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Duplex steels and their types

Alloy for corrosion-resistant iron-based Steel corrosion resistant Steel corrosion resistant heat resistant Steel corrosion resistant heat resistant Steel corrosion resistant, heatresistant and heat-proof Duplex steels and their types Alloy 01Х18Н40М5Г2ТФРЮ (ЭП753У) Alloy 01Х18Н40М5ГБ (ЭП753; ЧС116) Alloy 01Х18Н40М5ГБР (ЭП753Р) Alloy 03KHN28MDT (ЭП516) Alloy 06HN28MDT (ЭИ943) Alloy 06KHN28MT (ЭИ628) Alloy Х33ТМДЮ (ЭК63) Alloy ХН30МДБ (ЭК77) Alloy ХН40Б (ЭП337) Alloy ХН40М5Т2ГЮБР (ЭК173) Alloy ХН40МДБ (ЭП937) Alloy ХН40МДТЮ (ЭП543У) Alloy ХН46Б (ЭП350; 0Х20Н46Б) Steel 015Х16Н15М3 Steel 02Х17Н14М3 Steel 02Х18Н11 Steel 02Х21Н21М4Г2Б (ЗИ69) Steel 02Х21Н25М5ДБ (ЭК5) Steel 02Х25Н22АМ2 (ЧС108) Steel 03Х11Н10М2Т2 (ЭП853) Steel 03Х12К10М6Н4Т (ЭП927) Steel 03Х12Н10МТР (ЭП810; VNS-25) Steel 03Х13АГ19 (ЧС36) Steel 03Х15Н35Г7М6Б (ЭП855) Steel 03KH16N15M3 (ЭИ844) Steel 03Х17АН9 (ЭК177) Steel 03Х17Н14М2 Steel 03Х18Н11 (000Х18Н11) Steel 03Х18Н12 (000Х18Н12) Steel 03Х18Н12Т (000Х18Н12Т) Steel 03Х20Н45М5Б (ЧС32; 03ХН45МБ) Steel 03KH21N21M4GB (ЗИ35) Steel 03Х21Н25М5ДБ Steel 03KH22N6M2 (ЗИ67) Steel 03Х23Н6 (ЗИ68) Steel 04X17H10M2 Steel 04Х15СТ Steel 04KH17T Steel 04KH18N10 (ЭИ842) Steel 04Х19МАФТ Steel 04Х25Н5М2 (ДИ62) Steel 04Х32Н8 (ЭП535) Steel 05Х12Н2К3М2АФ (ANS-40) Steel 05Х12Н9М2С3 (ЭП821) Steel 05Х20Н15АГ6 (ЧС109) Steel 05ХГБ Steel 06Х12Н3Д (08Х12Н3Д) Steel 06Х12НЗД Steel 06Х13Н4ДМ Steel 06Х14Н6Д2МБТ (ЭП817) Steel 06Х15Н4ДМ Steel 06KH18N11 (ЭИ684) Steel 07KH16N6 Steel 07Х15Н7ЮМ2 (ЭП35; CH-4; Х15Н8М2Ю) Steel 07KH16N4B Steel 07KH16N6 (ЭП288; SN-2A; Х16Н6) Steel 07Х18Н10Р (ЭП287) Steel 07KH21G7AN5 (ЭП222) Steel 08Х10Н16Т2 (0Х10Н16Т2) Steel 08KH10N20T2 (0Х10Н20Т2) Steel 08KH17N13M2T (0Х17Н13М2Т; ЭИ448) Steel 08KH17N15M3T (ЭИ580) Steel 08KH17N5M3 (ЭИ925) Steel 08KH17N6T (DI-21) Steel 08KH18G8N2T (KO-3) Steel 08KH18N12B (ЭИ402) Steel 08KH18N12T (0Х18Н12Т) Steel 08Х18Н4Г11АФ (HH-3F) Steel 08Х18Н5Г11БАФ (NN-3БФ) Steel 08Х18Н5Г12АБ (NN-3B) Steel 08Х18Н7Г10АМ3 (08Х18Н7Г10АМ3С2) Steel 08kh18tch (DI-77) Steel 08Х20Н4АГ10 (NN-3) Steel 08Х21Г11АН6 (APA-53) Steel 08KH22N6T (ЭП53) Steel 08ХГСДП Steel 09KH15N8JU1 (09H15N8YU; ЭИ904) Steel 09KH16N4B (ЭП56; 