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08-13-2011, 01:36 AM
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stainless steel (Stainless Steel) refers to the resistance of air, steam, water and other corrosive medium and weak acid, alkali, salt and other chemical attack by corrosive media, steel, also known as acid-resistant stainless steel. Practical applications, often the weak corrosion resistance as stainless steel, corrosion medium, and the chemical resistance of steel known as acid corrosion of steel. As the two differences in the chemical composition, the former does not necessarily chemical resistance corrosion, while the latter are generally of a stainless steel. The corrosion resistance of stainless steel depends on the alloying elements contained.
directory
I. Introduction II stainless steel, stainless steel, three of history, stainless steel effect four or five groups of stainless steel grade, corrosion-resistant stainless steel Why? Six, seven types of stainless steel, stainless steel, the advantage - eight atmospheric corrosion resistant, maintenance and clean-up nine, ten typical applications, the surface state of eleven, twelve future prospects, the identification method of stainless steel thirteen, fourteen of stainless steel, stainless steel surface damage and foreign objects entrained cleaning fifth, the physical properties of stainless steel and carbon steel data contrast XVI Seventeen mechanical properties of stainless steel, stainless steel features and uses (grades for the old standard) eighteen, nineteenth corrosion of stainless steel, stainless steel and Data comparing the physical properties of carbon steel twenty, stainless steel, stainless steel mesh belt
I. Introduction of stainless steel and all metals are the reaction of oxygen in the atmosphere, the surface oxide film. Unfortunately, the iron oxide formed on carbon steel continue to oxidation, corrosion constantly expanding, and ultimately the formation of holes. Can use paint or oxidation-resistant metals (eg, zinc, nickel and chromium) plating to protect the steel surface, but, as people know, this protection is only a film. If the protective layer is damaged, the following is a chromium steel began to rust corrosion resistance of stainless steel to obtain the basic elements, when the chromium content in steel up to 12%, the chromium and corrosive media, the role of oxygen in the steel surface to form a thin layer of oxide film (from the passive film), can prevent further corrosion of the steel substrate. In addition to chromium, the commonly used alloying elements nickel, molybdenum, titanium, niobium, copper, nitrogen, etc., to meet the various uses and properties of stainless steel requirements. Stainless steel is usually divided by the matrix: 1, ferritic stainless steel. 12% Chromium 30%. Its corrosion resistance, toughness and weldability with the increase of chromium content increased resistance to chloride stress corrosion better than other types of stainless steel. 2, austenitic stainless steel. More than 18% chromium, 8% also contains a small amount of nickel and molybdenum, titanium, nitrogen and other elements. Comprehensive performance, and can be resistant to a variety of media corrosion. 3, austenitic - ferritic duplex stainless steel. Both austenitic and ferritic stainless steel, the merits, and has superplasticity. 4, martensitic stainless steel. High strength, but poor ductility and weldability. Second, the stainless steel graduated from the University of Sheffield history, metallurgical scientists, famous Henry Blair Lee (Harry Brearley) in the early 20th century invented the stainless steel. The invention and use of stainless steel, dates back to World War I period. British scientists share 利布雷尔利 cloth military arsenal by the British government
stainless steel flagpoles
commission to study the weapons improvements. At that time, soldiers can easily use the rifle bore wear, mine Hurley would like to invent a scratch-resistant alloy steel. Brearly invented stainless steel in 1916, a British patent and began mass production, thus, came across from the garbage they swept the world of stainless steel, Henry Blair Lee is also known as the Third, the role of stainless steel, stainless steel, no corrosion, pitting, corrosion or wear. Stainless steel or metal materials used in construction materials in one of the highest intensity. Because stainless steel has good corrosion resistance, so it can permanently maintain the structural components of the integrity of engineering design. Chromium stainless steel is also set of mechanical strength and high elongation in one, easy-to-parts manufacturing to meet the architects and structural designers need to
stainless steel plate
. Fourth, precipitation hardening stainless steel grades of stainless steel group. Has good formability and good weldability, high strength materials can be used as the nuclear industry, aviation and aerospace industry applications. Cr components can be divided by line (400 series), Cr-Ni system (300 series), Cr-Mn-Ni (200 series) and precipitation hardening line (600 series). 200 - chromium - nickel - manganese 300 series austenitic stainless steel - chrome - nickel austenitic stainless steel 301 - ductile, for formed products. It can also be rapidly hardened by mechanical processing. Welding is good. Abrasion resistance and fatigue strength than 304 stainless steel. 302 - 304 with corrosion resistance, due to relatively high carbon intensity and therefore better. 303 - by adding a small amount of sulfur and phosphorus to more than 304 cutting. 304 - or 18 / 8 stainless steel. GB grades for 0Cr18Ni9. 309 - 304 better than the heat resistance. 316 - Following the 304, the second most widely used of steel, mainly for the food industry, pharmaceutical industry and surgical equipment, adding Mo to obtain a special corrosion-resistant structure. Better than the 304 because of its resistance to chloride corrosion and thus as SS316 is often used to fuel recovery. 18/10 grade stainless steel is usually in line with the application level. [1]
stainless steel buckets
Model 321 - not only because of the added titanium reduces the risk of corrosion of materials other than weld properties are similar to 304. 400 Series - Ferritic and martensitic stainless steel. 408 - good heat resistance, low corrosion resistance, 11% Cr, 8% of Ni. 409 - the cheapest model (England), commonly used as automobile exhaust pipe, is a ferritic stainless steel (chrome steel). 410 - martensite (high strength chrome steel), good wear resistance, corrosion resistance is poor. 416 - sulfur added to improve the processing properties of the material. 420 - Also used for surgical tools, can do very light. 430 - ferritic stainless steel, decorative, such as for car accessories. Good shape, but heat resistance and corrosion resistance worse. 440 - high strength cutting tool steel, carbon slightly higher, after appropriate heat treatment to obtain a higher yield strength and hardness up to 58HRC, are among the most hard stainless steel column. The most common application example is the There are three common models: 440A, 440B, 440C, in addition to 440F (and easy processing.) 500 Series - heat-resistant chromium alloy steel. 600 Series - martensitic precipitation hardening stainless steel.
stainless steel
630 - the most commonly used precipitation hardening stainless steel models, often called 17-4; 17% Cr, 4% Ni. V. Why is corrosion-resistant stainless steel? All metals and the reaction of oxygen in the atmosphere, chi turbo flat iron, in the surface oxide film. Unfortunately, the iron oxide formed on carbon steel continue to oxidation, corrosion constantly expanding, and ultimately the formation of holes. Can use paint or oxidation-resistant metals (eg, zinc, nickel and chromium) plating to ensure the steel surface, but, as people know, this protection is only a film. If the protective layer is damaged, the following steel began to rust.
