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1, What is the stainless iron? Iron and stainless steel stainless What is the difference?
2, The meaning and classification of corrosion of stainless steel?
3, stainless steel selection factors to be considered?
4, Mo austenitic stainless steel on the impact?
5, Nickel on the impact of stainless steel?
6, chromium effects on austenitic stainless steel?
7, Carbon on the impact of austenitic stainless steel?
8, stainless steel, the physical properties, mechanical properties and heat resistance?
9, the corrosion resistance of stainless steel?
10, stainless steel professional terms Xiangjie?
11, also with magnetic stainless steel Why?
12,the corrosion resistance of stainless steel?
13, AISI, ASTM standards and the UNS system stainless steel and heat-resistant steel and chemical composition (mass fraction)【%】
14,stainless steel features and uses
15, JIS standards and common stainless steel chemical composition
16, China GB standard stainless steel rod and chemical composition (mass fraction) 【%
 
1,What is the stainless iron? Iron and stainless steel stainless What is the difference?
A: chromium steel is higher than 12.5%, with high resistance to external media (acid, alkali salt) corrosion of the steel, as stainless steel. According to the organization within the state of steel, stainless steel can be divided into martensite-type, ferrite size, austenitic, ferritic - austenitic, precipitation hardened stainless steel, according to the provisions of the national standard GB3280-92, a total of 55 regulations. In daily life we have more contact with austenitic stainless steel (some call it nickel-stainless steel) and Markov-type stainless steel (some call it stainless iron) two categories. Austenitic stainless steel grades for the typical 0Cr18Ni9, that is, "304" and 1Cr18Ni9Ti. Martensitic stainless steel that we produce stainless steel knives, scissors, grades mainly 2Cr13, 3Cr13, 6Cr13, 7Cr17 so. Since the composition of these two different stainless steel so that it is not the same built-metal microstructure. Austenitic stainless steel due to the higher chromium and nickel added (about 18% of chromium, Ni 4% or more), the steel presents a kind of internal organization of organizations called austenite state, this organization is not permeability and can not be attracted to a magnet. Often used as decorative materials, such as turbine blades, cutlery type, nozzle, valve seats, valves, measuring tools, bearings and so on. Made of stainless steel scissors type martensitic stainless steel to be used. Because scissors have cut items feature, you must have sharpness, sharpness must be a certain hardness. These stainless steel heat treatment must occur within the organization to change. Increase the hardness before making scissors. But such internal martensite stainless steel, with permeability, can be a magnet to attract. Therefore we can not simply whether there is magnetic to illustrate the stainless steel.
2, the meaning and classification of corrosion of stainless steel?
A: In the corrosive environment, the metal with the surrounding medium due to the chemical or electrochemical action is called the damage caused by corrosion.
In the corrosive environment, when the stainless steel choose not to then, it will also cause corrosion.
There are many classification corrosion.
1. According to the nature of the role can be divided into chemical and electrochemical corrosion.
2. By corrosion of the form can be divided into general (comprehensive, uniform) corrosion. The so-called general corrosion, corrosion of the distribution system measures the entire stainless steel surface, the so-called localized corrosion, pitting, crevice corrosion, stress corrosion, corrosion fatigue, selective corrosion, erosion and corrosion.
3. By corrosion occurred in the environment and conditions can be divided into atmospheric corrosion, corrosion of industrial water and soil erosion. Acids, alkalis. Salt corrosion, seawater corrosion, high temperature corrosion, (including liquid metals, molten salt, gas corrosion), etc..
3, stainless steel selection factors to be considered?
A: The choice of stainless steel in corrosive environment, in addition to the specific conditions of use of stainless steel should have a detailed understanding, but also major factors to consider are: stainless steel for corrosion resistance, strength, toughness, and physical properties, processing, formability, resources, price and ease of access.
1. Corrosion resistance
Corrosion resistance, including stainless and acid, alkali and salt corrosion medium performance and high temperature anti-oxidation, sulfide, chloride, fluoride and other performance. As the use of different stainless steel is mainly to solve practical engineering experience in the a variety of corrosion problems, for stainless steel in corrosive environment the corrosion resistance to a selection of staff first need to consider. Corrosion of metal and dielectric between the role of chemical or electrochemical damage caused, and that the corrosion resistance of stainless steel to resist media corrosion damage ability, so when the selection involved in the corrosion resistance, the need to pay attention to the following points.
