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List of Stackless Steel Classification by Type Stackless Steel, Type, Classification

The following content can be deep everyone&# 039; Understanding of the classification of stainless steel and facilitate selection

Currently, the commonly used stainless steel are 304 and 316, which are cheep in price and high in price

Able to choose different types of stainless steel according to their respective needs

200 Series - Chromium Nickel Manganese Austenitic Stainless Steel

300 Series - Chromium Nickel Austenitic Stainless Steel

Type 301- Good conductivity, used for forming products It can also be quickly hardened through mechanical processing Good weldability The wear resistance and fatigue strength are better than 304 stainless steel

Type 302- has the same corrosion resistance as 304, but has better strength due to its relatively high carbon content

Type 303- By adding a small amount of sulfur and phophorus, it is easier to machine than 304

Type 304- Universal type; Namely 18/8 stainless steel The GB brand is 0Cr18Ni9

Type 309- has better temperature resistance than 304

Type 316- The second most widely used steel grade after 304, mainly used in the food industry and substantial equipment, with the addition of molybdenum to achieve a special corrosion resistant structure Due to its better resistance to chloride corrosion compared to 304, it is also used as a "marine steel" SS316 is generally used for nuclear fuel recovery equipment Grade 18/10 stainless steel is generally suitable for this application level

Type 321- Except for reducing the risk of welding seam corrosion due to the addition of titanium element, other functions are similar to 304

400 Series - Ferritic and Martensitic Stainless Steel

Type 408- Good heat resistance, weak corrosion resistance, 11% Cr, 8% Ni

Type 409- The cherry type (British and American), commonly used for automotive exhaust pipes, is ferritic stainless steel (chromium steel)

Type 410 martensite (high strength chromium steel), with good wear resistance and poor corrosion resistance

Type 416- Added sur to improve data processing capabilities

Type 420- "cutting tool grade" martensitic steel, similar to the earliest stainless steel, Brinell high chromium steel It is also used as a surgical tool and can be made very much

Type 430- Ferritic stainless steel, for decorative purposes, such as in automotive accessories Excellent capability, but poor temperature and corrosion resistance

Type 440- High strength cutting tool steel, slightly higher in carbon content, can achieve high yield strength after appropriate heat treatment, and has a hardness of up to 58HRC, making it one of the hardened stainless steel The most common example of use is the&# 039; Razor blade&# 039 There are three common types: 440A, 440B, 440C, and other types include 440F (easy to process) (WeChat official account: elevator)

500 series - heat resistant chromium alloy steel

600 Series - Martensitic Deposit Hardening Stainless Steel

Type 630- The most commonly used type of deposit hardened stainless steel, also known as 17-4; 17% Cr, 4% Ni

Classification, main components, and comparison of mechanical process functions of stainless steel

Stainless steel can be divided into chromium stainless steel, chromium nickel stainless steel, chromium manganese nitrogen stainless steel, chromium nickel molybdenum stainless steel, as well as ultra low carbon stainless steel, high molybdenum stainless steel, high purity stainless steel, etc. according to its main chemical composition; Classified according to the functional characteristics and uses of steel, such as nitrate acid resident (nitrate acid grade) stainless steel, sulfuric acid resident stainless steel, Pitting resident stainless steel, stress resident stainless steel, high strength stainless steel, etc

Classified according to the functional characteristics of steel, such as low temperature stainless steel, non magnetic stainless steel, easy cutting stainless steel, superplastic stainless steel, etc. Generally classified by metallic arrangement According to the metallurgical arrangement, it is classified as: ferritic (F) type maintainless steel, martensitic (M) type maintainless steel, austenitic (A) type maintainless steel, austenitic ferrite (A-F) type duplex maintainless steel, austenitic martensitic (A-M) type duplex maintainless steel, and disposition hardening (PH) type maintainless steel

The following are the specific classifications, main components, and mechanical process functions of stainless steel:

Classification approximate composition (%) Quenching resistance, correction resistance, workability, weldability, magnetic properties

C Cr Ni

Ferrite system below 0.35 16-27- no good, still good, still available

Markov system below 1.20, 11-15- Self Hardening Cocoa not available

Under 0.25 and above 16 and above 7 in the Aoshi system, no optimization, no optimization, no optimization