stainless steel cookware
depends on the corrosion resistance of stainless steel, chromium, but because the chromium is one of the components of steel, so the protection methods vary. Add in the chrome above reached 11.7%, atmospheric corrosion resistant steel increased significantly, but the chromium content higher, although still improve corrosion resistance, but not obvious. The reason is steel with a chromium alloy processing, the type of change in the surface oxide into the metal is similar to pure chromium oxide formed on the surface. This tight adhesion of chromium-rich oxide to protect the surface against further oxidation. This very thin oxide layer, through which you can see the surface of the natural sheen of steel, the stainless steel has a unique surface. Moreover, if the damaged surface, the exposed steel surface and atmospheric response to self-repair, re-formation of this oxide Therefore, all the stainless steel elements have a common characteristic, namely, chromium content of 10.5% or more. Sixth, the type of stainless steel The key to success is to understand the purpose first, and then determine the correct steel. Further details of the stainless steel can be found compiled by the NiDI Fortunately, building construction and steel-related applications are usually only six. They contain 17 to 22% chromium, a better steel also contains nickel. Adding further to improve the atmospheric corrosion of molybdenum, in particular resistance to atmospheric corrosion with chloride
stainless steel
. Seven, the advantages of stainless steel - experience has shown that resistance to atmospheric corrosion, atmospheric corrosion from region to region. For illustration purposes, proposed to be divided into four regions, namely: rural, urban, industrial area and coastal areas. Is essentially pollution-free rural area. Low population density area, only non-polluting industries. A typical urban residential, commercial and light industrial areas, there is light pollution in the area, such as traffic pollution. Industrial air pollution caused by heavy industry area. Contamination may be due to the formation of fuel gases such as sulfur and nitrogen oxides, or the release of chemical or processing plant other gases. Particles suspended in air travel, such as iron and steel dust generated in the production process or the deposition of iron oxide corrosion will also increase. Coastal areas is usually less than a mile from the beach area. However, deep ocean-atmosphere can be spread to the inland, especially on the island, the prevailing winds from the ocean, and bad weather. For example, the British climate is the case, so the entire country belongs to the coastal area. If the wind mixed with the ocean mist, especially due to evaporation caused by deposition of salt concentration, coupled with less rain, less often by rainfall, coastal areas is even more unfavorable conditions. If there is industrial pollution, then the greater the corrosion. United States, Britain, France, Italy, Sweden and Australia carried out the research work has identified these areas for a variety of stainless steel resistant to atmospheric corrosion. The contents published in NiIDI Making choices, it is important to determine whether there are factors that affect the use of the local environment of the scene. For example, the stainless steel used in the bottom of the factory chimney, the exhaust air damper used in the scrap market near or near to have non-normal conditions. VIII, maintenance and cleaning, and other materials exposed to the atmosphere, like stainless steel will be dirty. Seminar will analyze the impact of future maintenance and clean-up cost design factors. However, rainfall, artificial irrigation and dirty between the surface there is also a mutual relationship. By the same slab directly on the atmosphere and stored in a shed where the effect of rainfall determined. The effect of artificial washing sponge with soapy water by hand with a scrub every six months the right side of each strip determined. It was found on a shelf with a place and not to be compared to the slab where washed by rain wash and manual scrubbing to remove surface dust and deposition on the surface, have a good effect. But also found that surface processing conditions also affect the smooth surface of the lath lath better than the rough surface area. Therefore, the time interval wash affected by many factors, the main factor is the required standards of beauty. Although many stainless steel walls is only cleaning the windows only to wash, but, in general, for external stainless steel wash twice a year. September, typical use most of the requirements for long-term use of the original appearance of the building. To be used in determining the type of stainless steel, the main consideration is the required standards of beauty, the location of atmospheric corrosion and clean-up system should be adopted. However, other more and more and more just looking for structural integrity or watertightness. For example, the roof and side walls of industrial buildings. In these applications, the owner of the construction costs may be more important than the aesthetic, the surface is not very clean also. In a dry indoor environment using 304 stainless steel results have been very good. However, in rural and urban areas in order to maintain its appearance in the outdoors, they need regular cleaning. In the heavily polluted industrial areas and coastal areas, the surface will be very dirty and even rust. Outdoor environment, but to get the aesthetic effect of nickel-containing stainless steel to be used. Therefore, 304 stainless steel is widely used in curtain wall, side walls, roof and other construction purposes, but in the erosion of serious industrial or marine atmosphere, preferably 316 stainless steel.
stainless steel sliding doors
Now, it has been fully aware of the use of stainless steel in structural applications superiority. There are several design criteria including the 304 and 316 stainless steel. Because the Shape of the product in fact, all stainless steel is the standard shape and size of metal manufacturing, but also many special shapes. The most commonly used product is made of sheet and strip, but also produce special products with a plate, for example, production of hot-rolled structural steel and structural steel extrusion. But also circular, oval, square, rectangular and hexagonal pipe or seamless steel tubes and other forms of products, including profiles, rods, wire and castings. Ten, surface state, as discussed later, in order to meet the aesthetic requirements of architects, has developed a wide variety of commercial surface processing. For example, the surface can be highly reflective or matte; can be smooth, polished or embossed; can be colored, color, plating, or stainless steel surface is etched with patterns, but also for drawing, etc. the appearance of the design staff to meet the various requirements. It is easy to maintain the surface state. Only occasional washing can remove the dust. As good corrosion resistance, but you can easily remove graffiti surface contamination or other similar surface contamination. XI, the future prospects of building materials as stainless steel have been required with many desirable properties, it can be said in the metal is unique, and its development continues. To enable the application of stainless steel in the traditional better performance, has been the improvement of existing types, and, in order to meet the stringent requirements of advanced construction applications, is developing a new stainless steel. Continuously improve the productivity, quality, continuous improvement, stainless steel has become the architect to choose the most cost-effective materials. Stainless steel set of performance, appearance and use of features in one, so the stainless steel will remain the world's best building material one. Second, stainless steel identification number and the method of representation: ① chemical element with the symbol of international and national symbols to represent the chemical composition, with the Arabic alphabet to represent the component content: such as: China, Russia 12CrNi3A ② fixed-digit numbers that steel type series or digital; such as: the United States, Japan, 300 series, 400 series, 200 series; ③ the order form with the Latin alphabet and number, saying only that purpose. The number of rules ① ② use of elemental symbols, Pinyin, open-hearth steel: P, boiling steel: F, killed steel: B, A steel: A, T8: Special 8, GCr15: Ball ◆ alloy steel, spring steel, such as: 20CrMnTi 60SiMn, (with very few that C content) ◆ stainless steel, alloy tool steel (with a few thousandths of that C content), such as: 1Cr18Ni9 thousandth (ie, 0.1% C), stainless steel C ≤ 0.08 % If 0Cr18Ni9, ultra-low carbon C ≤ 0.03% as 00Cr17Ni13Mo International Stainless Steel Plate method is to use three American Iron and Steel Institute figures indicate a variety of standard grade wrought stainless steel. Including: ① austenitic stainless steel with 200 and 300 series digital mark, for example, some of the more common austenitic stainless steel is 201, 304, 316 and 310 as a marker.