1. Corrosion resistance of the standard is artificial, we must recognize it and use it, can not be bound by it, according to the specific requirements to use specific criteria to determine whether corrosion.
The corrosion resistance of stainless steel at present more than a 10-class standards, choose one as a corrosion-resistant requirements, to consider the equipment, the Department of months of characteristics (thickness, size). The length of life, product quality (such as impurities, color, purity) and other requirements, in general, the process required the use of clean mirror or size of sophisticated instrumentation and equipment parts, can choose from 1 to 3 standards; on the close coordination required, long-term limit does not leak or require the use of long equipment Select 2 to 5 parts, easy maintenance, or to request a less demanding life of the equipment is not very long, components can be selected from 4 to 7, except for special exceptions, conditions in the use of stainless steel corrosion rate of 1mm are generally not used more requires that the 10 standards for the production of local corrosion is not applicable.
2. Corrosion resistance is relative, conditional, and often speak of stainless steel, corrosion resistance relative to the pointing system and do not rust corrosion, means under certain conditions (medium, concentration, temperature, impurities, pressure, flow rate is fixed). So far, no corrosion in any environment, both with stainless steel, corrosion resistance of stainless steel, so option heart wood staff to be selected for the specific conditions of use, stainless steel grade selected, use the selected sector but also for the proper use of the characteristics of stainless steel, which increases the proper use of a reasonable selection to achieve a corrosion-resistant stainless steel or the purpose of .3. choice of stainless steel it is necessary to consider the performance of its resistance to general corrosion , but also consider the performance of its resistance to localized corrosion, in some medium of water and chemicals, the latter needs to be note that this is because the selection of personnel and more attention to the general resistance to general corrosion of stainless steel, while in use, they on the localized corrosion, such as stress corrosion pitting in the sensitivity to be considered less; localized corrosion of stainless steel and more corrosion-resistant common good corrosion occurs, often leading to localized corrosion of stainless steel equipment, parts of the sudden destruction of The danger is far greater than the general corrosion .4. in the application of the manuals in the corrosion resistance of stainless steel data, many of them to pay attention to some experimental data only within the test results, and actual media environment, often have greater access, In order to get closer to the actual conditions of use of corrosion data, should generally be conducted in the laboratory corrosion test of the actual medium or field conditions when In some conditions of use, will encounter this , when it is medium in or which produce industrial products in, Ji Shi Wei Liang's Mou Zhonghuo with a Cibuxiugang of metal ions O'clock, will be impacting the chemical processes Gong Gong Ye the quality of products (including gloss, color, purity, etc.). The situation of nuclear fuel and other pharmaceutical and paint industries, the most common, often used at this time without some element of stainless steel or an appropriate choice to improve the corrosion resistance of stainless steel grade, so that the metal ions down to the limits allowed.
5. Stainless steel equipment, parts Ruoyin corrosion and failure, it should be analysis of the causes of corrosion damage, identify the reason for the measures taken, and not fling is over.
4, Mo austenitic stainless steel on the impact?
A: Generally speaking, a simple chrome-nickel (and chromium manganese N) austenitic stainless steel used only for requirements and resistance to oxidative medium (such as nitric acid, etc.) under conditions of use molybdenum as the austenitic stainless steel in important alloying elements added to steel to further expand the scope of use, mainly to increase the role of molybdenum steel in the reductive medium (ratio of H2SO4, H3PO4, and some organic acids and urea environment) corrosion resistance, and increase the resistance point of steel corrosion and crevice corrosion properties.
1 Mo on the Structure of
Molybdenum and chromium are the formation and stability of ferrite and ferrite phase region to expand the elements, the formation of ferrite molybdenum and chromium considerable ability. Molybdenum also promotes intermetallic phase in austenitic stainless steel, such as σ phase,, κ phase, and Laves equal precipitation on the corrosion resistance of steel and mechanical properties will be adversely affected, goodbye is leading to plasticity, toughness decrease, for the austenitic stainless steel to maintain a single organization, with the molybdenum content in steel increase in austenite forming elements (nickel, nitrogen, and manganese, etc.) were also correspondingly increased to maintain the steel in the formation of ferrite and austenite, the balance between elements.
2 on the Properties of Molybdenum
Molybdenum oxidation of austenitic stainless steel was not significant, so when chromium nickel austenitic stainless steel to maintain a single austenite and no intermetallic precipitates, the addition of Mo has little effect on its mechanical properties at room temperature, but as Mo content increases, increase high temperature strength of steel, such as durable, and creep properties were greatly improved, therefore, often containing molybdenum stainless steel high temperature applications, however, the addition of molybdenum high temperature deformation resistance of the steel increases, coupled with there is often a small amount of steel in the δ ferrite stainless steel containing molybdenum and therefore keen workability for the poor than the non-molybdenum steel, and the higher molybdenum content, the more bad thermal processing performance, while containing molybdenum austenitic stainless steel is easy to 1,000,000 κ (σ) phase precipitation, which would significantly worsen the plasticity and toughness of steel, the austenitic stainless steel containing molybdenum production, equipment manufacturing and application process, we must guard against steel the formation of intermetallic phases.
Molybdenum in austenitic stainless steel primary role is to enhance resistance to reducing media and resistance to pitting corrosion, crevice corrosion resistance performance. Were molybdenum chromium nickel austenitic stainless steel in nitric acid, sulfuric acid, acetic acid, phosphate and urea, and other media in corrosion resistance, can be seen, except in the oxidizing medium HNO3 in the office, the role of molybdenum are useful, so ordinary austenitic stainless steel containing molybdenum nitric acid corrosion resistance without day, except nitric acid containing F-, Cl-, plasma,
Although the role of the alloying element molybdenum austenitic stainless steels in reducing medium, surface pitting and crevice corrosion of the reasons are not entirely clear, but a large number of experiments have pointed out that the role of molybdenum in the corrosion of steel contains only a relatively high amount of chromium when effective, molybdenum is mainly to strengthen the role of steel corrosion resistance of chromium at the same time, molybdenum, after the formation of salt corrosion inhibition has also been confirmed by the experiment.
Resistant to high concentration of chloride in the solution of stress corrosion, although the molybdenum as alloying elements on austenitic stainless steels in reducing medium, resistance to pitting corrosion and crevice corrosion of the reasons are not entirely clear, but a large number of experiments have pointed out that the only role of molybdenum When the steel contains higher levels of chromium when effective, molybdenum is mainly to strengthen the role of steel corrosion resistance of chromium, while the formation of molybdate molybdenum role after the buffer has been confirmed by experiments.
Resistance to degradation in the high concentration of chloride stress corrosion, although this experiment refers to a .3 # below with molybdenum austenitic stainless steel stress corrosion resistance of harmful, but because of common chrome-nickel austenitic stainless steel containing more than trace chloride and oxygen in the water saturated medium used, and their stress corrosion Youyi point for the origin of corrosion, so nickel-chromium with molybdenum as molybdenum austenitic stainless steel corrosion resistant high point, so in practical applications often than not contain molybdenum steel has better resistance to chloride stress corrosion.
5, Nickel on the impact of stainless steel?
A: Ni austenitic stainless steel is the main alloying element, its main role is a million and stability of austenite, the steel was fully austenitic, so that steel has good strength and ductility, toughness of the match, and excellent cold, heat and cold forming process and welding of low temperature and no magnetic 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 so willing to have a better class of stainless steel and resistance to oxidative medium of performance, but also in the surface film stability, thereby making more steel also has excellent resistance to the performance of some reductive medium.
1 Nickel impact on the organization
Nickel is one million strong and stable austenite phase region of austenite and expand the elements, 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 %, which is the most famous 18-8 chromium nickel austenitic stainless steel's basic points, austenitic stainless steel, with the increase of nickel content, the residual ferrite can be completely eliminated, and significantly reduce the tendency of the formation of σ phase ; also lower the temperature hydrocarbon transfer martensite, even from time to occur λ → M phase transition, but the increase will reduce the nickel content of carbon solubility in austenite stainless steel, so that carbide precipitation tend to increase.