1Х16Н4Б) Steel 09KH17N7JU (ЭИ973) Steel 09KH17N7JU1 (0Х17Н7Ю1) Steel 10KH14AG15 (DI-13) Steel 10Х14Г14Н3 (DI-6) Steel 10X17H13M2T (ЭИ448) Steel 10H17N13M3T (ЭИ432) Steel 10Х17Н5М2 (ЭП405) Steel 10Х18Н5Г9АС4 (ЭП492; ANS-3) Steel 10Х32Н4Д (ЭП529) Steel 11Х13Н3 Steel 12Х13Г12АС2Н2 (ДИ50) Steel 12H17G9AN4 (ЭИ878) Steel 12Х17Н8Г2С2МФ (ЗИ126) Steel 12H18N10E (ЭП47) Steel 12Х18Н13АМ3 (ЭП878) Steel 12H21N5T (ЭИ811; 1Х21Н5Т) Steel 13Х18Н10Г3С2М2 (ЗИ98) Steel 15Х17АГ14 (ЭП213) Steel 15KH18N12S4TJU (ЭИ654; 2Х18Н12С4ТЮ) Steel 18Х13Н3 Steel 20KH13N4G9 (ЭИ100) Steel 20KH17N2 (2Х17Н2) Steel 25KH13N2 (ЭИ474) Steel 25Х17Н2 (ЭП407) Steel 25Х17Н2Б Steel 26Х14Н2 (ЭП208) Steel 30CH13 (upon a time 3x13) Steel 40H13 (4Х13) Steel 65h13 Steel 95Х13М3К3Б2Ф (ЭП766) Steel 95X18 (ЭИ229) Steel Х17Н14М2Т Steel Х17Н14М3Т Steel 015Н18К13М5ТЮ (ЭП948; ЧС35) Steel 015Н18М4ТЮ (ЭП989; ЧС5У) Steel 015Х18Н15Р09 (ЭП166А) Steel 015Х18Н15Р13 (ЭП166Б) Steel 015Х18Н15Р17 (ЭП167А) Steel 015Х18Н15Р22 (ЭП167Б) Steel 015Х18Н15Р26 (ЭП168А) Steel 015Х18Н15Р30 (ЭП168Б) Steel 01Н18К9М5Т (ЭП637У) Steel 02Н15К10М5Ф5 Steel 02Н18М3К3Т (ЭК165; ЧС101) Steel 02Х8Н22С6 (ЭП794) Steel 03Н10Х12Д2Т Steel 03Н14Х5М3Т (ЭП777) Steel 03Н14Х5М3ТЮ (OMS-2) Steel 03Н15К10М5Ф5 (ЭК169) Steel 03Н17К10В10МТ (ЭП836) Steel 03Н18К1М3ТЮ (ЗИ80) Steel 03Н18К8М3ТЮ (ЗИ25) Steel 03Н18К9М5ТЮ (its predecessor, the čs4) Steel 03Н18М3ТЮ (CHS5) Steel 03Н18М4ТЮ (ЧС25) Steel 03Х11Н10М2Т (ЭП678; ANS-17) Steel 03Х11Н10М2Т1 (ЭП679) Steel 03Х12Н8К5М2ТЮ (ЗИ90) Steel 03Х12Н8МТЮ (ЗИ37) Steel 03Х13Н5М5К9 (VNL-6) Steel 03KH17N14M3 (ЗИ66) Steel 04Х16Н11М3Т (ДИ95) Steel 05Х12Н2М Steel 05Х12Н5К14М5ТВ (ЭП695) Steel 06Х13Н7Д2 (ЭП898) Steel 06Х15Н6МВФБ (ВНС16) Steel 06Х16Н15М2Г2ТФР (ЧС68) Steel 06Х16Н15М3БР (ЭП172) Steel 07Х12НМБФ (ЭП609) Steel 07Х12НМФБ (ЧС80) Steel 07Х15Н30В5М2 (ЧС81) Steel 07Х25Н16АГ6Ф (ЭП750) Steel 08KH13 (ЭИ496) Steel 08Х14Н2К3МФБ (ЭК93; ANS-51) Steel 08Х16Н11М3 Steel 08Х19Н12ТФ Steel 08Х20Н12АБФ Steel 09Х17Н (ЧС130) Steel 09Х18Н9 Steel 10Х12Н20Т2 (ЭП452) Steel 10Х12Н3М2БФ Steel 10KH18N10T (ЭП502) Steel 10Х18Н9 Steel 10Х20Н33Б Steel 10Х25Н6АТМФ Steel 11Х17Н Steel 12Х12М1БФР (ЭП450) Steel 12KH18N9 (Х18Н9) Steel 13Х16Н3М2АФ (ВНС57) Steel 14KH17N2 (ЭИ268) Steel 14Х20Н25В5МБ (lit) Steel 15Х16Н2АМ (ЭП479) Steel 16Х12В2ФТаР (EK181) Steel 17H18N9 (2Х18Н9) Steel 20Х12НМВБФАР (CHS139) Steel 20X13 (02Х13) Steel 20Х13Н2ДМЮФ (ДИ96) Steel 23Х15Н5АМ3 (18Х15Н6АМ3; VNS-9) Steel 30Х23Н7С Steel 32Х13Н6К3М2БДЛТ (ANS-32; СЭС1) Steel 35Х24Н24Б Steel 45Х25Н20С Steel 45Х25Н20С2 Steel 45Х25Н35БС Steel 45Х28Н49В5С Steel 4Х13Н6ЛВФ (ЭП354) Steel 50Х15МФАСч Steel 50Х20Н35С2Б Steel 50Х25Н35В5К15С Steel 50Х25Н35С2Б Steel 80Х20НС (ЭП992) Steel 9Х13Н6ЛК4 (ЭИ928) Steel CHS 116-ID (ЭП753У-ID) Steel 015Х18М2Б (ЭП882) Steel 01Х18 (ЧС86) Steel 01Х18М2Т (ЧС77) Steel 01Х18Т (ЧС74) Steel 01Х1ЗМБСч (ЭП933) Steel 01Х25М2Т (ЧС78) Steel 01Х25Т (ЧС75) Steel 01Х25ТБЮ (ЧС76; 01Х25ТБ) Steel 03Х11Н8М2Ф (ДИ52) Steel 03Х17Н8Г5МФАБ (APA-31) Steel 03KH18N10T (03Х18Н10; 18CR10NITI) Steel 03Х20Ю3НТБ (KO-4) Steel 05KH18N10T (0Х18Н10Т) Steel 06Х16Н2К5ФМБ (ЭП875; ANS-26) Steel 06Х18Г9Н5АБ (06Х18Г5Н5АБ; ЧС51) Steel 06KH18N10T (06Х18Н10) Steel 06Х20Н14С2 Steel 08KH17T (ЭИ645) Steel 08H18N10 (ЭИ119) Steel 08KH18N10T (ЭИ914) Steel 08KH18T1 (0Х18Т1) Steel 08KH20N14S2 (ЭИ732) Steel 09KH18N10T (1Х18Н10Т) Steel 10Х13Г18Д (DI-61; 12Х13Г18Д) Steel 10Х15Н27Т3МР (ЭП700) Steel 12X17 (X17) Steel 12Х20Н14С2 (ЭИ732) Steel 13Х13С2М2 (ЭИ852) Steel 15KH25T (ЭИ439) Steel 15KH28 (ЭИ349) Steel 20KH20N14S2 (ЭИ211) Steel 4Х18Н2М (ЭП378) Steel 015Х14Н19С6Б (ЧС110) Steel 015Х20Н25Г2Б (ЭП754) Steel 02Х24Н6АМ3 (ДИ91) Steel 03Н18К9М5Т (ЭП637; МС200) Steel 03KH16N15M3B (026Х16Н15М3Б; ЭИ844Б) Steel 03Х18Н9Т (Х18Н9Т) Steel 03Х19Н15Г6М2АВ2 (ЧС39) Steel 03Х21Н32М3Б (ЭП864; ЧС33) Steel 03Х24Н6АМ3 (ЗИ130) Steel 03Х9К14Н6М3Д (ЭП921; 03Х9К14Н6М3ДФ) Steel 04Х11Н9М2Д2 (ЭП832; 04Х11Н9М2Д2ТЮ) Steel 04Х13Н4АГ20 (ЧС52) Steel 04Х14К13Н4М3ТВ (ЭП767) Steel 05Х15Н9Г6АМ (ЧС31) Steel 05Х21Н12Г2БРч (ДИ94) Steel 07Х13АГ20 (ЧС46) Steel 08Х14Ф Steel 08Х20Н5АГ12МФ (ДИ8) Steel 08KH21N6M2T (ЭП54) 10Х12Н3М2ФА steel (CSD-M) Steel 10Х12НД (0Х12НД) Steel 10Х13Г12БС2Н2Д2 (ДИ59) Steel 10Х18Г14АН4 (ЭП197; Х18Г14АН4) Steel 10Х32Н8 (ЭП263; Х32Н8) Steel 10Х9МФБ (ДИ82) Steel 12Х11В2МФ (ЭИ756) Steel 12H13 (1Х13) Steel 12KH18N10T (18CR10NITI) Steel 12Х18Н12Т (Х18Н12Т) Steel 12Х18Н9СМР (ЭП414; Х18Н9СМР) Steel 12X18H9T (Х18Н9Т) Steel 16Х20К6Н2МВФ (ЭП768; VNS-22) Steel 19Х20Н4АМ3Д2С (ЭК7) Steel 90Г29Ю9ВБМ (ДИ38; 90Г29Ю9ВМБФ; ДИ38Ф)