stainless steel
② Ferritic and martensitic stainless steel with a 400 series numerals. ③ ferritic stainless steel is marked 430 and 446, and 440C martensitic stainless steel as the tag is 410,420, two-phase (austenite - ferrite), ④ stainless steel, precipitation hardening stainless steel and low iron content 50% of high alloy usually uses proprietary name or trademark name. 4). Standard classification and grading of Classification 4-1: ① the national standard GB ② industry standard YB ③ ④ local standard enterprise standard Q / CB 4-2 Category: ① ② product standard method of standard packaging standard ③ ④ basic standards 4-3 standard level (three levels): Y-level: the international advanced level I level: the general level of H international level: the advanced level in national standard GB1220-84 4-4 stainless steel rod (I grade) GB4241-84 stainless steel welded plate Park ( H-level) GB4356-84 stainless steel welded plate garden (I grade) GB1270-80 stainless steel pipe (I class) GB12771-91 stainless steel pipe (Y class) GB3280-84 stainless steel cold plate (I grade) GB4237-84 stainless steel hot plate (I grade) GB4239-91 stainless steel cold strip (I level) XIII, acid-resistant stainless steel stainless steel stainless steel short, it is acid-resistant steel, stainless steel and composed of two parts, in short, to resist the atmospheric corrosion of stainless steel is called, and resistance to chemical corrosion of steel called the acid medium of steel. In general, with Ge content greater than 12% of the steel Wcr on the characteristics of stainless steel with a stainless steel microstructure by heat treatment can be divided into five categories: namely, ferritic stainless steel, martensitic stainless steel, austenitic stainless steel austenitic - ferritic stainless steel and precipitation of carbon steel equipment, the text will appear in the performance of the production process damage, defects, and some of the surface material, such as: dust, iron or embedded floating iron, hot temper color, and other oxide, CHI Pink Dazzle Flat Iron, rust, grinding burrs, welding arc mark, weld spatter, flux, welding defects, oil and grease, residual adhesive and paint, chalk and marker pen and Indian. Most of all because they ignored the harmful effects of attention or not doing a good job. However, they have a protective film on the oxidation potential hazards. Once the protective film is damaged, thinning or other methods to make the change, the following will start the corrosion of stainless steel. Corrosion is generally not over the entire surface, but at or around the defect. The Board, usually pitting corrosion or crevice corrosion, the two corrosive to the depth and breadth, and most of the surface from erosion. Here to talk about the various reasons for these problems. Fourth, stainless steel surface damage and foreign objects entrained cleaning a dust production is often carried out in a field of dust, the air often with a lot of dust, they continue to fall on surfaces. They can be removed with water or alkaline solution. However, adhesion of dust needed to clean up high-pressure water or steam. 2, floating iron or embedded in any surface of iron, free iron, stainless steel will rust and make cause corrosion. Therefore, must be removed. IRES generally removed along with the dust. Some of adhesion is very strong, must be embedded in the iron treatment. In addition to dust, the surface of many sources of iron, including the use of ordinary carbon steel wire brush clean-up and use previously in carbon steel, low alloy steel or cast iron pieces used sand, glass beads or other abrasive blasting treatment, or stainless steel parts and equipment in the vicinity of the previously mentioned non-stainless steel products for grinding. Hanging over the next course of material or stainless steel if not take measures to protect wire rope, slings and iron table surface is easy to embed or tarnished surface. After the inspection requirements and production orders can prevent and detect the presence of free iron, ASTM standard A380 [3] provides for inspection of stainless steel particles of iron or steel surface rust test. When iron requirements must not exist, it should use this test. If the results are satisfactory, the application of clean water or nitric acid washing the surface until the deep blue disappeared. As the standard A380 [3] pointed out that if the rust test solution can not be fully cleaned, the process is not recommended in the device surface, which used to produce consumer goods, direct contact with the surface of human use of this test method. Relatively simple test method is exposed in the water 12 to 24 hours to check for rust spots. The test sensitivity is poor, and time-consuming. These are testing, not the clean-up methods. If you find that the existence of iron, must be behind the introduction of chemical and electrochemical methods to clean up. 3, process lubricant to prevent scratches or the resultant and / or dirt accumulates, you must rough surface scratches and other mechanical cleaning (such as dry sand blasting, abrasive glass beads). 4, hot temper color, and other oxide layer if the process of welding or grinding of stainless steel in the air is heated to a certain temperature, the weld on both sides of the weld will appear under the surface and the bottom of the hot temper and color of chromium oxide . Color than the thermal annealing of thin oxide protective film, and visible. Color depends on thickness, can be presented rainbow colors, blue, purple to yellow and brown. Thick oxide is black. It is due to high temperature or long stay in the more highly induced under. When any of these oxide layer, the metal surface will reduce the chromium content, resulting in reduced corrosion resistance of these regions. In this case, not only to remove color and other thermal annealing oxide layer, but also deal with them following the poor to clean up chromium metal layer. 5, rust pre-production or production process can sometimes see the rust on stainless steel products or equipment, indicating that the surface is seriously contaminated. Equipment put into use before the rust removed, thoroughly cleaned surfaces should be through the iron test and / or water test inspection. 6, coarse grinding and grinding and machining machining can cause surface roughness, leaving grooves, overlapping and burrs. Each defect may also damage the metal surface to a certain depth, so that the metal surface can not be damaged by acid pickling, CHI Turbo Ceramic Flat Iron, polishing or shot peening (such as dry sand blasting, abrasive glass beads) were used to clean out. Rough surface happened to be the birthplace of resultant corrosion and deposition, re-weld defects before trimming or removing excess weld can not strengthen the high coarse grinding. In the latter case, should then fine abrasive grinding. 7, trace arc welding arc welders in the metal surface, the surface roughness will cause defects. Protective film damage, leaving a potential source of corrosion. Should have a good welder welding welding trail or in the arc side of the weld joints. And then melt into the weld arc traces. 8, the welding spatter welding spatter and welding a great relationship. For example: GTAM (Gas Tungsten Arc Welding) or TIG (tungsten inert gas welding) is not flying. However, the use of GMAW (Gas Metal Arc Welding) and FCAW (flux cored arc welding with) when the two welding processes welding parameters if used improperly can cause a lot of splash. When this occurs, you must adjust the parameters. If you want to solve the problem of weld spatter, weld joints before the splash agent coated on each side, so you can eliminate spatter adhesion. After welding of this kind can easily splash out cleaning agents and a variety of flying objects, do not damage the surface or have minimal damage. 9, the flux flux welding process using a manual welding with flux cored arc welding and submerged arc welding process which will leave a small flux in the surface of particles, general clean-up methods can not be rid of them. This is the particle will be the source of corrosion crevice corrosion, mechanical cleaning methods must be used to remove these residual flux. 10, welded welding defects such as: undercut, incomplete penetration, dense pores and cracks not only reduce the firmness of joints, but also become a source of corrosion crevice corrosion. Clean-up operation to improve the results, they also entrained solids. These defects can be re-re-welding or grinding after welding to repair. 11, organic substances such as oil and grease: oil, grease and even fingerprints will become a source of localized corrosion of corrosion. Because these substances can play a barrier role, they will affect the chemical and electrochemical cleaning effect, which must be thoroughly cleared away. ASTM A380 has a simple shutoff (WATERBREAK) test for detection of organic pollutants. Test, poured from the top of the vertical surface of the water, the process to the downstream flow of water out around the separation of organic matter. Flux and / or acidic chemical cleaning agents can remove traces of oil and grease. 12, residual adhesive tear tape and protect the paper, the adhesive part of the total residue in the stainless steel surface. If you stick all agents not hard, you can use to remove organic solvent. However, when exposed to light and / or air, stick the whole agent hardens to form a corrosion crevice corrosion source. Then need to use fine abrasive mechanical cleaning. 13, paint, chalk and marker pen and India the impact of these pollutants and oil and grease were similar. Proposed to use a clean brush and clean water for washing or alkaline cleaning agent, you can also use high-pressure water or steam flushing.