2 on the Properties of Nickel
Nickel austenitic chrome-nickel stainless steel especially for negative body's mechanical properties of stainless steel is mainly on the austenite stability of nickel determined in steel martensite transformation may occur in the context of the nickel content, with the the nickel content increases the strength of steel reduced page plasticity increases with stable austenite chromium-nickel austenitic stainless steel toughness (including the extremely low temperature toughness) is very good, which can be used as a low-temperature steel, which is well known, for with stable austenite Cr-Mn austenitic stainless steel, nickel, adding further to improve its toughness. Nickel can also significantly reduce the tendency of austenitic stainless steel of cold hardening, which was mainly due to the stability of austenite increases, reducing even eliminate the cold martensite transformation in the process, while cold hardening on the role of austenite itself is not clear, cold hardening tendency of stainless steel, nickel austenitic stainless steel cold hardening rate decreased with lower temperature and low temperature steel strength, enhance the role of plasticity and decided to increase the nickel content is conducive to the cold formability of austenitic stainless steel, nickel content increased to reduce and even eliminate also 18-8 and 17-14-2 clamp-type chromium-nickel-9) Albright of stainless steel in the δ ferrite to enhance the thermal processing performance, but, δ ferrite to reduce the availability of these soldering of steel will increase the negative wire welding hot cracking tendency, in addition, nickel, chromium can significantly improve Mn and N (Cr Mn Ni N) austenitic stainless steel thermal processing performance, and thus significantly improve rate of finished steel
In the austenitic stainless steel, nickel, and with the addition of nickel content increased, resulting in increased thermodynamic stability of steel, the austenitic stainless steel has better resistance and oxidation resistance properties of the medium, and with Ni increased, the resistance to reducing media performance further improved. It is worth noting, nickel or austenitic stainless steel to improve wear resistance in many media crystal the only important element of stress corrosion.
Acid medium in a variety of nickel on the corrosion resistance of austenitic stainless steel, require that some of the water in the high temperature and pressure conditions, the nickel content of steel and the improvement of lead-based alloys intergranular stress corrosion susceptibility increases, but this kind of adverse effect will be as steel and alloy chromium content increased and was reduced or inhibited. with magnetic stainless steel in nickel content increases, the intergranular corrosion of critical lower carbon content, that is sensitive to intergranular corrosion of steel of increase, as pitting corrosion of austenitic stainless steel and crevice corrosion resistance performance, the role of nickel is not significant, in addition, nickel austenitic stainless steel also improves high temperature oxidation resistance, mainly to improve the chromium and nickel oxide film The composition, structure and performance degradation, and the higher nickel content the more harmful, mainly because of steel grain boundaries due to a million low melting point nickel sulfide.
6, chromium effects on austenitic stainless steel?
A: The effect of chromium: chromium austenitic stainless steel is the most important alloying element in austenitic stainless steel and corrosion resistance of stainless steel was mainly due to the role will be quality, the chromium passivation of steel and to promote to maintain the stability of passive steel results. ○ 1 Cr impact on the organization: in austenitic stainless steel, chromium is a strong body formation and stability of the elements iron, reduce austenite, with the increase in steel content, Albright stainless steel body, there may be ferrite (δ) organizations, research shows that Cr-Ni austenitic stainless steel, when the carbon content of 0.1%, chromium content of 18%, in order to obtain a stable single austenite, the required minimum nickel content of about 8%, on this point, the type commonly used in 18Cr-8Ni chrome-nickel austenitic stainless steel is chromium, nickel ratio of the most appropriate one.
With austenitic stainless steel, with the increase of chromium content, some intermetallic phases (such as δ-phase) formation tendency increased when the steel contains molybdenum, chromium will increase with Han Liang Xiang Deng also the formation of χ, as previously above, σ, χ phase precipitation is not only a significant reduction in plasticity and toughness, and in some conditions, also reduce the steel corrosion resistance, austenitic stainless steel in the chromium content of martensite could turn hydrocarbon temperature increase (Ms ) decreased, thereby enhancing the stability of the austenitic matrix. so high chromium (for example, more than 20%) austenitic stainless steel even after the cold and low temperature martensite is also difficult to obtain ..