The above classification is only based on the arrangement of the steel matrix In addition to the three fundamental types mentioned above, the arrangement of stainless steel used in industry also includes transition type duplex stainless steel such as martensite ferrite, austenitic ferrite, austenitic martensite, and disposition hardening stainless steel with martensite carriage arrangement

2-1. Ferritic steel

Low carbon chromium stainless steel with a chromium content greater than 14%, chromium stainless steel with a chromium content of 27%, and stainless steel with elements such as molybdenum, titanium, niobium, silicon, aluminum, tungsten, and advanced added to the above composition The elements that form ferrite in the chemical composition are independently dominant, and the matrix arrangement is ferrite This type of steel is arranged as ferrite under quenching (solid solution) conditions, while a small amount of carbides and intermetallic compounds can be seen in the arrangement of anchoring and aging conditions. There are Crl7, Cr17Mo2Ti, Cr25, Cr25Mo3Ti, Cr28, etc. that belong to this category. Ferritic stainless steel, due to its high chromium content, has good corrosion resistance and oxidation resistance, but poor mechanical and process performance. It is often used in acid resistant structures with low stress and as an oxidation resistant steel.

2. Ferritic martensitic steel

This type of steel is y+a at high temperatures (or δ） In two-phase conditions, there is a y-M change during rapid cooling, and the ferrite is still retained. It is arranged as martensite and ferrite at room temperature. Due to differences in composition and heating temperature, the amount of ferrite in the arrangement can vary from a few percent to several tens. 0Crl3 steel, lCrl3 steel, 2Cr13 steel with upper chromium limit and lower carbon limit, Cr17Ni2 steel, Cr17wn4 steel, as well as many steel grades such as Cr11MoV, Cr12WMoV, Crl2W4MoV, 18Crl2WMoVNb, which have been developed on the basis of ICrl3 steel, are all in this category.

Ferritic martensitic steel can partially undergo quenching strengthening, thus achieving high mechanical performance. But their mechanical and technological functions are largely influenced by the content and distribution of ferrite in the arrangement. This type of steel belongs to two series, 12-14% and 15-18%, based on the chromium content in its composition. The former has the ability to resist atmospheric and weakly corrosive media, and has excellent shock absorption and small linear expansion coefficient; The corrosion resistance of the latter is equivalent to that of ferritic acid resistant steel with the same chromium content, but to some extent, it also retains certain defects of high chromium ferritic steel.

2-3. Martensitic steel

This type of steel is in the y-phase zone at normal quenching temperature, but their y-phase is only stable at high temperatures, and the M-point is generally around 3OO ℃, so it changes to martensite during cooling. This type of steel includes 2Cr13, 2Cr13Ni2,3Cr13, as well as some modified 12% chromium heat resistant steel, such as 13Cr14NiWVBA, Cr11Ni2MoWVB steel, etc. The mechanical properties, corrosion resistance, process and physical properties of martensitic stainless steel (WeChat official account: elevator) are all similar to those of ferritic martensitic stainless steel containing 12-14% chromium. Due to the absence of free ferrite in the arrangement, the mechanical performance is higher than that of the aforementioned steel, but the sensitivity to overheating during heat treatment is lower.

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2-4. Martensitic carbide steel

The carbon content at the eutectoid point of Fe-C alloy is 0.83%. In stainless steel, the S point shifts to the left due to chromium. Steels containing 12% chromium and more than 0.4% carbon (Figure 11-3), as well as steels containing 18% chromium and more than 0.3% carbon (Figure B) 3), belong to hypereutectoid steels. This type of steel is heated at normal quenching temperature, and secondary carbides cannot be completely dissolved in austenite, so the arrangement after quenching is composed of martensite and carbides.

There are not many stainless steel grades belonging to this category, but some stainless steels with high carbon content, such as 4Crl3, 9Cr18, 9Crl8MoV, 9Crl7MoVCo steel, etc. 3Crl3 steel with upper carbon content may undergo quenching at lower temperatures, which may also lead to such arrangements. Due to its high carbon content, although the three steel grades mentioned above, such as 9Cr18, contain a significant amount of chromium, their corrosion resistance is only equivalent to stainless steel containing 12-14% germanium. The main use of this type of steel is for parts that require high hardness and wear resistance, such as cutting tools, bearings, springs, and medical devices.

