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Duplex steels and their types

Corrosion-resistant iron-nickel alloy Corrosion-resistant steel Corrosion-resistant heat-resistant steel Corrosion-resistant heat-resistant steel Corrosion-resistant, heat-resistant and heat-resistant steel Duplex steels and their types Alloy 01X18H40M5G2TFRY (EP753U) Alloy 01X18H40M5GB (EP753; ČS116) Alloy 01X18H40M5GBR (EP753R) Alloy 03KhN28MDT (EP516) Alloy 06XHN28MDT (EI943) Alloy 06XHN28MT (EI628) Alloy Kh33TMMDU (EK63) Alloy KhN30MDB (EK77) Alloy CrN40B (EP337) Alloy KhN40M5T2GYUBR (EK173) Alloy CrN40MDB (EP937) Alloy CrN40MDTU (EP543U) Alloy CrN46B (EP350; 0Х20Н46B) Steel 015Х16Н15М3 Steel 02X17H14M3 02Cr18Ni11 steel Steel 02Х21Н21М4Г2Б (ЗИ69) Steel 02Х21Н25М5ДБ (EC5) Steel 02Х25Н22АМ2 (ChS108) Steel 03Х11Н10М2Т2 (EP853) Steel 03Х12К10М6Н4Т (EP927) Steel 03Х12Н10МТР (EP810; VNS-25) Steel 03X13AG19 (ChS36) Steel 03Х15Н35Г7М6Б (EP855) Steel 03Х16Н15М3 (ЭИ844) Steel 03X17AN9 (EK177) Steel 03Х17Н14М2 Steel 03X18N11 (000X18N11) Steel 03Х18Н12 (000Х18Н12) Steel 03Х18Н12Т (000Х18Н12Т) Steel 03Х20Н45М5Б (ChS32; 03ХН45МБ) Steel 03Х21Н21М4ГБ (ЗИ35) Steel 03Х21Н25М5ДБ Steel 03Х22Н6М2 (ЗИ67) Steel 03Х23Н6 (ЗИ68) Steel 04X17H10M2 04X15ST steel 04X17T steel Steel 04X18H10 (EI842) Steel 04X19MAFT Steel 04Х25Н5М2 (DI62) Steel 04Х32Н8 (EP535) Steel 05Х12Н2К3М2АФ (VNS-40) Steel 05Х12Н9М2С3 (EP821) Steel 05Х20Н15АГ6 (ChS109) 05KhGB steel Steel 06Х12Н3Д (08Х12Н3Д) Steel 06Х12Н3Д 06X13H4DM steel Steel 06Х14Н6Д2МБТ (EP817) 06X15H4DM steel Steel 06X18H11 (EI684) Steel 07Х16Н6 Steel 07Х15Н7М2 (EP35; СН-4; Х15Н8М2Ю) Steel 07Х16Н4Б Steel 07Х16Н6 (EP288; СН-2А; Х16Н6) Steel 07X18N10P (EP287) Steel 07X21G7AN5 (EP222) Steel 08Х10Н16Т2 (0Х10Н16Т2) Steel 08Х10Н20Т2 (0Х10Н20Т2) Steel 08Х17Н13М2Т (0Х17Н13М2Т; ЭИ448) Steel 08Х17Н15М3Т (ЭИ580) Steel 08Х17Н5М3 (ЭИ925) Steel 08Cr17Ni6T (DI-21) Steel 08Х18Г8Н2Т (KO-3) Steel 08X18H12B (EI402) Steel 08Cr18Ni12T (0Cr18Ni12T) Steel 08X18H4G11AF (HH-3F) Steel 08X18H5G11BAF (HH-3BF) Steel 08Cr18Ni5G12AB (HH-3B) Steel 08Х18Н7Г10АМ3 (08Х18Н7Г10АМ3С2) Steel 08X18Th (DI-77) Steel 08Х20Н4АГ10 (НН-3) Steel 08Х21Г11А6 (VNS-53) Steel 08Х22Н6Т (EP53) Steel 08ХГСДП Steel 09Х15Н8Ю1 (09Х15Н8Ю; ЭИ904) Steel 09Х16Н4Б (EP56; 1Х16Н4Б) Steel 09Х17Н7Ю (ЭИ973) Steel 09Cr17N7Yu1 (0Cr17N7Yu1) Steel 10Х14АГ15 (DI-13) Steel 10Х14Г14Н3 (DI-6) Steel 10Х17Н13М2Т (ЭИ448) Steel 10Х17Н13М3Т (ЭИ432) Steel 10Х17Н5М2 (EP405) Steel 10Х18Н5Г9АС4 (EP492; VNS-3) Steel 10Х32Н4Д (EP529) Steel 11Х13Н3 Steel 12Х13Г12АС2Н2 (DI50) Steel 12X17G9AN4 (EI878) Steel 12Х17Н8Г2С2МФ (ЗИ126) Steel 