重量	长度范围
±12.5％	+10%  -3.5%	一般范围1	一般范围2
		4.8-6.7m+ 5% (3.7-4.8m).	最小平均10.7m+ 最小6.7m+ 5％(4.8-6.7m)两倍长度.

ASTM A106化学成分(%)
牌号Gr	C	Si	Mn	P	S	Cr	Mo	Cu	Ni	V
A	≤0.25	≥0.10	0.27-0.93	≤0.035	≤0.035	≤0.40	≤0.15	≤0.40	≤0.40	≤0.08
B	≤0.30	≥0.10	0.29-1.06	≤0.035	≤0.035	≤0.40	≤0.15	≤0.40	≤0.40	≤0.08
C	≤0.35	≥0.10	0.29-1.06	≤0.035	≤0.035	≤0.40	≤0.15	≤0.40	≤0.40	≤0.08

ASTM A106力学性能(MPa)
牌号	抗拉强度	屈服强度
GrA	≥330	≥205
GrB	≥415	≥240
GrC	≥485	≥275

Above is the detail of A106 seamless steel pipe standard, if you would like to know more about carbon steel pipe,pls contact:hunan great steel pipe co.,ltd

Difference useful of seamless steel pipe

1. Structure with seamless steel pipe (is used for general structure and the mechanical structure of seamless steel pipe
2. The fluid transport in seamless steel pipe is used for conveying water, oil, gas and other fluid generally seamless steel pipe
3. The high pressure boiler seamless tube is used in the manufacture of high pressure and over pressure of the water tube boiler heating surface quality carbon steel, alloy steel and stainless heat resistant steel seamless tube.
4. Oil cracking with seamless tube is suitable for oil refinery furnace pipe, seamless tube heat exchangers and pipe.
5. The geological drilling with steel tube is for the use of geological departments the core drilling pipe, can be divided into the drill pipe, drill collar, according to the use of core pipe, casing and precipitation, etc. 8. Diamond core drilling for seamless tube  is used for diamond core drill pipe, core rod, casing seamless tube.
6. Oil drill pipe (which is used in oil drilling internal upset or external upset on both ends of seamless pipe. Pipe points two car and car silk, silk work joint connection, no car work butt welding method and the tool joint connection.
7. The class I made of carbon steel seamless pipe is ship pressure piping, pressure piping Ⅱ, boiler and overheating for carbon steel seamless tube. Carbon steel seamless pipe wall temperature does not exceed 450 ℃, the alloy steel seamless tube wall temperature over 450 ℃.
When selecting a seamless tube must want to know what to use for the purpose of, because each seamless pipe price is different to best advantage.

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seamless steel pipe

General use seamless steel pipe is made of 10, 20, 30, 35 and 45 high quality carbon steel guitar 16 mn, 5 MNV low alloy structural steel or 40 cr, 30 crmnsi, 45 mn2 and 40 MNB guitar made from hot rolled or cold rolled steel. Made in 10, 20, such as low carbon steel seamless pipe is mainly used for fluid pipelines. 45, 40 cr made of medium carbon steel  pipe manufacturing machinery parts, such as the stress of the automobile and tractor parts. Seamless steel pipe used in general to ensure the strength and the flattening test. Hot-rolled steel pipe with hot rolled or heat treatment state delivery; Cold rolled as heat to heat treatment state delivery. Low medium pressure boiler seamless steel pipe: used in the manufacture of all kinds of low intermediate pressure boiler superheated steam pipe, water pipe, water wall tube 214534589 and locomotive boiler superheated steam pipe, great smoky, small pipe and tube arch brick, etc. With the high quality carbon structural steel hot rolled or cold rolled seamless steel tube (dial). Mainly use 10 and 20 # steel manufacturing, in addition to guarantee the chemical composition and mechanical properties to do water pressure test, edge, flaring, flattening test, etc. Hot rolled in hot rolled state delivery, cold rolling (dial) in heat treatment state delivery.