Chromium is a strong carbide forming elements, is no exception in austenitic stainless steel, austenitic stainless steel in common chromium carbide have Cr23C6; when the steel contains molybdenum or chromium, may also see other carbides of Cr6C they under certain conditions the formation of the performance of the steel will have a major impact. ○ 2 chromium on performance: Generally the main, if maintained in a fully austenitic stainless steel without δ ferrite formation, etc., only increase of chromium content of steel does not significantly affect the mechanical properties of chromium on the properties of austenitic stainless steel is the most corrosion resistance, mainly as follows: chromium improve the oxidation resistance of steel media and acidic chloride media performance; in nickel, and molybdenum and copper compound under the action of chromium steel to improve resistance to a number of reducing medium, 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 the condition of a Sports performance under the stress of austenitic stainless steels .. Sports sensitivity between the most important factor is the carbon content, other elements of the stadium between the main function of crystal depending on the carbide dissolution and precipitation behavior may be in austenitic stainless steel, chrome can increase the solubility of carbon decreases degree of chromium depletion, thus increasing chromium content of austenitic stainless steel intergranular corrosion resistance is useful, chromium is very effective in improving the austenitic stainless steel resistance to pitting corrosion and crevice corrosion of steel in the same time when there is molybdenum or molybdenum and nitrogen exist, large to enhance the effectiveness of chromium that, although the study of molybdenum and crevice corrosion resistance point of stadium capacity for the chrome, then times, N 30 times for the chromium, but the large number of studies, austenitic stainless steel in the absence of chromium or chromium content was low, molybdenum and nitrogen in pitting corrosion resistance and crevice corrosion will lose or not significant.
Austenitic stainless steel of chromium on the corrosion properties of the role, 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 the Cl-and oxygen-containing water medium, high temperature and pressure of water and point corrosion at the origin of stress corrosion conditions, chromium content was increased steel stress corrosion resistant beneficial while, chromium can also prevent the austenitic stainless steel and alloy content increased while the nickel crystal can easily arise between the type tendency to stress corrosion, caustic off (NqOH) stress corrosion, the role of chromium is also useful
Chromium addition to the negative's body have a major impact corrosion resistance of stainless steel, the type of steel can significantly improve the antioxidant, anti-melting salt curing and anti-corrosion properties.
7, Carbon on the impact of austenitic stainless steel?
A: The carbon: carbon in the austenitic stainless steel is strong and stable austenite formation and expansion of austenite elements. The capacity of carbon into austenite is about 30 times that of nickel, carbon is a gap element by solid solution strengthening can significantly improve the strength of austenitic stainless steel. carbon austenitic stainless steel can enhance the high concentration of chloride (eg, boiling 42% MgCl2 solution) in the resistance to stress corrosion performance.
However, austenitic stainless steel, carbon is often seen as harmful elements, mainly stainless steel and corrosion due to use some of the conditions (such as welding or heating by 450 ~ 850 ℃), carbon steels can the formation of high-chromium chromium Cr23C6 carbon compounds resulting in localized type of chromium depleted, the steel corrosion resistance, especially resistance to intergranular corrosion . Therefore, new developments since the 60's chrome-nickel austenitic stainless steel is the carbon content of large less than 0.03% or 0.02% ultra-low carbon type, can know with the lower carbon content of steel reduced susceptibility to intergranular corrosion, when the carbon content of less than 0.02%, with only the most obvious effect of some experimental Pearl also pointed out that Carbon also increases the pitting corrosion of chromium stainless steel sub-tendencies. Because the harmful effects of carbon, not only in the austenitic stainless steel smelting in should be required over and control the carbon content as low as possible, and in the subsequent heat, cold and and heat treatment process is also to prevent the stainless steel surface by carbon, and chromium carbide precipitation-free.
8, stainless steel, the physical properties, mechanical properties and heat resistance?

A: The physical properties of stainless steel
The physical properties of stainless steel and carbon steel comparison of the data, slightly higher than the density of carbon steel of ferrite and martensite stainless steel, and slightly lower than the austenitic stainless steel; resistance rates of carbon steel, ferrite size, martensite-type and Austria Sort Ascending's stainless steel body; linear expansion coefficient of the order are similar to carbon austenitic stainless steel of the highest minimum; carbon steel, ferritic and martensitic stainless steel body magnetic, austenitic stainless steel non-magnetic, but the cold hardening Cheng's body build will have a magnetic phase transition, heat treatment method can be used to eliminate the martensite and the restoration of its non-magnetic.