12X18H10E (EP47) Steel 12Х18Н13АМ3 (EP878) Steel 12Х21Н5Т (ЭИ811; 1Х21Н5Т) Steel 13Х18Н10Г3С2М2 (ЗИ98) Steel 15Х17АГ14 (ЭП213) Steel 15Х18Н12С4ТЮ (ЭИ654; 2Х18Н12С4ТЮ) 18X13H3 steel Steel 20Х13Н4Г9 (ЭИ100) Steel 20X17H2 (2X17H2) Steel 25Х13Н2 (ЭИ474) Steel 25X17H2 (EP407) Steel 25X17H2B Steel 26Х14Н2 (EP208) Steel 30X13 (3X13) Steel 40X13 (4X13) Steel 65X13 Steel 95X13M3K3B2F (EP766) Steel 95X18 (EI229) Cr17N14M2T steel Cr17N14M3T steel Steel 015N18K13M5TU (EP948; ČS35) Steel 015N18M4TU (EP989; ČS5U) Steel 015Cr18Nr15P09 (EP166A) Steel 015Х18Н15Р13 (EP166Б) Steel 015Cr18Nr15P17 (EP167A) Steel 015Cr18Nr15P22 (EP167B) Steel 015Х18Н15Р26 (EP168А) Steel 015Cr18Nr15P30 (EP168B) Steel 01N18K9M5T (EP637U) Steel 02N15K10M5F5 Steel 02N18M3K3T (EK165; ČS101) Steel 02X8H22S6 (EP794) Steel 03N10Cr12D2T Steel 03N14H5M3T (EP777) Steel 03N14Cr5M3Tu (OMC-2) Steel 03N15K10M5F5 (EK169) Steel 03N17K10V10MT (EP836) Steel 03N18K1M3TU (ZI80) Steel 03N18K8M3TU (ЗИ25) Steel 03N18K9M5TU (ChS4) Steel 03N18M3TU (ChS5) Steel 03N18M4TU (ChS25) Steel 03Х11Н10М2Т (EP678; VNS-17) Steel 03Х11Н10М2Т1 (EP679) Steel 03Х12Н8К5М2ТЮ (ЗИ90) Steel 03Х12Н8МТю (ЗИ37) Steel 03Х13Н5М5К9 (VNL-6) Steel 03Х17Н14М3 (ЗИ66) Steel 04Х16Н11М3Т (DI95) Steel 05X12H2M Steel 05Х12Н5К14М5ТВ (EP695) Steel 06X13H7D2 (EP898) Steel 06Х15Н6МВФБ (VNS16) Steel 06Х16Н15М2Г2ТФР (ЧС68) Steel 06Х16Н15М3БР (EP172) Steel 07Х12НМБФ (EP609) Steel 07Х12НМФБ (ChS80) Steel 07Х15Н30В5М2 (ChS81) Steel 07Х25Н16АГ6Ф (EP750) Steel 08Cr13 (EI496) Steel 08Х14Н2К3МФБ (EK93; VNS-51) Steel 08Х16Н11М3 Steel 08X19H12TF Steel 08Х20Н12АБФ Steel 09X17N (ChS130) 09Cr18Ni9 steel Steel 10Х12Н20Т2 (EP452) Steel 10Х12Н3М2БФ 10X18N10T steel (EP502) 10X18H9 steel Steel 10Х20Н33Б Steel 10Х25Н6АТМФ Steel 11Х17Н Steel 12Х12М1БФР (EP450) Steel 12Х18Н9 (Х18Н9) Steel 13Х16Н3М2АФ (VNS57) Steel 14Х17Н2 (ЭИ268) Steel 14Х20Н25В5МБ (LZhT) Steel 15Х16Н2АМ (EP479) Steel 16Х12В2ФТаР (EC181) Steel 17Х18Н9 (2Х18Н9) Steel 20Х12НМВБФАР (ЧС139) Steel 20X13 (02X13) Steel 20Х13Н2ДМЮФ (DI96) Steel 23Х15Н5АМ3 (18Х15Н6АМ3; VNS-9) Steel 30X23H7S Steel 32Х13Н6К3М2БДЛТ (VNS-32; SES1) Steel 35Х24Н24Б Steel 45X25H20S Steel 45X25H20C2 45X25H35BS steel Steel 45Х28Н49В5С Steel 4Х13Н6ЛВФ (EP354) Steel 50Kh15MFasch Steel 50Х20Н35С2Б Steel 50Х25Н35В5К15С Steel 50X25H35S2B Steel 80X20NS (EP992) Steel 9Х13Н6ЛК4 (ЭИ928) Steel CS 116-ID (EP753U-ID) Steel 015Cr18M2B (EP882) Steel 01X18 (ChS86) Steel 01X18M2T (ChS77) Steel 01X18T (ChS74) Steel 01X13MBSch (EP933) Steel 01X25M2T (ChS78) Steel 01X25T (ChS75) Steel 01Х25ТБЮ (ChS76; 01Х25ТБ) Steel 03Х11Н8М2Ф (DI52) Steel 03Х17Н8Г5МФАБ (VNS-31) Steel 03Cr18Ni10T (03Cr18Ni10T; Cr18Ni10T) Steel 03X20Yu3NTB (KO-4) 05Cr18Ni10T (0Cr18Ni10T) steel Steel 06Х16Н2К5ФМБ (EP875; VNS-26) Steel 06Х18Г9Н5АБ (06Х18Г5Н5АБ; ЧС51) Steel 06X18H10T (06X18H10) Steel 06X20H14C2 Steel 08Cr17T (EI645) Steel 08Cr18Ni10 (EI119) Steel 08Cr18Ni10T (EI914) Steel 08X18T1 (0X18T1) Steel 08Х20Н14С2 (ЭИ732) Steel 09Cr18Ni10T (1Cr18Ni10T) Steel 10Х13Г18Д (DI-61; 12Х13Г18Д) Steel 10Х15Н27Т3МР (EP700) Steel 12X17 (X17) Steel 12Х20Н14С2 (ЭИ732) Steel 13Х13С2М2 (ЭИ852) Steel 15X25T (EI439) Steel 15X28 (EI349) Steel 20Х20Н14С2 (ЭИ211) 4X18H2M steel (EP378) Steel 015Х14Н19С6Б (ChS110) Steel 015Х20Н25Г2Б (EP754) Steel 02Х24Н6АМ3 (DI91) Steel 03N18K9M5T (EP637; MS200) Steel 03Х16Н15М3Б (026Х16Н15М3Б; ЭИ844Б) Steel 03Х18Н9Т (Х18Н9Т) Steel 03Х19Н15Г6М2АВ2 (ChS39) Steel 03Х21Н32М3Б (EP864; ČS33) Steel 03Х24Н6АМ3 (ЗИ130) Steel 03Х9К14Н6М3Д (EP921; 03Х9К14Н6М3ДФ) Steel 04Х11Н9М2Д2 (EP832; 04Х11Н9М2Д2ТЮ) Steel 04Х13Н4АГ20 (ChS52) Steel 04Х14К13Н4М3ТВ (EP767) Steel 05Х15Н9Г6АМ (ChS31) Steel 05Х21Н12Г2БРч (DI94) Steel 07X13AG20 (ChS46) 08X14F steel Steel 08Х20Н5АГ12МФ (DI8) Steel 08Х21Н6М2Т (EP54) Steel 10Х12Н3М2ФА (ЦД-М) Steel 10Х12НД (0Х12НД) Steel 10Х13Г12БС2Н2Д2 (DI59) Steel 10X18G14AN4 (EP197; X18G14AN4) Steel 10Х32Н8 (EP263; Х32Н8) Steel 10Х9МФБ (DI82) Steel 12Х11В2МФ (ЭИ756) Steel 12X13 (1X13) Steel 12X18H10T (X18H10T) Steel 12Х18Н12Т (Х18Н12Т) 12X18H9SMR steel (EP414; Х18Н9СМР) Steel 12Х18Н9Т (Х18Н9Т) Steel 16Х20К6Н2МВФ (EP768; VNS-22) Steel 19Х20Н4АМ3Д2С (EC7) Steel 90G29Yu9VBM (DI38; 90G29Yu9VMBF; DI38F)


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 /
Super 25 6.5 3.5 0.25 - - 1.5
Zeron 100 1.4501 /
Super 25 7 3.2 0.25 - 0.7 0.7
2507 1.4410 /
Super 25 7 4 0.27 - - -
2205 1.4462 /
S31803 /
Standard 22 5.7 3.1 0.17 - - -
2304 1.4362 /
Low alloyed 23 4.8 0.3 0.10 - - -
RDN 903 1.4482 /
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 /
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 /
Austenitic 44
2507 1.4410 /
Duplex 43
Ferrinox 255 /
Uranus 2507Cu
1.4507 /
S32520 /
Duplex 41
Zeron 100 1.4501 /
Duplex 41
2205 1.4462 /
S31803 /
Duplex 35
904L 1.4539 /
Austenitic 34
DX2202 1.4062 / S32202 Duplex 27
2304 1.4362 /
Duplex 26
2101 LDX 1.4162 /
Duplex 26
316L 2.5 Mo 1.4435 Austenitic 26
444 1.4521 /
Ferritic 24
316 1.4401 /
Austenitic 24
RDN 903 1.4482 /
Duplex 22
441 1.4509 /
Ferritic nineteen
304 1.4301 /
Austenitic nineteen
430 1.4016 /
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.


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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