Description

Duplex steel

It is important to note that this steel is called two-phase because it has austenitic and ferritic phases.

Duplex stainless steel is quite popular. Recently, it has gained even more popularity. Many manufacturers are engaged in its production. This is preceded by certain reasons:

  • increased degree of strength, which allows to reduce the weight of manufactured products;
  • resistance to corrosion processes, especially cracking.

Duplex conferences are held approximately every two or three years. They present interesting articles with deep technical content. Today, duplex steel is actively promoted in the market for goods and services. New brands launching this product regularly appear on the market.

Despite the high share of optimism, according to statistics, this product is about one to three percent of the market.

General information

The idea of creating a product first appeared at the beginning of the last century. The first melting was carried out in the 30s. A noticeable increase in the share of material use has been noticeable in recent years. This is due to the improvement of production processes. Previously, the content of nitrogen in production was regulated.

Austenitic (AISI 304), ferritic (AISI 430) stainless steel are easy to manufacture. Easy to handle. They consist of one phase — austenite or ferrite. They are widely used in various fields. Each type has its own technical disadvantages:

1. Austenitic. They are characterized by low strength characteristics. The approximate yield point is 0.2% immediately after austenitizing 200 MPa. The product has a low resistance to stress corrosion cracking.
2. Ferritic. The following disadvantages are characteristic: the minimum strength, which is slightly higher than that of the previous type. The approximate yield point — 0.2% is 250 MPa. The product does not weld well at large thicknesses. Differs in fragility when the temperature drops.

Due to the high content of nickel in the composition, austenitic stainless steel is expensive. This makes the product less in demand.

The idea of creating the product under consideration is to select a suitable chemical composition, which forms a similar volume of ferrite, austenite. The phase composition gives such positive qualities:

1. Strength qualities. The approximate yield point is 0.2%. Manufacturers offer the product after austenitization — 400 — 450 MPa. This minimizes the cross-section of the elements. The weight of the product becomes less. Makes sense in areas like:

  • pressure vessels, steel tanks;
  • bridges.

2. The ability to weld large thicknesses.
3. High degree of impact strength. Higher than ferritic stainless steel. It is especially clearly seen at low temperature conditions: — 50 degrees Celsius. It can withstand up to — 80 degrees Celsius.
4. Resistance to stress corrosion cracking. Austenitic stainless steel is susceptible to this phenomenon. Modern materials make it possible to resist the process. The advantage is important in the production of such structures:

  • tanks designed for heating hot water;
  • brewing tanks;
  • concentration plants;
  • pool frames.