Compared to austenitic stainless steel and carbon steel, have the following characteristics:
1) high electrical resistivity, about 5 times carbon steel.
2) The large linear expansion coefficient than the carbon steel is 40%, and with increasing temperature, linear expansion coefficient values are correspondingly high.
3) low thermal conductivity, carbon steel is about 1 / 3.
Mechanical properties of stainless steel
Whether stainless steel or heat-resistant steel, austenitic steel of the best properties of both adequate strength as well as excellent hardness is not high plasticity, which is widely used because they are one. Austenitic stainless steel with the most similar to other metallic materials, tensile strength, yield strength and hardness, the decrease with temperature increase; plasticity decreases with temperature decrease. The tensile strength in the temperature range of 15 ~ 80 ° C in growth is more uniform. More important: as the temperature decreased, 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
Heat resistance is high, the existing anti-oxidation or corrosion resistant properties of gases that heat stability, while at high temperatures and adequate strength is double tempered.

 

9, the corrosion resistance of stainless steel?

A: The 304 is a universal stainless steel, it is widely used to produce good overall performance requirements (corrosion resistance and formability) of equipment and parts. 301 301 stainless steel in the deformation shows obvious when the work hardening, is used to require a higher intensity of the various occasions.
302 high carbon content stainless steel is essentially a variant of 304 stainless steel by cold rolling to obtain a higher strength can be.
302B is a high silicon content in stainless steel, it has a high temperature oxidation resistance. Respectively 303 and 303Se containing sulfur and selenium-cutting stainless steel, the main requirements for cutting and surface Guanghao high occasions. 303Se stainless steel is also used for the production of parts needed hot upsetting, because in such conditions, this steel has good hot workability.
304L is a low-carbon 304 stainless steel variant of the occasion for the need for welding. Lower carbon content makes it close to the weld heat affected zone in the to minimize carbide precipitation, and carbide precipitation may result in some environments, stainless steel intergranular corrosion (weld erosion).

304N is a nitrogen-containing stainless steel, add nitrogen to improve the strength of steel.
305 and 384 stainless steel with high nickel, its work hardening rate for demanding cold forming of a variety of occasions.
308 stainless steel for the production of electrodes.
309,310,314 and 330 stainless steel, nickel, chromium content higher than that in order to improve the steel under high temperature oxidation resistance and creep strength. The 30S5 and 310S stainless steel but 309 and 310 variants, which differ only with lower carbon content, in order to make the vicinity of the weld to minimize carbide precipitation. 330 stainless steel has a particularly high resistance to carburization ability and thermal shock resistance.
316 and 317 stainless steel with aluminum, which in the marine environment and the chemical industry point of corrosion resistance far superior to 304 stainless steel. Among them, 316 stainless steel by a variety of low-carbon stainless steel 316L, 316N nitrogen and high-strength stainless steel combined with higher sulfur free cutting stainless steel 316F.
321,347 and 348 respectively of titanium, niobium plus tantalum, niobium stabilized stainless steel, suitable for high temperature components used in welding. 348 is applicable to nuclear power industry, stainless steel, tantalum, and drilling on the amount of cooperation with certain restrictions.
10, stainless steel professional terms Xiangjie?

A: Stainless steel

In layman's terms, that is not easily rust stainless steel, in fact, part of the stainless steel, stainless steel of both, but also acid resistance (corrosion resistance). The stainless steel and corrosion resistance is due to its chromium-rich surface oxide film (passive film) formation. This stainless steel and corrosion resistance is relative. Tests show that the steel in the atmosphere, water and other weak medium and nitric oxide of medium, the corrosion resistance of chromium in steel with increasing of water content, when the chromium content reached a certain percentage, the occurrence of the corrosion resistance of steel mutation, that is not easy from rust to rust, never corrosion to corrosion. Many classification of stainless steel. Room temperature, the organizational structure according to the classification of a martensitic, austenitic, ferritic and duplex stainless steel; by the main chemical ingredient, can basically be divided into chromium stainless steel and chrome-nickel stainless steel two systems; by use of sub- with nitric acid-resistant stainless steel, acid resistant stainless steel, seawater resistant stainless steel, etc., can be divided according to type of corrosion-resistant stainless steel pitting corrosion, stress corrosion-resistant stainless steel, intergranular corrosion resistance of stainless steel, etc.; features classified by function can be divided into non-magnetic stainless steel, free cutting steel, low temperature steel, high strength stainless steel and so on. Because stainless steel has excellent corrosion resistance, formability, compatibility and a wide temperature range series of strength and toughness characteristics, so in heavy industry, light industry, household items and building decoration industry and other industries have wide applications for .