Hard 301 Stainless Steel
in the use of state to ferrite-based stainless steel. Chromium content of 11% to 30%, with a body-centered cubic crystal structure. Such steels typically contain nickel, sometimes also contains a small amount of Mo, Ti, Nb wait until the element, type of steel with a large thermal conductivity, expansion coefficient, good oxidation resistance, excellent resistance to stress corrosion, etc., are used for manufacture of air resistance , steam, water and oxidizing acid corrosion components. The existence of such steel plastic poor ductility and corrosion resistance after welding and other shortcomings significantly reduced, thus limiting its application. Refining Technology (AOD or VOD) applications enable carbon, nitrogen and other elements greatly reduce the gap, thus making such steel is widely used. Fifth, the physical properties of stainless steel and carbon steel comparison of the data slightly higher than the density of carbon steel and martensitic ferritic stainless steel, chi iron, but slightly lower than the austenitic stainless steel; resistivity of carbon steel, ferrite, martensite-type Sort Ascending and austenitic stainless steel; linear expansion coefficient of the order is similar, while the carbon austenitic stainless steel highest minimum; carbon steel, ferrite and martensite stainless steel is magnetic, austenitic stainless steel is not magnetic, but cold hardening of martensitic phase transformation generated will produce magnetic, heat treatment method can be used to eliminate this martensite was restored to its non-magnetic. Austenitic stainless steel and carbon steel compared with the following characteristics: 1) high resistivity, about 5 times the carbon steel. 2) The large linear expansion coefficient, 40% larger than the carbon steel and the increase of temperature, linear expansion coefficient values are also increased accordingly. 3) low thermal conductivity, carbon steel is about 1 / 3. Sixteen, regardless of mechanical properties of stainless steel or heat-resistant stainless steel plate, austenitic steel plate the best overall performance, both adequate strength, have excellent hardness of the plastic while not high, which is they are widely used One of the reasons. Austenitic stainless steel with the most similar to other metal materials, the tensile strength, yield strength and hardness increased with decreasing temperature; plasticity is reduced as the temperature decreases. The tensile strength in the temperature range of 15 ~ 80 ° C in growth is more uniform. More important: As the temperature decreases, the impact toughness decreased slowly, there is no brittle transition temperature. So stainless steel at low temperature to maintain sufficient plasticity and toughness. Heat resistance of stainless steel is the high temperature heat resistance, both anti-oxidation or corrosion-resistant properties of the gas medium thermal stability, while at high temperatures and adequate strength double that of heat intensity. Carbon: carbon in the austenitic stainless steel is strong and stable austenite formation and expansion of austenite elements. The ability of carbon to austenite is about 30 times that of nickel, carbon is an interstitial element, through the solid solution strengthening can significantly improve the strength of austenitic stainless steel. carbon austenitic stainless steel can be increased in the high concentration of chloride (eg, boiling 42% MgCl2 solution) in the resistance to stress corrosion. However, in austenitic stainless steel , often seen as harmful elements of carbon, mainly due to the use of stainless steel and corrosion of some conditions (such as welding or heating after 450 ~ 850 ℃), carbon can form a high chromium steel chromium Cr23C6 Carbon chromium compounds, resulting in partial depletion of the corrosion resistance of the steel in particular, decreased resistance to intergranular corrosion. Therefore, new developments since the 60's chrome-nickel austenitic stainless steel are mostly carbon content of less than 0.03% or 0.02% over low-carbon, and to know the carbon content decreased susceptibility to intergranular corrosion of steel lower carbon content below 0.02% when it has the most significant results, some experimental pearl also noted that carbon will increase the chromium austenitic pitting corrosion of stainless steel body of sub-trend. Because the harmful effects of carbon, not only in austenitic stainless steel smelting control over and shall be required in the carbon content as low as possible, and in the subsequent heat, cold and heat treatment process is also to prevent the stainless steel the surface of carbon, and chromium carbide precipitation-free. chrome effect: chromium austenitic stainless steel is the most important alloying elements in austenitic stainless steel and corrosion resistance will be mainly due to mass effect , the chromium passivation of steel and to promote the stable passive state of steel results. ○ 1 Chromium impact on the organization: in austenitic stainless steels, chromium is a strong and stable form of iron element in the body, reduce austenite With increasing content of steel, stainless steel can occur in the ferrite (δ) organizations, research shows that, in the chrome-nickel austenitic stainless steel, when the carbon content of 0.1%, 18% chromium content, in order to single stable austenite, the required minimum nickel content of about 8% to this point, 18Cr-8Ni type commonly used chrome-nickel austenitic stainless steel is chromium, nickel ratio of one of the most appropriate species. There austenitic stainless steel, with the chromium content increases, the number of intermetallic phases (such as δ-phase) formation tendency to increase, when the steel contains molybdenum, the chromium content will increase with the formation will be equal to χ, As mentioned above, σ, χ-phase precipitation is not only significantly reduce the plasticity and toughness, and in some conditions, also reduces the corrosion resistance of steel, austenitic stainless martensitic chromium can increase the temperature hydrocarbon transfer (Ms) decreased, thereby improving the stability of the austenitic matrix. Thus the high Chromium (eg, more than 20%) even after the cold stainless steel and low temperature martensite is also difficult to obtain .. the formation of chromium carbides is a strong elements, is no exception in the austenitic stainless steel, austenitic stainless steel of chromium carbide are common Cr23C6; When the steel contains molybdenum or chromium, can still see on Cr6C other carbides and their formation under certain conditions the performance of the steel under a major impact. ○ 2 on the properties of Cr: General to the Lord, as long as remain fully austenitic stainless steel without δ ferrite formation, etc., chi pink dazzle, only enhance the chromium content in steel is not will significantly affect the mechanical properties, chromium greatest impact on the performance of austenitic stainless steel is corrosion resistance, mainly as follows: chromium improve the oxidation resistance of steel and acid chloride media media performance; in the nickel and molybdenum and copper compound under the action of chromium steel resistant to a number of reduction to improve the media, organic acids, urea and alkaline media performance; chromium also improves resistance to localized corrosion of steel, such as intergranular corrosion. pitting corrosion, crevice corrosion and stress under these conditions in a stadium performance. . austenitic stainless steels of sensitivity between the sports biggest factor is the carbon content in steel, other elements of the role of intergranular Stadium as its primary carbides dissolution and precipitation behavior, depending on the austenitic stainless steel , the chromium can increase the solubility of carbon decreases the degree of chromium depleted, thus increasing chromium content in the austenitic stainless steel is a good resistance to intergranular corrosion, chromium is very effective in improving pitting corrosion resistance of austenitic stainless steel and crevice corrosion performance, when steel while molybdenum or molybdenum and nitrogen are present, a large chrome to enhance the effectiveness of this, although the study of molybdenum and crevice corrosion resistance point of stadium capacity, then times of chromium and nitrogen as chromium 30 times But the large number of studies, austenitic stainless steel without chromium or chromium content is low, molybdenum and nitrogen corrosion and crevice corrosion resistance point of the role will lose or not significant. chromium austenitic stainless steel stress corrosion resistance of the role of with the experimental medium conditions and the actual use of the environment vary in boiling MgCl2 solution, the role of chromium is generally harmful, but in the Cl-and oxygen containing aqueous medium, high temperature and pressure, and pitting for the origin of water stress corrosion conditions increase of chromium content in steel is beneficial for stress corrosion resistance, while also preventing chromium alloy austenitic stainless steel and nickel content increased as the type prone to intergranular stress corrosion tendency, off caustic (NqOH) stress corrosion, The role of chromium Chromium is also beneficial to the body in addition to the negative's important influence the corrosion resistance of stainless steel, but also can significantly improve the type of steel antioxidant, curing and anti-corrosion properties of molten salt. Nickel is in the austenitic stainless steel major alloying element, its main role is a million and stabilize austenite, so that steel is fully austenitic, so that the steel has good strength and ductility, toughness of the match, and has excellent cold and hot and cold processing formative as well as welding, low and non-magnetic and other properties, while increasing the thermodynamic stability of the austenitic stainless steel, so that not only the same ratio of chromium and molybdenum content of ferrite and martensite, and the like are willing to have a better stainless steel and oxidation resistance properties of the medium, and increased stability in the surface film, so that the steel also has excellent resistance to a number of more reducing the performance of the media. 1 Organization of Nickel Nickel is a million strong and stable austenite austenite phase region and the expansion of the elements, chi pink dazzle hair straightener, in order to obtain a single austenite, when the steel contains 0.1% carbon and 18% of the minimum required for nickel-chromium content of about 8%, this is the most famous 18-8 Cr-Ni austenitic stainless steel base points, stainless steel, with the nickel content increases, the residual ferrite can be completely eliminated, and significantly reduce the tendency of the formation of σ phase; also lower the temperature of martensite turn hydrocarbons, do not even appear λ → M phase transition, but the increase of nickel content reduces the carbon solubility in austenite stainless steel, so that the tendency of carbide precipitation increased. 2 on the performance of nickel-nickel austenitic stainless steel, especially for chromium 2. 3. 4. 5. 6. 7. 8. 9. 10. 12. 13. 14. 15. 16. 17. 20. 21. 24. 25. 28. 29. 30. 31. 36. 42. 46. 47. 48. 49. 51. 52. 53. |
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08-13-2011, 01:37 AM
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stainless steel (Stainless Steel) refers to the resistance of air, steam, water and other corrosive medium and weak acid, alkali, salt and other chemical attack by corrosive media, steel, also known as acid-resistant stainless steel. Practical applications, often the weak corrosion resistance as stainless steel, corrosion medium, and the chemical resistance of steel known as acid corrosion of steel. As the two differences in the chemical composition, the former does not necessarily chemical resistance corrosion, while the latter are generally of a stainless steel. The corrosion resistance of stainless steel depends on the alloying elements contained.