How is the balance of duplex stainless steels achieved?

You can understand how such a product is obtained by comparing the composition of two types: austenitic — AISI 304 and ferritic — AISI 430 stainless.

The main components of materials can be divided into ferritizing, austenitizing. Each of them helps to form a certain structure.

Ferritizing elements are Cr (chromium), Si (silicon), Mo (molybdenum), W (tungsten), Ti (titanium), Nb (niobium).

Austenitizing components: C (carbon), Ni (nickel), Mn (manganese), N (nitrogen), Cu (copper).

Structure Brand EN designation Mo Ni Cr N S P Mn Si C
Austenitic 304 1.4301 - 8.0−10.5 17.5−19.5 0.11 0.015 0.045 2.00 1.00 0.07
Ferritic 430 1.4016 - - 16.0−18.0 - 0.015 0.040 1.00 1.00 0.08

The AISI 430 brand has ferritizing elements. Its structure is ferritic. The AISI 304 grade is distinguished by its austenitic structure due to the presence of nickel in the composition in the amount of eight percent. To obtain a duplex with the presence of each phase of about fifty percent, a balance of austenitizing and ferritizing components is needed. This is the main reason why the concentration of nickel in such stainless steel is much lower than in austenitic.

Brand EN / UNS number A type Approximate content
Cr Ni Mo N Mn W Cu
Ferrinox255 /
Uranus 2507Cu
1.4507 /
S32520 /
S32550
Super 25 6.5 3.5 0.25 - - 1.5
Zeron 100 1.4501 /
S32760
Super 25 7 3.2 0.25 - 0.7 0.7
2507 1.4410 /
S32750
Super 25 7 4 0.27 - - -
2205 1.4462 /
S31803 /
S32205
Standard 22 5.7 3.1 0.17 - - -
2304 1.4362 /
S32304
Low alloyed 23 4.8 0.3 0.10 - - -
RDN 903 1.4482 /
S32001
Low alloyed 20 1.8 0.2 0.11 4.2 - -
DX 2202 1.4062 / S32202 Low alloyed 23 2.5 0.3 0.2 1.5 - -
LDX 2101 1.4162 /
S32101
Low alloyed 21.5 1.5 0.3 0.22 five - -

Some brands that have recently appeared on the modern market use a compound of manganese, nitrogen to significantly minimize the presence of nickel. This has a beneficial effect on the formation of the cost of production.

To this day, the technology for the production of such stainless steel is gradually gaining momentum. Each manufacturer offers its own brand. There are a lot of brands that are engaged in the manufacture and sale of duplex steels. A little later it will be possible to see how leading manufacturers enter the market.

Duplex corrosion resistance

Due to the wide variety of materials, when identifying corrosion resistance, they are brought together with austenitic, ferritic grades. Corrosion resistance is not the same measure. The Pitting Resistance Equivalent (PREN) can be used to classify manufacturers.

Brand EN / UNS number A type Indicative PREN
6% Mo 1.4547 /
S31254
Austenitic 44
2507 1.4410 /
S32750
Duplex 43
Ferrinox 255 /
Uranus 2507Cu
1.4507 /
S32520 /
S32550
Duplex 41
Zeron 100 1.4501 /
S32760
Duplex 41
2205 1.4462 /
S31803 /
S32205
Duplex 35
904L 1.4539 /
N08904
Austenitic 34
DX2202 1.4062 / S32202 Duplex 27
2304 1.4362 /
S32304
Duplex 26
2101 LDX 1.4162 /
S32101
Duplex 26
316L 2.5 Mo 1.4435 Austenitic 26
444 1.4521 /
S44400
Ferritic 24
316 1.4401 /
S31600
Austenitic 24
RDN 903 1.4482 /
S32001
Duplex 22
441 1.4509 /
S43932
Ferritic nineteen
304 1.4301 /
S30400
Austenitic nineteen
430 1.4016 /
S43000
Ferritic sixteen

When choosing the type of steel, you need to pay attention to how suitable it is for operation in a particular corrosive environment.