Austenitic stainless steel
At room temperature with austenite stainless steel. Cr steel containing about 18%, Ni 8% ~ 10%, C about 0.1%, with stable austenite. Austenitic chromium-nickel stainless steel including the famous steel and 18Cr-8Ni increase on this basis Cr, Ni contents and add Mo, Cu, Si, Nb, Ti and other elements developed series of high-Cr-Ni steel. Non-magnetic stainless steel and high toughness and ductility, but less strength can not be enhanced through the phase transition so that can only be strengthened by cold working. Such as adding S, Ca, Se, Te and other elements, the cutting of good. In addition to oxidation resistance of such steel acid corrosion medium, the if contains Mo, Cu and other elements also capability sulfuric acid, phosphoric acid and formic acid, acetic acid, urea and other corrosion. Such that if the carbon content of steel less than 0.03% or with Ti, Ni, can significantly improve their resistance to intergranular corrosion. High silicon austenitic stainless steel concentrated nitric acid is willing to have a good corrosion resistance. Because stainless steel is comprehensive and a good overall performance, in all walks of life to get a wide range of applications.
Ferritic stainless steel
Using the state to ferrite-based stainless steel. Chromium content of 11% to 30%, with body-centered cubic crystal structure. Type of steel generally does not contain nickel, sometimes also contains a small amount of Mo, Ti, Nb elements until such steel with large thermal conductivity, expansion coefficient, good oxidation resistance, excellent stress corrosion resistance characteristics, and more tolerant atmosphere for the manufacture of , steam, water and oxidation of acid corrosion of parts. The existence of such poor plasticity of steel after welding and corrosion resistance of plastic such as significantly reduced defects, thus limiting its application.Refining Technology (AOD or VOD) applications enable carbon, nitrogen and other elements greatly reduce the gap, thus making this type of steel was widely used.
Austenitic - ferritic duplex stainless steel
Is austenite and ferrite with about half of all stainless steel. In cases with low C, Cr content 18% ~ 28%, Ni content 3% ~ 10%. Some steel also contains Mo, Cu, Si, Nb, Ti, N and other alloying elements. Both of these austenitic steels and ferritic stainless steel features, compared with the ferrite, plastic, higher toughness, no room temperature brittleness, resistance to intergranular corrosion and welding performance are significantly improved, while maintaining the iron 475 ℃ ferritic stainless steel brittle and high thermal conductivity, with superplasticity and so on. Compared with the austenitic stainless steel, high strength and resistance to intergranular corrosion and chloride stress corrosion resistance significantly increased. Duplex stainless steel has excellent resistance to pitting corrosion, is also a section of nickel stainless steel.
Martensitic stainless steel
Heat treatment can be adjusted by the mechanical properties of stainless steel, simple language, is a class of hardened stainless steel. Typical grades for the Cr13 type, such as 2Cr13, 3Cr13, 4Cr13 so. Pure fire, the higher the hardness of different tempering temperature has a different combination of strength and toughness, mainly used for steam turbine blades, cutlery, surgical instruments. According to differences in chemical composition, martensitic stainless steel can be divided into martensitic chromium steel and two types of martensitic chrome-nickel steel. According to the different organizations and the strengthening mechanism, can be divided into stainless steel, martensitic and semi-austenitic (or semi-martensitic) precipitation hardening stainless steel and maraging stainless steel.
 
11, also with magnetic stainless steel Why?
A: People often think that magnets made of stainless steel, verify the authenticity of its merits and does not absorb non-magnetic, that is good, genuine; absorption are magnetic, then that is a fake fake. In fact, this is an extremely one-sided, not practical to identify the wrong way.