2FBE Coating Steel Pipe

2FBE Coating steel pipe widely used for Marine facilities, oil chemical industry, construction industry and other industrial and mining enterprises of steel structure and mechanical equipment, all kinds of storage tanks, pipelines such as the anti-corrosion of steel. Anti-corrosion steel pipe in our country's petroleum, chemical, gas, heating, sewage treatment, water supply, Bridges, steel structure and so on pipeline engineering fields have a wide range of applications.

If you are interested in coated carbon steel pipe,pls contact :hunan great steel pipe co.,ltd

Technical of Stainless Steel Pipe Production

At present, the stainless steel pipe production with perforation + cold rolling and cold drawing (including pickling and annealing) or perforated + hot rolled tube, cold rolling, cold drawing (including pickling and annealing), the process should be unique (including Taiwan province of China) in our country, and compared to the traditional extrusion + cold rolling, cold drawing process. Production cost is low, the wall thickness of high precision, but the middle process grinding amount is larger, this is due to the former procedure USES the punch, the expansion of tube billet surface defect quantity, after perforation caused by steel tube needs a large number of grinding, because of China's artificial cost is low, the processing method is more common in China.

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Situation of gas pipe

Cylinder pipe, accumulator pipe gas cylinder, accumulator of successful development, break through the traditional production method of cylinder, accumulator squeeze, raise the production efficiency greatly of cylinder, accumulator, and the surface quality of the product and wall thickness accuracy is improved. 2004 cylinder pipe, accumulator, the production of more than 100000 t, l % of the seamless steel pipe; Cylinder pipe through the difficult path of development, yield less than 50% from the early 80 s, up to now more than 80%. With the development of city gas taxi, right cylinder pipe demand will continue to increase. In addition, CNG station, trailer storage cylinder pipe and the accumulator (large diameter, medium thickness), will have a significant development. Domestic in recent years, also in the development, the current domestic couldn't produce this kind of air cylinder tube, but along with the construction of several large caliber unit, the supply of this kind of product will improve.

If you would like to know more about carbon steel pipe,pls contact :hunan great steel pipe co.,ltd

Development situation of line pipe

Line pipe With the development of the pipeline steel plate technology and the progress of welded pipe forming, welding technology, the application range of the pipe with welded pipe in gradually expanding, especially in the large diameter welded pipe class scope the advantage of more wet, and cost factors, welded pipe has been dominant in the field of line pipe, which limits the development of the seamless line pipe. About 2004 t 2004 seamless line pipe production, steel grade including X42-70, varieties have a land line pipe and seabed pipeline. The current production of high grade pipeline pipe is adopted micro alloying heat treatment process, the cost of production of seamless tube was obviously higher than that of welded pipe, and with the improvement of steel grade, such as the above X80 grade pipeline steel tube limits on carbon equivalent, seamless steel pipe of conventional technology is difficult to meet user requirements; Currently all seamless steel tube plant in order to improve the line pipe corrosion resistance, the use of stable performance and low temperature, high temperature environment to carry out the scientific research work.

If you would like to know more about carbon steel pipe,pls contact:hunan great steel pipe co.,ltd 

Welded Steel Pipe

In the form of welded steel pipe according to the weld seam welded pipe and SSAW steel pipe. Straight seam welded pipe production technology is simple, high production efficiency, low cost, rapid development. The strength of the spiral welded pipe is generally higher than straight seam welded pipe, use a narrow billet production of larger diameter welded pipe, you can also use the same width of billet in the production of different pipe diameter welded pipe. But compared with the same length of straight seam pipe, weld length by 30 ~ 100%, and the production speed is low. As a result, a small diameter welded pipe are mostly with straight seam welding, large diameter welded pipe for the most part adopts spiral welded. Low pressure fluid conveying in welded steel pipe is also called general welded pipe, commonly known as the clarinet. Is used to transport oil, gas, air, water and heating steam and other general low pressure fluid and other purposes of welded steel pipe. Steel tube wall thickness is divided into ordinary steel pipe and increasing pipe; To take over the side form is divided into without thread steel pipe (light pipe) and take rebar. Low pressure fluid conveying in welded steel pipe in addition to directly used for conveying fluid, also used as a low voltage large amounts of fluid conveying with galvanized welded steel pipe.