Stress corrosion cracking

SCC is a type of corrosion that appears when exposed to a whole range of external factors:

  • corrosive environment;
  • tensile stress;
  • high temperature conditions, up to +50 degrees Celsius.

Duplex steels such as austenitic steels such as AISI 304 and AISI 316 are susceptible to stress corrosion cracking. The following materials are more resistant to cracking:

  • ferritic;
  • duplex steels;
  • austenitic steels characterized by a high concentration of nickel in the composition.

Resistance to stress corrosion cracking makes it possible to use duplex in many types of processes carried out at high temperature conditions:

  • used for the manufacture of water heating structures;
  • used for the production of tanks for brewing beer;
  • used for the manufacture of desalination plants.

Steel pool frame structures are also known for their tendency to stress corrosion cracking. The use of simple austenitic stainless steels for welding is strictly prohibited. Suitable for this procedure are austenitic steels known for their high nickel content. Super Duplex Steel is an excellent alternative to this material.

Reasons behind the slow ubiquity of duplex steels

High strength, a wide range of values of resistance to corrosion phenomena, an average degree of weldability — all this should increase the level of production of this material. But, you need to understand that such steels have certain disadvantages. They prevent duplex steels from fully covering the market for these products.

The increased degree of strength is considered one of the disadvantages when it comes to the manufacturability of processing raw materials by pressure. This indicates a lower deformation capability than austenitic steels. For this reason, the material is unsuitable for the manufacture of products that require a high degree of plasticity. When the ability for this type of deformation is at an acceptable level, sufficient force is required to give the raw material a suitable shape, for example, when bending pipes. There is one exception to the rule regarding unsatisfactory cutting machinability: LDX 2101 from Outokumpu.

Duplex_Stainless_Steels1.jpg

The process of melting duplex steels is rather complicated and laborious. If the production technology is violated, more unwanted phases may appear.

The formation of the sigma phase is noted when there is a deficit in the cooling rate during production and welding. If a large number of alloying elements prevail in steel, then the probability of the formation of this phase increases. In this case, the most vulnerable are super duplex steels.

Typically, 475-degree brittleness is noted during the formation of a phase called α '(alpha bar). This temperature regime is dangerous. It should be noted that brittleness can appear even at temperatures of 300 degrees Celsius. This provokes the appearance of certain restrictions on the maximum temperature for using this raw material. Often this restriction further narrows the range of possible uses.

It is important to note that even with the minimum permissible temperature regime for the use of such a material, there are certain restrictions. Duplex steels have a brittle-tough transition when tested for impact resistance. The permissible temperature regime for testing products that are used for the manufacture of structures for offshore oil and gas production is 46 degrees Celsius.

Overview of the main properties of the duplex

They are as follows:

1. The strength of the material is several times greater than that of other types.
2. It has an impressive range of corrosion resistance values. This makes it possible to choose the right brand depending on the purpose.
3. High impact strength is up to -80 degrees Celsius. This significantly limits the scope of use in cryogenic environments.
4. High degree of resistance to stress corrosion cracking.
5. Excellent weldability of large sections.
6. The appearance of some difficulties in machining, stamping.
7. The maximum application temperature of the material in question is limited to 300 degrees Celsius.

The price of this material is affordable, so it can be bought in our country at a good price. It has many benefits. For example, the cost of two-phase raw materials is significantly lower than the price of other stainless metals. The strength characteristics are significantly higher than that of the AISI 300 class product. This makes it possible to use much less raw materials for the same type of equipment.

Duplex steel is actively used in the automotive industry. Many businesses use this material. This allows you to create a model of transport that meets the basic requirements of protection, without increasing the weight of the product. With the use of modern technologies and materials, as a rule, the weight of a car becomes about a third more. That is why it is worth using two-phase steels to significantly reduce vehicle weight. At the same time, the security problem is being addressed. Duplex allows the production of vehicles that meet all basic safety standards. At the same time, no increase in the price of the final product due to the use of this type of raw material occurs.

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