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I. Introduction II stainless steel, stainless steel, three of history, stainless steel effect four or five groups of stainless steel grade, corrosion-resistant stainless steel Why? Six, seven types of stainless steel, stainless steel, the advantage - eight atmospheric corrosion resistant, maintenance and clean-up nine, ten typical applications, the surface state of eleven, twelve future prospects, the identification method of stainless steel thirteen, fourteen of stainless steel, stainless steel surface damage and foreign objects entrained cleaning fifth, the physical properties of stainless steel and carbon steel data contrast XVI Seventeen mechanical properties of stainless steel, stainless steel features and uses (grades for the old standard) eighteen, nineteenth corrosion of stainless steel, stainless steel and Data comparing the physical properties of carbon steel twenty, stainless steel, stainless steel mesh belt
I. Introduction of stainless steel and all metals are the reaction of oxygen in the atmosphere, the surface oxide film. Unfortunately, the iron oxide formed on carbon steel continue to oxidation, corrosion constantly expanding, and ultimately the formation of holes. Can use paint or oxidation-resistant metals (eg, zinc, nickel and chromium) plating to protect the steel surface, but, as people know, this protection is only a film. If the protective layer is damaged, the following is a chromium steel began to rust corrosion resistance of stainless steel to obtain the basic elements, when the chromium content in steel up to 12%, the chromium and corrosive media, the role of oxygen in the steel surface to form a thin layer of oxide film (from the passive film), can prevent further corrosion of the steel substrate. In addition to chromium, the commonly used alloying elements nickel, molybdenum, titanium, niobium, copper, nitrogen, etc., to meet the various uses and properties of stainless steel requirements. Stainless steel is usually divided by the matrix: 1, ferritic stainless steel. 12% Chromium 30%. Its corrosion resistance, toughness and weldability with the increase of chromium content increased resistance to chloride stress corrosion better than other types of stainless steel. 2, austenitic stainless steel. More than 18% chromium, 8% also contains a small amount of nickel and molybdenum, titanium, nitrogen and other elements. Comprehensive performance, and can be resistant to a variety of media corrosion. 3, austenitic - ferritic duplex stainless steel. Both austenitic and ferritic stainless steel, the merits, and has superplasticity. 4, martensitic stainless steel. High strength, but poor ductility and weldability. Second, the stainless steel graduated from the University of Sheffield history, metallurgical scientists, famous Henry Blair Lee (Harry Brearley) in the early 20th century invented the stainless steel. The invention and use of stainless steel, dates back to World War I period. British scientists share 利布雷尔利 cloth military arsenal by the British government
stainless steel flagpoles
commission to study the weapons improvements. At that time, soldiers can easily use the rifle bore wear, mine Hurley would like to invent a scratch-resistant alloy steel. Brearly invented stainless steel in 1916, a British patent and began mass production, thus, came across from the garbage they swept the world of stainless steel, Henry Blair Lee is also known as the Third, the role of stainless steel, stainless steel, no corrosion, pitting, corrosion or wear. Stainless steel or metal materials used in construction materials in one of the highest intensity. Because stainless steel has good corrosion resistance, so it can permanently maintain the structural components of the integrity of engineering design. Chromium stainless steel is also set of mechanical strength and high elongation in one, easy-to-parts manufacturing to meet the architects and structural designers need to
stainless steel plate
. Fourth, precipitation hardening stainless steel grades of stainless steel group. Has good formability and good weldability, high strength materials can be used as the nuclear industry, aviation and aerospace industry applications. Cr components can be divided by line (400 series), Cr-Ni system (300 series), Cr-Mn-Ni (200 series) and precipitation hardening line (600 series). 200 - chromium - nickel - manganese 300 series austenitic stainless steel - chrome - nickel austenitic stainless steel 301 - ductile, for formed products. It can also be rapidly hardened by mechanical processing. Welding is good. Abrasion resistance and fatigue strength than 304 stainless steel. 302 - 304 with corrosion resistance, due to relatively high carbon intensity and therefore better. 303 - by adding a small amount of sulfur and phosphorus to more than 304 cutting. 304 - or 18 / 8 stainless steel. GB grades for 0Cr18Ni9. 309 - 304 better than the heat resistance. 316 - Following the 304, the second most widely used of steel, mainly for the food industry, pharmaceutical industry and surgical equipment, adding Mo to obtain a special corrosion-resistant structure. Better than the 304 because of its resistance to chloride corrosion and thus as SS316 is often used to fuel recovery. 18/10 grade stainless steel is usually in line with the application level. [1]
stainless steel buckets
Model 321 - not only because of the added titanium reduces the risk of corrosion of materials other than weld properties are similar to 304. 400 Series - Ferritic and martensitic stainless steel. 408 - good heat resistance, low corrosion resistance, 11% Cr, 8% of Ni. 409 - the cheapest model (England), commonly used as automobile exhaust pipe, is a ferritic stainless steel (chrome steel). 410 - martensite (high strength chrome steel), good wear resistance, corrosion resistance is poor. 416 - sulfur added to improve the processing properties of the material. 420 - Also used for surgical tools, can do very light. 430 - ferritic stainless steel, decorative, such as for car accessories. Good shape, but heat resistance and corrosion resistance worse. 440 - high strength cutting tool steel, carbon slightly higher, after appropriate heat treatment to obtain a higher yield strength and hardness up to 58HRC, are among the most hard stainless steel column. The most common application example is the There are three common models: 440A, 440B, 440C, in addition to 440F (and easy processing.) 500 Series - heat-resistant chromium alloy steel. 600 Series - martensitic precipitation hardening stainless steel.
stainless steel
630 - the most commonly used precipitation hardening stainless steel models, often called 17-4; 17% Cr, 4% Ni. V. Why is corrosion-resistant stainless steel? All metals and the reaction of oxygen in the atmosphere, chi turbo flat iron, in the surface oxide film. Unfortunately, the iron oxide formed on carbon steel continue to oxidation, corrosion constantly expanding, and ultimately the formation of holes. Can use paint or oxidation-resistant metals (eg, zinc, nickel and chromium) plating to ensure the steel surface, but, as people know, this protection is only a film. If the protective layer is damaged, the following steel began to rust.