If you would like to know more about carbon steel pipe,pls contact:hunan great steel pipe co.,ltd

Seamless Steel Pipe Production Technology Development

Structure with seamless steel pipe production technology development began in the rise of the bicycle manufacturing, the early 19th century, the development of oil, during the two world wars ships, boiler, aircraft manufacturing, after the second world war thermal power boiler manufacturing, chemical industry and the development of oil and gas drilling and transportation, effectively driving the steel pipe industry in the development of varieties, yield and quality. Steel pipe used for conveying fluid and solid, not only to exchange heat, manufacturing machinery parts and container, it is also a kind of economic steel. With steel pipe manufacturing space truss structures, pillar and mechanical support, can reduce light weight, saving metal 20 ~ 40%, and can realize the mechanization of factory construction. With steel pipe manufacturing highway Bridges not only can save steel, simplify construction, and can greatly reduce the area of the coating layer, save investment and maintenance costs.

If you would like to know more about carbon steel pipe,pls contact:hunan great steel pipe co.,ltd

How to Choose Pressure Piping Metal Material

(1) the metal material selection of pressure piping metal material selection principle (1) meet the requirements of operating conditions First of all should be based on conditions of use to judge whether the pipeline under pressure, belong to which kind of pressure piping. Different categories of pressure pipeline because of the importance of each different, accident harm degree, also different to the requirement of material. At the same time, should consider the use environment and conveying pipeline medium and medium degree of corrosion of the pipe body. Inserted into the bottom of steel pipe pile, for example, the tube in the splash zone corrosion rate for six times in the seabed soil; Tidal range zone 4 times of corrosion rate of the seabed soil. On the material selection and corrosion protection measures should pay special attention. (2) the machinability for material should possess good processability and weldability. 3. Durable and economical pressure pipeline, first of all should be safe and durable and the economy. A device, a batch of pipeline engineering, before the investment selection, a feasibility study when necessary, the economic and technical analysis, intends to choose the material can be destiny, economic and technical analysis, some materials slightly higher initial investment, but the use of reliable, maintenance cost province at ordinary times; Initial investment appears to be some of the material, but the poor reliability in operation, the high cost of maintenance, at ordinary times the high cost of whole life cycle.

If you would like to know more about ERW steel pipe,pls contact us:hunan great steel pipe co.,ltd

The performance of the pipeline in the corrosive environment changes

Pipeline in the corrosive environment changes in petrochemical industry, the performance of pipeline media such as ships, offshore oil platform, a lot of corrosive, in fact, the dangers of metal corrosion is very common, but also is very serious, the corrosion cause direct or indirect losses. Metal, for example, the stress corrosion and corrosion fatigue and corrosion tend to major catastrophic accident, and the metal corrosion will cause a lot of metal consumption, waste lots of resources. Basically has the following several kinds of corrosion medium. 1) chloride and chloride corrosion of carbon steel pipe is basically uniform corrosion, and accompanied by hydrogen embrittlement, corrosion of stainless steel is pitting corrosion and intercrystalline corrosion. Prevention measures can choose appropriate materials, such as the use of carbon steel and stainless steel composite pipe. As many as 250 (2) sulfide sulfur in crude oil, on the metal corrosion of coating steel pipe hydrogen sulfide (H2S), mercaptan (R - SH), sulfide (R - S - R), etc. High H2S content in the liquefied petroleum gas in our country, causing cracks in container, some production of the 87 days that happen through cracks and later by the magnetic particle inspection, inner surface circumferential weld crack, 417 ball in vitro surface crack, so the high content of H2S stress corrosion caused by deserve attention. Japan