2-5. Austenitic steel

This type of steel contains many elements that expand the y zone and do not disturb austenite, which are all in the y phase at high temperatures. When cooling, due to the Ms point being below room temperature, it has an austenite arrangement at room temperature. Chromium nickel stainless steels such as 18-8, 18-12, 25-20, and 20-25Mo, as well as low nickel stainless steels such as Cr18Mnl0Ni5, Cr13Ni4Mn9, Cr17Ni4Mn9N, Cr14Ni3Mnl4Ti steel that replace some nickel with manganese and add nitrogen, all belong to this category.

Austenitic stainless steel has many advantages mentioned earlier, although its mechanical performance is relatively low, and it cannot be strengthened by heat treatment like ferritic stainless steel. However, it can be deformed through cold work to improve its strength through work hardening effect. The defects of this type of steel are sensitive to intergranular corrosion and stress corrosion, and require appropriate alloying agents and process methods to eliminate them.

2-6. Austenitic Ferritic Steel

This type of steel, due to the expansion of the y zone and the lack of disordered austenite elements, is not sufficient to have a pure austenite arrangement at room temperature or very high temperatures. Therefore, it is in an austenite ferrite duplex state, and its ferrite content can also vary over a large range due to differences in composition and heating temperature.

There are many types of stainless steel belonging to this category, such as low-carbon 18-8 chromium nickel steel, 18-8 chromium nickel steel with titanium, niobium, and molybdenum, especially ferrite can be seen in the arrangement of casting steel. In addition, chromium manganese stainless steel (such as Cr17Mnll) containing more than 14-15% chromium but less than 0.2% carbon, as well as most chromium manganese nitrogen stainless steel currently studied and used. Compared with pure austenitic stainless steel, this type of steel has many benefits, such as higher yield strength, higher ability to resist intergranular corrosion, lower sensitivity to stress corrosion, less tendency to produce hot cracks during welding, and good casting activity. The defects are poor pressure processing performance, high tendency for pitting corrosion, easy occurrence of C-phase brittleness, and weak magnetism under strong magnetic field effects. All these benefits and defects stem from the ferrite in the arrangement.

2-7. Austenitic Bowl Martensitic Steel

The Ms point of this type of steel is lower than room temperature, and the solution treatment will be arranged for austenite in the future, making it easy to form and weld. There are generally two processes available to induce martensitic changes. Firstly, after solid solution treatment, after heating at 700-800 degrees Celsius, the austenite will change to a stable state due to the separation of chromium carbide. The Ms point will rise above room temperature and change to martensite upon cooling; The second is to directly cool the solid solution treatment to the point between Ms and Mf in the future, causing austenite to change into martensite. The latter method (WeChat official account: elevator) can achieve high corrosion resistance, but the interval from solid solution treatment to deep cooling should not be too long, otherwise the strengthening effect of deep cooling will be reduced due to the aging effect of austenite. After the above treatment, the steel will undergo further aging at 400-500 degrees to further strengthen the intermetallic compounds separated. Typical steel grades for this type of steel include 17Cr-7Ni-A1, 15Cr-9Ni-A1, 17Cr-5Ni-Mo, 15Cr-8Ni-Mo-A1, and so on. This type of steel is also known as austenitic martensitic aging stainless steel, and due to the fact that in addition to austenite and martensite, there are different numbers of ferrite in the arrangement of these steels, it is also known as semi austenitic deposition hardening stainless steel.

This type of steel is a new type of stainless steel developed and used in the late 1950s. Its overall characteristics are high strength (C can reach 100-150) and good thermal strength. However, due to its low chromium content and the separation of chromium carbide during heat treatment, its corrosion resistance is lower than that of standard austenitic stainless steel. It can also be said that the high strength of this type of steel is achieved at the expense of some corrosion resistance and other functions (such as non magnetic). Currently, this type of steel is mainly used in the aviation industry and rocket missile production, but it is not widely used in general mechanical manufacturing, and they are also classified as a series of ultra-high strength steel.

Article source: Stainless steel faucet manufacturer http://winseo.cn/

Introduction to Stainless Steel Model Classification