Duplex stainless steel

{{Short description|Stainless steel that has both austenitic and ferritic phases}}

Duplex stainless steels{{Cite book|last1=Peckner|first1=Donald|title=Handbook of Stainless Steels|last2=Bernstein|first2=I.M.|publisher=McGraw Hill|year=1977|isbn=9780070491472|chapter=chapter 8}}{{Cite book|last1=Lacombe|first1=P.|title=Les Aciers Inoxydables|last2=Baroux|first2=B.|last3=Beranger|first3=G.|publisher=Les Editions de Physique|year=1990|isbn=2-86883-142-7|chapter=chapter 18}}{{Cite book|url=http://www.imoa.info/download_files/stainless-steel/Duplex_Stainless_Steel_3rd_Edition.pdf|title=Practical Guidelines for the fabrication of Duplex Stainless Steels|last=International Molybdenum Association (IMOA)|date=2014|via=www.imoa.info|isbn=978-1-907470-09-7}}{{Cite book|url=https://pubs.kci-webshop.com/Webshop/Product/BOOKS/Duplex-Stainless-Steel---DSS-2010-Conference-Proceedings.html|title=Proceedings of the Duplex Stainless Steel Conference, Beaune (2010)|last=Charles|first=Jacques|publisher=EDP Sciences, Paris|year=2010|pages=29–82|access-date=2019-10-27|archive-date=2022-05-06|archive-url=https://web.archive.org/web/20220506081328/https://pubs.kci-webshop.com/Webshop/Product/BOOKS/Duplex-Stainless-Steel---DSS-2010-Conference-Proceedings.html|url-status=dead}}{{Cite web|url=http://www.worldstainless.org/Files/issf/non-image-files/PDF/ISSF_Duplex_Stainless_Steels.pdf|title=Duplex Stainless Steels|last=International Stainless Steel Forum|date=2020}} are a family of stainless steels. These are called duplex (or austenitic-ferritic) grades because their metallurgical structure consists of two phases, austenite (face-centered cubic lattice) and ferrite (body centered cubic lattice) in roughly equal proportions.

They provide better corrosion resistance, particularly chloride stress corrosion and chloride pitting corrosion, and higher strength than standard austenitic stainless steels such as A2/304 or A4/316. The main differences in composition, when compared with austenitic stainless steel is that duplex steels have a higher chromium content, 20–28%; higher molybdenum, up to 5%; lower nickel, up to 9% and 0.05–0.50% nitrogen. Both the low nickel content and the high strength (enabling thinner sections to be used) give significant cost benefits. Duplex steels also have higher strength. For example, a Type 304 stainless steel has a 0.2% proof strength in the region of {{cvt|280|MPa|ksi}}, a 22%Cr duplex stainless steel a minimum 0.2% proof strength of some {{cvt|450|MPa|ksi}} and a superduplex grade a minimum of {{cvt|550|MPa|ksi}}.{{cite web |last1=Dr. James Fritz |title=A Practical Guide to Using Duplex Stainless Steels |url=https://nickelinstitute.org/en/library/technical-guides/a-practical-guide-to-duplex-stainless-steels-10044/ |website=Nickel Institute}}

Duplex steels are used extensively in the offshore oil and gas industry for pipework systems, manifolds, risers, etc. and in the petrochemical industry for pipelines and pressure vessels.

Grades of duplex stainless steels

File:Microstructures of four kinds of duplex stainless steel in each direction.jpg

Duplex stainless steels are usually divided into three groups based on their pitting corrosion resistance, characterised by the pitting resistance equivalence number, {{nowrap|PREN {{=}} %Cr + 3.3{{nnbsp}}%Mo + 16{{nnbsp}}%N}}.{{Cite web|url=https://www.bssa.org.uk/topics.php?article=111|title=Calculation of Pitting Resistance Equivalent Number (PREN)|last=Bristish Stainless Steel Association|website=bssa.org.uk}}

; Standard duplex (PREN range{{colon}} 28–38): Typically Grade EN 1.4462 (also called 2205). It is typical of the mid-range of properties and is perhaps the most used today