Welding society and high pressure gas safety association rules: H2S content in the liquefied oil should be controlled under 100 x 10-6, but our country liquefied petroleum gas H2S content in an average of 2392 x 10-6, Japan more than 20 times higher. (3) naphthenic acid naphthenic acid is of organic compounds in crude oil, when the temperature exceeds 220 ℃, began to occur corrosion, 270 ~ 280 ℃ maximum corrosion; When the temperature exceeds 400 ℃, the naphthenic acid in crude oil has finished vaporization. Stainless steel 316 l (00 cr17ni14mo2) is an effective material for naphthenic acid corrosion resistance, they can be used for high temperature naphthenic acid corrosion environment.

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The Change of Character in high temperature enviroment

Change (1) the performance of metal materials in high temperature creep at high temperature steel subjected to external forces, with the extension of time, slowly and continuously produce plastic deformation phenomenon, known as creep. Creep characteristics of steel has a great relationship with the temperature and stress. Temperature or stress increases, creep speed. The operating temperature of the carbon steel, for example, more than 300 ~ 350 ℃, alloy steel working temperature more than 300 ~ 400 ℃ will creep. The needed to generate creep stress below test temperature steel yield strength. Therefore, for long-term work under high temperature of boiler, steam pipe, pressure vessel steel should be used with good creep resistance, in order to prevent the large deformation caused by creep structure fracture and the malignant accident such as blast. (2) the spheroidizing and graphitization Under the effect of high temperature, the carbon steel cementite due to gain energy will take place in the migration and accumulation, the formation of coarse grains of cementite and inclusions in ferrite, the carburizing experience from flake gradually into a ball, called the ball. Due to the low intensity of graphite and flake, make the material strength greatly reduced, increased brittleness, referred to as the material of graphitization. Carbon steel is to work for a long time in more than 425 ℃ environment, graphitization occurs, the more obvious in higher than 475 ℃. Highest SH3059 regulation of carbon steel using temperature is 425 ℃, GB150 regulation of carbon steel using highest temperature is 450 ℃. (3) thermal fatigue performance If steel heating and work for a long time, so material under the action of internal thermal stress caused by changes in temperature, will produce tiny crack and expanding, finally lead to fracture. Therefore, changes in temperature and work structure, the pipe should be considered under the condition of the thermal fatigue properties of steel. (4) the material of high temperature oxidation of metal materials in high temperature oxidizing medium environment, such as flue will be oxidized and produce scale, crisp fall easily. Carbon steel at 570 ℃ high temperature gas variation in scale and make the metal thinning. Therefore, gas, flue pipe should be limited work under 560 ℃.

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How to Identification of fake seamless steel pipe