stainless steel cookware
depends on the corrosion resistance of stainless steel, chromium, but because the chromium is one of the components of steel, so the protection methods vary. Add in the chrome above reached 11.7%, atmospheric corrosion resistant steel increased significantly, but the chromium content higher, although still improve corrosion resistance, but not obvious. The reason is steel with a chromium alloy processing, the type of change in the surface oxide into the metal is similar to pure chromium oxide formed on the surface. This tight adhesion of chromium-rich oxide to protect the surface against further oxidation. This very thin oxide layer, through which you can see the surface of the natural sheen of steel, the stainless steel has a unique surface. Moreover, if the damaged surface, the exposed steel surface and atmospheric response to self-repair, re-formation of this oxide Therefore, all the stainless steel elements have a common characteristic, namely, chromium content of 10.5% or more. Sixth, the type of stainless steel The key to success is to understand the purpose first, and then determine the correct steel. Further details of the stainless steel can be found compiled by the NiDI Fortunately, building construction and steel-related applications are usually only six. They contain 17 to 22% chromium, a better steel also contains nickel. Adding further to improve the atmospheric corrosion of molybdenum, in particular resistance to atmospheric corrosion with chloride
stainless steel
. Seven, the advantages of stainless steel - experience has shown that resistance to atmospheric corrosion, atmospheric corrosion from region to region. For illustration purposes, proposed to be divided into four regions, namely: rural, urban, industrial area and coastal areas. Is essentially pollution-free rural area. Low population density area, only non-polluting industries. A typical urban residential, commercial and light industrial areas, there is light pollution in the area, such as traffic pollution. Industrial air pollution caused by heavy industry area. Contamination may be due to the formation of fuel gases such as sulfur and nitrogen oxides, or the release of chemical or processing plant other gases. Particles suspended in air travel, such as iron and steel dust generated in the production process or the deposition of iron oxide corrosion will also increase. Coastal areas is usually less than a mile from the beach area. However, deep ocean-atmosphere can be spread to the inland, especially on the island, the prevailing winds from the ocean, and bad weather. For example, the British climate is the case, so the entire country belongs to the coastal area. If the wind mixed with the ocean mist, especially due to evaporation caused by deposition of salt concentration, coupled with less rain, less often by rainfall, coastal areas is even more unfavorable conditions. If there is industrial pollution, then the greater the corrosion. United States, Britain, France, Italy, Sweden and Australia carried out the research work has identified these areas for a variety of stainless steel resistant to atmospheric corrosion. The contents published in NiIDI Making choices, it is important to determine whether there are factors that affect the use of the local environment of the scene. For example, the stainless steel used in the bottom of the factory chimney, the exhaust air damper used in the scrap market near or near to have non-normal conditions. VIII, maintenance and cleaning, and other materials exposed to the atmosphere, like stainless steel will be dirty. Seminar will analyze the impact of future maintenance and clean-up cost design factors. However, rainfall, artificial irrigation and dirty between the surface there is also a mutual relationship. By the same slab directly on the atmosphere and stored in a shed where the effect of rainfall determined. The effect of artificial washing sponge with soapy water by hand with a scrub every six months the right side of each strip determined. It was found on a shelf with a place and not to be compared to the slab where washed by rain wash and manual scrubbing to remove surface dust and deposition on the surface, have a good effect. But also found that surface processing conditions also affect the smooth surface of the lath lath better than the rough surface area. Therefore, the time interval wash affected by many factors, the main factor is the required standards of beauty. Although many stainless steel walls is only cleaning the windows only to wash, but, in general, for external stainless steel wash twice a year. September, typical use most of the requirements for long-term use of the original appearance of the building. To be used in determining the type of stainless steel, the main consideration is the required standards of beauty, the location of atmospheric corrosion and clean-up system should be adopted. However, other more and more and more just looking for structural integrity or watertightness. For example, the roof and side walls of industrial buildings. In these applications, the owner of the construction costs may be more important than the aesthetic, the surface is not very clean also. In a dry indoor environment using 304 stainless steel results have been very good. However, in rural and urban areas in order to maintain its appearance in the outdoors, they need regular cleaning. In the heavily polluted industrial areas and coastal areas, the surface will be very dirty and even rust. Outdoor environment, but to get the aesthetic effect of nickel-containing stainless steel to be used. Therefore, 304 stainless steel is widely used in curtain wall, side walls, roof and other construction purposes, but in the erosion of serious industrial or marine atmosphere, preferably 316 stainless steel.
stainless steel sliding doors
Now, it has been fully aware of the use of stainless steel in structural applications superiority. There are several design criteria including the 304 and 316 stainless steel. Because the Shape of the product in fact, all stainless steel is the standard shape and size of metal manufacturing, but also many special shapes. The most commonly used product is made of sheet and strip, but also produce special products with a plate, for example, production of hot-rolled structural steel and structural steel extrusion. But also circular, oval, square, rectangular and hexagonal pipe or seamless steel tubes and other forms of products, including profiles, rods, wire and castings. Ten, surface state, as discussed later, in order to meet the aesthetic requirements of architects, has developed a wide variety of commercial surface processing. For example, the surface can be highly reflective or matte; can be smooth, polished or embossed; can be colored, color, plating, or stainless steel surface is etched with patterns, but also for drawing, etc. the appearance of the design staff to meet the various requirements. It is easy to maintain the surface state. Only occasional washing can remove the dust. As good corrosion resistance, but you can easily remove graffiti surface contamination or other similar surface contamination. XI, the future prospects of building materials as stainless steel have been required with many desirable properties, it can be said in the metal is unique, and its development continues. To enable the application of stainless steel in the traditional better performance, has been the improvement of existing types, and, in order to meet the stringent requirements of advanced construction applications, is developing a new stainless steel. Continuously improve the productivity, quality, continuous improvement, stainless steel has become the architect to choose the most cost-effective materials. Stainless steel set of performance, appearance and use of features in one, so the stainless steel will remain the world's best building material one. Second, stainless steel identification number and the method of representation: ① chemical element with the symbol of international and national symbols to represent the chemical composition, with the Arabic alphabet to represent the component content: such as: China, Russia 12CrNi3A ② fixed-digit numbers that steel type series or digital; such as: the United States, Japan, 300 series, 400 series, 200 series; ③ the order form with the Latin alphabet and number, saying only that purpose. The number of rules ① ② use of elemental symbols, Pinyin, open-hearth steel: P, boiling steel: F, killed steel: B, A steel: A, T8: Special 8, GCr15: Ball ◆ alloy steel, spring steel, such as: 20CrMnTi 60SiMn, (with very few that C content) ◆ stainless steel, alloy tool steel (with a few thousandths of that C content), such as: 1Cr18Ni9 thousandth (ie, 0.1% C), stainless steel C ≤ 0.08 % If 0Cr18Ni9, ultra-low carbon C ≤ 0.03% as 00Cr17Ni13Mo International Stainless Steel Plate method is to use three American Iron and Steel Institute figures indicate a variety of standard grade wrought stainless steel. Including: ① austenitic stainless steel with 200 and 300 series digital mark, for example, some of the more common austenitic stainless steel is 201, 304, 316 and 310 as a marker.