Wide variety of stainless steel at room temperature according to the organizational structure can be divided into several categories:
1. Austenitic: If 304,321,316,310, etc.;
2. Martensite or ferrite body: such as 430,420,410, etc.;
Austenitic type is non-magnetic or weakly magnetic, martensite or ferrite is magnetic.
Often used as a decorative stainless steel tube plate most of the 304 type austenitic material is generally non-magnetic or weakly magnetic in the, but the chemical composition caused by fluctuations in refining or processing conditions may also occur with different magnetic properties, but can not be considered counterfeit or failure, this is why?
Mentioned above is non-magnetic austenitic or weakly magnetic, and martensite or ferrite is magnetic, as Segregation of smelting or improper heat treatment will cause a small amount of martensite in austenitic 304 stainless steel or ferrite tissue. This will be 304 stainless steel with a weak magnetic.
In addition, 304 stainless steel after cold working, organizational structure will be transformed to martensite, the greater the degree of cold deformation, the more martensite transformation, the greater the magnetic properties of steel. Number of strips as a group, the production Φ76 pipe, no significant magnetic induction, the production Φ9.5 tube. Ling bending deformation due to the apparent large number of magnetic induction, the production ratio of square tube rectangular pipe due to large deformation, especially the knuckle part of a more intense magnetic distortion is more evident.
To completely eliminate the causes of magnetic steel 304, can be opened by high temperature solution treatment to restore the stable austenite to eliminate magnetic.
In particular to make is due to the above causes the magnetic 304 stainless steel, stainless steel and other materials, such as 430, the magnetic steel is not completely the same level, meaning that 304 always shows the magnetic properties of weak magnetism.
This tells us that if stainless steel with a weak magnetic or non-magnetic, should be identified as 3-4 or 316 material; if the magnetic and carbon steel, as shown strong magnetic material due to discrimination is not a 304.
We recommend the purchase of stainless steel products should be selected from reputable manufacturers of products, do not get petty, beware fooled.
12, the corrosion resistance of stainless steel?

A: The 304 is a universal stainless steel, it is widely used to produce good overall performance requirements (corrosion resistance and formability) of equipment and parts. 301 stainless steel in the deformation shows obvious when the work hardening, is used to require a higher intensity of the various occasions.
302 high carbon content stainless steel is essentially a variant of 304 stainless steel by cold rolling to obtain a higher strength can be.
302B is a high silicon content in stainless steel, it has a high temperature oxidation resistance.
Respectively 303 and 303Se containing sulfur and selenium-cutting stainless steel, the main requirements for cutting and surface Guanghao high occasions. 303Se stainless steel is also used for the production of parts needed hot upsetting, because in such conditions, this steel has good hot workability.
304L is a low-carbon 304 stainless steel variant of the occasion for the need for welding. Lower carbon content makes it close to the weld heat affected zone in the to minimize carbide precipitation, and carbide precipitation may result in some environments, stainless steel intergranular corrosion (weld erosion).
304N is a nitrogen-containing stainless steel, add nitrogen to improve the strength of steel.
305 and 384 stainless steel with high nickel, its work hardening rate for demanding cold forming of a variety of occasions.

308 stainless steel for the production of electrodes.
309,310,314 and 330 stainless steel, nickel, chromium content higher than that in order to improve the steel under high temperature oxidation resistance and creep strength. The 30S5 and 310S stainless steel but 309 and 310 variants, which differ only with lower carbon content, in order to make the vicinity of the weld to minimize carbide precipitation. 330 stainless steel has a particularly high resistance to carburization ability and thermal shock resistance.
316 and 317 stainless steel with aluminum, which in the marine environment and the chemical industry point of corrosion resistance far superior to 304 stainless steel. Among them, 316 stainless steel by a variety of low-carbon stainless steel 316L, 316N nitrogen and high-strength stainless steel combined with higher sulfur free cutting stainless steel 316F.
321,347 and 348 respectively of titanium, niobium plus tantalum, niobium stabilized stainless steel, suitable for use in welding high temperature components. 348 is applicable to nuclear power industry, stainless steel, tantalum, and drilling on the amount of cooperation with certain restrictions

 
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