Fake seamless steel pipe identification method
The identification method and inferior steel pipe:
1. And inferior steel tube folding is seen. Folding is formed on the surface of the pipe line, this kind of defect often throughout the entire product longitudinal. Causes of fold is due to the pursuit of the false and inferior, high efficiency, large reduction, handle, when the next rolling produce folding, folding products will be cracking after bending, strength of steel.
(2) and inferior steel tube appearance often have pitted surface phenomenon. Pits was caused by worn groove steel irregular uneven defects. Because want to pursuit of profit and inferior steel pipe manufacturer, often appear groove rolling the overweight.
(3) and inferior steel tube surface are prone to scarring. For two reasons: (1) and inferior steel pipe material uneven, impurities. (2). And inferior manufacturer guide equipment simple, easy to stick steel, these impurities
4. Easy generation and inferior material surface crack, the reason is that it's blank is adobe, adobe air, adobe in cooling process due to the effect of thermal stress, cracks, after rolling there is crack.
5. Easy to scratch and inferior steel pipe, the reason is false and inferior steel pipe factory equipment simple, easy to produce burr, scratch steel surfaces. Deep scratches to reduce the strength of the steel.
6. No metallic luster and inferior steel tube, reddish, or two point two, the billet is adobe reasons. 2, and inferior material rolling temperature is not standard, their steel temperature is through visual inspection, so can't austenitic area of the rolling by the regulation, the performance of the steel natural can't up to standard.
7. And inferior steel pipe transverse reinforcement and low, often appear as disgruntled phenomenon, the reason was that the manufacturer for big minus tolerance, the finished product before several pressure
8 and inferior steel tube cross-section oval, because the factory in order to save material, the quantity of the finished product roll before 2 slants big, the strength of rebar is greatly decreased, but also do not conform to the standard of rebar shape size.
9. The high quality steel composition is uniform, cold shearing machine high tonnage, cutting head end face smooth and neat, and shoddy material because the material is poor, cutting head end face often have meat, or uneven, and no metallic luster. And because the manufacturers cut head, end there will be a big handle.
More than 10. And inferior impurities in steel pipe material, steel small density, size and do poorly in the absence of vernier caliper, can be checked to weigh it. Such as for rebar, 20 biggest minus tolerance specified in the national standard of 5%, scale 9 m in the theory of single weight is 120 kg, it should be the smallest weight: 120 X (l - 5%) = 114 kg, weigh out the weight of the single is smaller than 114 kilograms, is false and inferior steel %. In general the whole amount to match the effect will be better, mainly considering the cumulative error and probability theory to this problem.
11. And inferior steel pipe diameter is volatile, the reason is; L, the steel temperature instability has Yin and Yang. 2, the composition of steel is not uniform. 3, due to poorly equipped, foundation strength is low, mill's bounce. There will be a larger changes within the same week, the steel bar caused by uneven on fracture.
12. The high quality tube logo and printing are specification.
13. More than three steel pipe diameter 16 spacing are over IM.
14. And inferior steel rebar longitudinal reinforcement often undulate.

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Introduction of Converter Steelmaking

From the torpedo car shipped after hot metal desulphurization and slag treatment in converter as the main burden, 10% below the scrap. To burning in oxygen blowing of converter, then the excess carbon oxidized iron water and release a lot of heat, when the probe measured reaches a predetermined low carbon content, namely stop oxygen And out of the steel. Generally need a deoxidization and adjust the ingredients in the ladle operation; Then carbonized rice husk to prevent the molten steel in molten steel surface by oxidation, can be sent to continuous casting or die caster area.

Of high steel grade can increase the bottom blowing argon, RH vacuum treatment, powder spray (SI - CA powder and degeneration of lime) can effectively reduce the gases and inclusions in the steel, and have further to fall the action of carbon and sulfur. In these measures after refining outside the furnace can eventually fine ingredients, meet the needs of high quality steel.

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Stainless Steel Sheet Deep Drawing Characteristics and Tumor