stainless steel
② Ferritic and martensitic stainless steel with a 400 series numerals. ③ ferritic stainless steel is marked 430 and 446, and 440C martensitic stainless steel as the tag is 410,420, two-phase (austenite - ferrite), ④ stainless steel, precipitation hardening stainless steel and low iron content 50% of high alloy usually uses proprietary name or trademark name. 4). Standard classification and grading of Classification 4-1: ① the national standard GB ② industry standard YB ③ ④ local standard enterprise standard Q / CB 4-2 Category: ① ② product standard method of standard packaging standard ③ ④ basic standards 4-3 standard level (three levels): Y-level: the international advanced level I level: the general level of H international level: the advanced level in national standard GB1220-84 4-4 stainless steel rod (I grade) GB4241-84 stainless steel welded plate Park ( H-level) GB4356-84 stainless steel welded plate garden (I grade) GB1270-80 stainless steel pipe (I class) GB12771-91 stainless steel pipe (Y class) GB3280-84 stainless steel cold plate (I grade) GB4237-84 stainless steel hot plate (I grade) GB4239-91 stainless steel cold strip (I level) XIII, acid-resistant stainless steel stainless steel stainless steel short, it is acid-resistant steel, stainless steel and composed of two parts, in short, to resist the atmospheric corrosion of stainless steel is called, and resistance to chemical corrosion of steel called the acid medium of steel. In general, with Ge content greater than 12% of the steel Wcr on the characteristics of stainless steel with a stainless steel microstructure by heat treatment can be divided into five categories: namely, ferritic stainless steel, martensitic stainless steel, austenitic stainless steel austenitic - ferritic stainless steel and precipitation of carbon steel equipment, the text will appear in the performance of the production process damage, defects, and some of the surface material, such as: dust, iron or embedded floating iron, hot temper color, and other oxide, CHI Pink Dazzle Flat Iron, rust, grinding burrs, welding arc mark, weld spatter, flux, welding defects, oil and grease, residual adhesive and paint, chalk and marker pen and Indian. Most of all because they ignored the harmful effects of attention or not doing a good job. However, they have a protective film on the oxidation potential hazards. Once the protective film is damaged, thinning or other methods to make the change, the following will start the corrosion of stainless steel. Corrosion is generally not over the entire surface, but at or around the defect. The Board, usually pitting corrosion or crevice corrosion, the two corrosive to the depth and breadth, and most of the surface from erosion. Here to talk about the various reasons for these problems. Fourth, stainless steel surface damage and foreign objects entrained cleaning a dust production is often carried out in a field of dust, the air often with a lot of dust, they continue to fall on surfaces. They can be removed with water or alkaline solution. However, adhesion of dust needed to clean up high-pressure water or steam. 2, floating iron or embedded in any surface of iron, free iron, stainless steel will rust and make cause corrosion. Therefore, must be removed. IRES generally removed along with the dust. Some of adhesion is very strong, must be embedded in the iron treatment. In addition to dust, the surface of many sources of iron, including the use of ordinary carbon steel wire brush clean-up and use previously in carbon steel, low alloy steel or cast iron pieces used sand, glass beads or other abrasive blasting treatment, or stainless steel parts and equipment in the vicinity of the previously mentioned non-stainless steel products for grinding. Hanging over the next course of material or stainless steel if not take measures to protect wire rope, slings and iron table surface is easy to embed or tarnished surface. After the inspection requirements and production orders can prevent and detect the presence of free iron, ASTM standard A380 [3] provides for inspection of stainless steel particles of iron or steel surface rust test. When iron requirements must not exist, it should use this test. If the results are satisfactory, the application of clean water or nitric acid washing the surface until the deep blue disappeared. As the standard A380 [3] pointed out that if the rust test solution can not be fully cleaned, the process is not recommended in the device surface, which used to produce consumer goods, direct contact with the surface of human use of this test method. Relatively simple test method is exposed in the water 12 to 24 hours to check for rust spots. The test sensitivity is poor, and time-consuming. These are testing, not the clean-up methods. If you find that the existence of iron, must be behind the introduction of chemical and electrochemical methods to clean up. 3, process lubricant to prevent scratches or the resultant and / or dirt accumulates, you must rough surface scratches and other mechanical cleaning (such as dry sand blasting, abrasive glass beads). 4, hot temper color, and other oxide layer if the process of welding or grinding of stainless steel in the air is heated to a certain temperature, the weld on both sides of the weld will appear under the surface and the bottom of the hot temper and color of chromium oxide . Color than the thermal annealing of thin oxide protective film, and visible. Color depends on thickness, can be presented rainbow colors, blue, purple to yellow and brown. Thick oxide is black. It is due to high temperature or long stay in the more highly induced under. When any of these oxide layer, the metal surface will reduce the chromium content, resulting in reduced corrosion resistance of these regions. In this case, not only to remove color and other thermal annealing oxide layer, but also deal with them following the poor to clean up chromium metal layer. 5, rust pre-production or production process can sometimes see the rust on stainless steel products or equipment, indicating that the surface is seriously contaminated. Equipment put into use before the rust removed, thoroughly cleaned surfaces should be through the iron test and / or water test inspection. 6, coarse grinding and grinding and machining machining can cause surface roughness, leaving grooves, overlapping and burrs. Each defect may also damage the metal surface to a certain depth, so that the metal surface can not be damaged by acid pickling, CHI Turbo Ceramic Flat Iron, polishing or shot peening (such as dry sand blasting, abrasive glass beads) were used to clean out. Rough surface happened to be the birthplace of resultant corrosion and deposition, re-weld defects before trimming or removing excess weld can not strengthen the high coarse grinding. In the latter case, should then fine abrasive grinding. 7, trace arc welding arc welders in the metal surface, the surface roughness will cause defects. Protective film damage, leaving a potential source of corrosion. Should have a good welder welding welding trail or in the arc side of the weld joints. And then melt into the weld arc traces. 8, the welding spatter welding spatter and welding a great relationship. For example: GTAM (Gas Tungsten Arc Welding) or TIG (tungsten inert gas welding) is not flying. However, the use of GMAW (Gas Metal Arc Welding) and FCAW (flux cored arc welding with) when the two welding processes welding parameters if used improperly can cause a lot of splash. When this occurs, you must adjust the parameters. If you want to solve the problem of weld spatter, weld joints before the splash agent coated on each side, so you can eliminate spatter adhesion. After welding of this kind can easily splash out cleaning agents and a variety of flying objects, do not damage the surface or have minimal damage. 9, the flux flux welding process using a manual welding with flux cored arc welding and submerged arc welding process which will leave a small flux in the surface of particles, general clean-up methods can not be rid of them. This is the particle will be the source of corrosion crevice corrosion, mechanical cleaning methods must be used to remove these residual flux. 10, welded welding defects such as: undercut, incomplete penetration, dense pores and cracks not only reduce the firmness of joints, but also become a source of corrosion crevice corrosion. Clean-up operation to improve the results, they also entrained solids. These defects can be re-re-welding or grinding after welding to repair. 11, organic substances such as oil and grease: oil, grease and even fingerprints will become a source of localized corrosion of corrosion. Because these substances can play a barrier role, they will affect the chemical and electrochemical cleaning effect, which must be thoroughly cleared away. ASTM A380 has a simple shutoff (WATERBREAK) test for detection of organic pollutants. Test, poured from the top of the vertical surface of the water, the process to the downstream flow of water out around the separation of organic matter. Flux and / or acidic chemical cleaning agents can remove traces of oil and grease. 12, residual adhesive tear tape and protect the paper, the adhesive part of the total residue in the stainless steel surface. If you stick all agents not hard, you can use to remove organic solvent. However, when exposed to light and / or air, stick the whole agent hardens to form a corrosion crevice corrosion source. Then need to use fine abrasive mechanical cleaning. 13, paint, chalk and marker pen and India the impact of these pollutants and oil and grease were similar. Proposed to use a clean brush and clean water for washing or alkaline cleaning agent, you can also use high-pressure water or steam flushing.
Hard 301 Stainless Steel
in the use of state to ferrite-based stainless steel. Chromium content of 11% to 30%, with a body-centered cubic crystal structure. Such steels typically contain nickel, sometimes also contains a small amount of Mo, Ti, Nb wait until the element, type of steel with a large thermal conductivity, expansion coefficient, good oxidation resistance, excellent resistance to stress corrosion, etc., are used for manufacture of air resistance , steam, water and oxidizing acid corrosion components. The existence of such steel plastic poor ductility and corrosion resistance after welding and other shortcomings significantly reduced, thus limiting its application. Refining Technology (AOD or VOD) applications enable carbon, nitrogen and other elements greatly reduce the gap, thus making such steel is widely used. Fifth, the physical properties of stainless steel and carbon steel comparison of the data slightly higher than the density of carbon steel and martensitic ferritic stainless steel, chi iron, but slightly lower than the austenitic stainless steel; resistivity of carbon steel, ferrite, martensite-type Sort Ascending and austenitic stainless steel; linear expansion coefficient of the order is similar, while the carbon austenitic stainless steel highest minimum; carbon steel, ferrite and martensite stainless steel is magnetic, austenitic stainless steel is not magnetic, but cold hardening of martensitic phase transformation generated will produce magnetic, heat treatment method can be used to eliminate this martensite was restored to its non-magnetic. Austenitic stainless steel and carbon steel compared with the following characteristics: 1) high resistivity, about 5 times the carbon steel. 2) The large linear expansion coefficient, 40% larger than the carbon steel and the increase of temperature, linear expansion coefficient values are also increased accordingly. 3) low thermal conductivity, carbon steel is about 1 / 3. Sixteen, regardless of mechanical properties of stainless steel or heat-resistant stainless steel plate, austenitic steel plate the best overall performance, both adequate strength, have excellent hardness of the plastic while not high, which is they are widely used One of the reasons. Austenitic stainless steel with the most similar to other metal materials, the tensile strength, yield strength and hardness increased with decreasing temperature; plasticity is reduced as the temperature decreases. The tensile strength in the temperature range of 15 ~ 80 ° C in growth is more uniform. More important: As the temperature decreases, the impact toughness decreased slowly, there is no brittle transition temperature. So stainless steel at low temperature to maintain sufficient plasticity and toughness. Heat resistance of stainless steel is the high temperature heat resistance, both anti-oxidation or corrosion-resistant properties of the gas medium thermal stability, while at high temperatures and adequate strength double that of heat intensity. Carbon: carbon in the austenitic stainless steel is strong and stable austenite formation and expansion of austenite elements. The ability of carbon to austenite is about 30 times that of nickel, carbon is an interstitial element, through the solid solution strengthening can significantly improve the strength of austenitic stainless steel. carbon austenitic stainless steel can be increased in the high concentration of chloride (eg, boiling 42% MgCl2 solution) in the resistance to stress corrosion. However, in austenitic stainless steel , often seen as harmful elements of carbon, mainly due to the use of stainless steel and corrosion of some conditions (such as welding or heating after 450 ~ 850 ℃), carbon can form a high chromium steel chromium Cr23C6 Carbon chromium compounds, resulting in partial depletion of the corrosion resistance of the steel in particular, decreased resistance to intergranular corrosion. Therefore, new developments since the 60's chrome-nickel austenitic stainless steel are mostly carbon content of less than 0.03% or 0.02% over low-carbon, and to know the carbon content decreased susceptibility to intergranular corrosion of steel lower carbon content below 0.02% when it has the most significant results, some experimental pearl also noted that carbon will increase the chromium austenitic pitting corrosion of stainless steel body of sub-trend. Because the harmful effects of carbon, not only in austenitic stainless steel smelting control over and shall be required in the carbon content as low as possible, and in the subsequent heat, cold and heat treatment process is also to prevent the stainless steel the surface of carbon, and chromium carbide precipitation-free. chrome effect: chromium austenitic stainless steel is the most important alloying elements in austenitic stainless steel and corrosion resistance will be mainly due to mass effect , the chromium passivation of steel and to promote the stable passive state of steel results. ○ 1 Chromium impact on the organization: in austenitic stainless steels, chromium is a strong and stable form of iron element in the body, reduce austenite With increasing content of steel, stainless steel can occur in the ferrite (δ) organizations, research shows that, in the chrome-nickel austenitic stainless steel, when the carbon content of 0.1%, 18% chromium content, in order to single stable austenite, the required minimum nickel content of about 8% to this point, 18Cr-8Ni type commonly used chrome-nickel austenitic stainless steel is chromium, nickel ratio of one of the most appropriate species. There austenitic stainless steel, with the chromium content increases, the number of intermetallic phases (such as δ-phase) formation tendency to increase, when the steel contains molybdenum, the chromium content will increase with the formation will be equal to χ, As mentioned above, σ, χ-phase precipitation is not only significantly reduce the plasticity and toughness, and in some conditions, also reduces the corrosion resistance of steel, austenitic stainless martensitic chromium can increase the temperature hydrocarbon transfer (Ms) decreased, thereby improving the stability of the austenitic matrix. Thus the high Chromium (eg, more than 20%) even after the cold stainless steel and low temperature martensite is also difficult to obtain .. the formation of chromium carbides is a strong elements, is no exception in the austenitic stainless steel, austenitic stainless steel of chromium carbide are common Cr23C6; When the steel contains molybdenum or chromium, can still see on Cr6C other carbides and their formation under certain conditions the performance of the steel under a major impact. ○ 2 on the properties of Cr: General to the Lord, as long as remain fully austenitic stainless steel without δ ferrite formation, etc., chi pink dazzle, only enhance the chromium content in steel is not will significantly affect the mechanical properties, chromium greatest impact on the performance of austenitic stainless steel is corrosion resistance, mainly as follows: chromium improve the oxidation resistance of steel and acid chloride media media performance; in the nickel and molybdenum and copper compound under the action of chromium steel resistant to a number of reduction to improve the media, organic acids, urea and alkaline media performance; chromium also improves resistance to localized corrosion of steel, such as intergranular corrosion. pitting corrosion, crevice corrosion and stress under these conditions in a stadium performance. . austenitic stainless steels of sensitivity between the sports biggest factor is the carbon content in steel, other elements of the role of intergranular Stadium as its primary carbides dissolution and precipitation behavior, depending on the austenitic stainless steel , the chromium can increase the solubility of carbon decreases the degree of chromium depleted, thus increasing chromium content in the austenitic stainless steel is a good resistance to intergranular corrosion, chromium is very effective in improving pitting corrosion resistance of austenitic stainless steel and crevice corrosion performance, when steel while molybdenum or molybdenum and nitrogen are present, a large chrome to enhance the effectiveness of this, although the study of molybdenum and crevice corrosion resistance point of stadium capacity, then times of chromium and nitrogen as chromium 30 times But the large number of studies, austenitic stainless steel without chromium or chromium content is low, molybdenum and nitrogen corrosion and crevice corrosion resistance point of the role will lose or not significant. chromium austenitic stainless steel stress corrosion resistance of the role of with the experimental medium conditions and the actual use of the environment vary in boiling MgCl2 solution, the role of chromium is generally harmful, but in the Cl-and oxygen containing aqueous medium, high temperature and pressure, and pitting for the origin of water stress corrosion conditions increase of chromium content in steel is beneficial for stress corrosion resistance, while also preventing chromium alloy austenitic stainless steel and nickel content increased as the type prone to intergranular stress corrosion tendency, off caustic (NqOH) stress corrosion, The role of chromium Chromium is also beneficial to the body in addition to the negative's important influence the corrosion resistance of stainless steel, but also can significantly improve the type of steel antioxidant, curing and anti-corrosion properties of molten salt. Nickel is in the austenitic stainless steel major alloying element, its main role is a million and stabilize austenite, so that steel is fully austenitic, so that the steel has good strength and ductility, toughness of the match, and has excellent cold and hot and cold processing formative as well as welding, low and non-magnetic and other properties, while increasing the thermodynamic stability of the austenitic stainless steel, so that not only the same ratio of chromium and molybdenum content of ferrite and martensite, and the like are willing to have a better stainless steel and oxidation resistance properties of the medium, and increased stability in the surface film, so that the steel also has excellent resistance to a number of more reducing the performance of the media. 1 Organization of Nickel Nickel is a million strong and stable austenite austenite phase region and the expansion of the elements, chi pink dazzle hair straightener, in order to obtain a single austenite, when the steel contains 0.1% carbon and 18% of the minimum required for nickel-chromium content of about 8%, this is the most famous 18-8 Cr-Ni austenitic stainless steel base points, stainless steel, with the nickel content increases, the residual ferrite can be completely eliminated, and significantly reduce the tendency of the formation of σ phase; also lower the temperature of martensite turn hydrocarbons, do not even appear λ → M phase transition, but the increase of nickel content reduces the carbon solubility in austenite stainless steel, so that the tendency of carbide precipitation increased. 2 on the performance of nickel-nickel austenitic stainless steel, especially for chromium 2. 3. 4. 5. 6. 7. 8. 9. 10. 12. 13. 14. 15. 16. 17. 20. 21. 24. 25. 28. 29. 30. 31. 36. 42. 46. 47. 48. 49. 51. 52. 53. |
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