stainless steel sheet deep drawing characteristics and tumor
Due to the high yield point stainless steel, high hardness, cold work hardening effect significantly, stainless steel sheet during deep drawing its characteristics as follows:
1) due to the poor thermal conductivity than normal low carbon steel, lead to the deformation force;
2) stainless steel sheet deep drawing, the severe plastic deformation hardening, wrinkle easily when the sheet deep drawing, need larger blank-holder force;
3) sheet metal deep drawing die in the rounded corners of bending and reverse bending springback, caused by deformation are usually formed in the product wall sag to demand higher dimensional accuracy and shape products need to increase the plastic process to achieve.
4) stainless steel sheet deep drawing process prone to caking phenomenon.
2 solutions.
2.1 working parts of die material selection and heat treatment
The practice proved: choose hard cast aluminum bronze, aluminum bronze anti-sticking effect is better; Manufactured carbonized tungsten steel bond hard alloy die than use Cr12Mov soft nitriding manufacturing the die life several times, and not sticky mode; If the code 3054 alloy cast iron, in the mold surface of flame quenching, the mold surface will not be binding. Also can be used in the mold damageable parts carbide edge, it has excellent compressive performance and superior wear resistance and lasting affection degree of surface roughness and size control. But due to the price, the production with less.
Restricted by plant material, if the general high carbon and high chromium steel used for stainless steel sheet deep drawing mould, heat treatment should reach more than 60 HRC hardness, surface soft nitriding process can be performed. Such as to improve the die wear and improve to hardness for deep drawing of stainless steel binding phenomenon will not improve. The key is to should as far as possible to remove residual austenite in the heat treatment, such as Cr12 common strain, fire technology on high hardness materials, even reach the extreme hardness range of HRC62-64, in the organization is still remaining a considerable amount of austenite. Soft point in the austenite is mould, compared with the martensite and lubricant of surfactant in the weaker affinity, is not easy to establish the lubricating film. So this kind of material heat treatment of low temperature processing can be used in strain, fire after cooling, the residual austenite into martensite and thus improve the resistance to adhesive matrix. In addition, still should make surface treatment for the stainless steel deep drawing mould to improve mould wear resistance, resistance to adhesive. For alloy cast iron and nonferrous alloy materials made of die surface strengthening technology, such as imposing nitriding use effect is good.
2.2 the surface of the mould work part machining
Low surface roughness can play the role of anti-friction and improve adhesion resistance accordingly. Cast in the whole process of mould processing, grinding amount shall be accounted for a third, because of the appearance of the stainless steel product quality depends largely on the mould cast grinding technology. In recent years, domestic appeared a new technology of polishing and polishing tools, developed ultrasonic, electrolytic polishing and abrasive jet, extrusion honing and other new technology, new equipment. , according to data of CrWMo, 3 cr12w8v, three kinds of Cr12 material mould of electrochemical polishing experiments, prove that the polishing in only 5 to 10 minutes to make the mold cavity surface roughness from the original on the basis of Ra3.2 - Ra1.6 down to Ra0.4 - RaO. 2. Through electrochemical polishing at the same time also can improve the surface hardness in order to improve the wear resistance. As another example, ultrasonic polishing machine can be used for the soft nitriding processing cavity fine polishing, it can avoid the shortcoming of manual polishing easy to destroy the nitride film. We should actively to use of a new polishing technology and summarized.

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Reaction of Stainless steel pipe And the gas

Hydrogen corrosion phenomena may occur in ammonia synthesis, hydrogen desulfurization hydrogenation and oil refining device. Carbon steel is not suitable for high pressure hydrogen device for above 232 ℃. The hydrogen diffusion into the steel, and in the grain boundary or pearlite zone and reaction of iron carbide and produce methane, the methane (gas) can't spread to the outside steel all together, and white spots and cracks in metal or one of them. In order to prevent to produce methane, cementite must replacement into stable carbide, chromium, vanadium, titanium, or must be added into the steel drill. Data points out, improve the chromium content allows the use of higher temperature and hydrogen partial pressure formed in the steel chrome carbide, and it encounters of hydrogen is stable. In the use of harsh conditions (temperature higher than 593 ℃), the chromium content is more than 12% chromium steel and austenitic stainless steel in all known applications are corrosion resistance.
Most metals and alloys at high temperature molecular nitrogen is unresponsive, but nitrogen atoms can react with many steel. And penetration into steel and the formation of a brittle nitrides surface layer. Iron, aluminum, titanium, chromium and other alloying elements may be involved in these reactions. The main source of nitrogen atoms are ammonia decomposition. Ammonia converter, the system of ammonia plant production of heater and in 371 ℃ ~ 593 ℃, a nitriding furnace under atmospheric pressure ~ 10.5 Kg/was have ammonia decomposition of the operation. In the atmosphere, in the low chrome steel chromium carbide. It may be affected by the corrosion of nitrogen atoms to produce chromium nitride, and release of the carbon and hydrogen to generate methane, as above, then possible to generate white spots and cracks, or one of them. But chrome content more than 12%, the carbides in the steel than chromium nitride is more stable, so the response will not appear in front of, so now the stainless steel used in the high temperature of hot ammonia environment.
Stainless steel in ammonia state depends on temperature, pressure, gas concentration of chromium and nickel content. Field experiment results showed that the ferrite and martensite stainless steel corrosion rate (alteration metal depth or carburized depth) is higher than austenitic stainless steel, the nickel content, the higher the better corrosion resistance. With the increase of content increased corrosion rate.

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T91 alloy steel tube elements

T91 alloy steel tube elements
T91 steel alloy elements in solid solution strengthening, dispersion strengthening and improving the oxidation resistance, corrosion resistance of steel, concrete analysis is as follows.
(1) carbon is a solid solution strengthening effect of the most obvious element in steel, with the increase of carbon content of steel rising short-term strength, plasticity and toughness drops, for T91 martensitic steel such, higher carbon content will speed up the carbide spheroidizing and aggregation, accelerate the redistribution of alloy elements, lower steel weldability, corrosion resistance and oxidation resistance, so the heat resistant steel is generally want to reduce the carbon content, but the low carbon, will reduce the strength of steel. T91 steel compared with 12 cr1mov steel, carbon content by 20%, this is a comprehensive consideration of the above factors.
(2) the T91 steel containing trace nitrogen, nitrogen effect is embodied in two aspects. Solid solution strengthening effect on one hand, the room temperature nitrogen solubility in the steel is very small, T91 steel after welding heat affected zone in welding heating and heat treatment after welding process, will be successively appeared.vn solid solution and precipitation process: welding heat affected zone has formed by heating of austenitic organization because of.vn into, nitrogen content, then the degree of supersaturation in normal temperature group increased, in the subsequent heat treatment after welding are tiny.vn precipitation, this increases the organization stability, improved the persistent strength values of heat affected zone. T91 steel, on the other hand, also contains a small amount of A1, the nitrogen to form A1N, A1N in 1 100 ℃ above a lot into the matrix, at lower temperatures and precipitation again, can have better dispersion strengthening effect.
(3) to join the chromium mainly is to improve the oxidation resistance, corrosion resistance of heat resistant steel, chromium content is less than 5%, to 600 ℃ began to severe oxidation, and chromium content of 5% has good oxidation resistance. 12 cr1mov steel under 580 ℃ has good oxidation resistance, corrosion depth is 0.05 mm/a, 600 ℃ when the performance starts to degrade corrosion depth is 0.13 mm/a. T91 chromium content increased to 9%, the use of temperature can reach 650 ℃, the main measure is to make the matrix of dissolve more chrome.
(4) vanadium and niobium are strong carbide forming elements, after joining can form a small and stable alloy carbide and carbon, has a strong dispersion strengthening effect.
(5) join molybdenum is mainly in order to improve the steel hot strong sex, have the effect of solid solution strengthening.
T91 alloy steel tube heat treatment process
The final heat treatment of T91 for high temperature tempering, normalizing + normalizing temperature is 1040 ℃, holding time not less than 10 min, tempering temperature is 730 ~ 780 ℃, holding time not less than 1 h, eventually organization for tempering martensite after heat treatment.
T91 alloy steel pipe mechanical properties
Of T91 steel at room temperature tensile strength of 585 MPa, or room temperature yield strength 415 MPa, or higher hardness HB 250 or less, elongation (50 mm gauge standard circular specimen) 20% or higher, the allowable stress values (sigma] 650 ℃ = 30 MPa.
T91 alloy steel pipe welding performance
According to the carbon equivalent formula is recommended by the international welding T91 carbon equivalent to the weldability of T91 is poorer.

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