; Super-duplex (PREN range{{colon}} 38–45): Typically grade EN 1.4410 up to so-called hyper duplex grades (PREN: >45) developed later to meet specific demands of the oil and gas as well as those of the chemical industries. They offer a superior corrosion resistance and strength but are more difficult to process because the higher contents of Cr, Mo, N and even W promote the formation of intermetallic phases, which reduce drastically the impact resistance of the steel. Faulty processing will result in poor performance and users are advised to deal with reputable suppliers/processors.{{Cite web|url=https://www.materials.sandvik/en/knowledge-center/|title=Knowledge center — Sandvik Materials Technology|website=www.materials.sandvik|language=en|access-date=2019-03-25}} Applications include deepwater offshore oil production.

; Lean duplex grades (PREN range{{colon}} 22–27): Typically grade EN 1.4362, have been developed more recently for less demanding applications, particularly in the building and construction industry. Their corrosion resistance is closer to that of the standard austenitic grade EN 1.4401 (with a plus on resistance to stress corrosion cracking) and their mechanical properties are higher. This can be a great advantage when strength is important. This is the case in bridges, pressure vessels or tie bars.

Chemical compositions

Chemicals composition of grades from EN 10088-1 (2014) Standard are given in the table below:{{Cite web|url=https://shop.bsigroup.com/SearchResults/?q=BS%20EN%2010088-1:2014|title=The standard is available from BSI Shop}}

class="wikitable" \|+ Composition by weight (%)
ISO Steel designation ! EN Number !UNS equiv{{cite web \|title=Stainless steel grades listed in the international standard ISO 15510:2010 Comparative designations of grades with similar composition from other important standards. (listed by type of steel structure and by increasing intermediate 3-digits code of the ISO name) \|url=https://www.duplexsteelalloys.com/assets/pdf/stainless-steel-grades-listed-in-the-international-standard-iso-155102010.pdf \|access-date=10 March 2023 \|website=International Stainless Steel Forum}} ! C, max. ! Si ! Mn ! P, max. ! S, max. ! N ! Cr ! Cu ! Mo ! Ni ! Other
X2CrNiN22-2 \|1.4062 \|S32202 \|0.03 \|≤1.00 \|≤2.00 \|0.04 \|0.010 \|0.16 to 0.28 \|21.5 to 24.0 \| - \|≤0.45 \|1.00 to 2.90 \| -
X2CrCuNiN23-2-2 \|1.4669 \| \|0.045 \|≤1.00 \|1.00 to 3.00 \|0.04 \|0.030 \|0.12 to 0.20 \|21.5 to 24.0 \|1.60 to 3.00 \|≤0.50 \|1.00 to 3.00 \| -
X2CrNiMoSi18-5-3 \|1.4424 \|S31500 \|0.03 \|1.40 to 2.00 \|1.20 to 2.00 \|0.035 \|0.015 \|0.05 to 0.10 \|18.0 to 19.0 \| - \|2.5 to 3.0 \|4.5 to 5.2 \| -
X2CrNiN23-4 \|1.4362 \|S32304 \|0.03 \|≤1.00 \|≤2.00 \|0.035 \|0.015 \|0.05 to 0.20 \|22.0 to 24.5 \|0.10 to 0.60 \|0.10 to 0.60 \|3.5 to 5.5 \| -
X2CrMnNiN21-5-1 \|1.4162 \|S32101 \|0.04 \|≤1.00 \|4.0 to 6.0 \|0.040 \|0.015 \|0.20 to 0.25 \|21.0 to 22.0 \|0.10 to 0.80 \|0.10 to 0.80 \|1.35 to 1.90 \| -
X2CrMnNiMoN21-5-3 \|1.4482 \| \|0.03 \|≤1.00 \|4.0 to 6.0 \|0.035 \|0.030 \|0.05 to 0.20 \|19.5 to 21.5 \|≤1.00 \|0.10 to 0.60 \|1.50 to 3.50 \| -
X2CrNiMoN22-5-3 \|1.4462 \| rowspan="2" \|S31803, S32205 \|0.03 \|≤1.00 \|≤2.00 \|0.035 \|0.015 \|0.10 to 0.22 \|21.0 to 23.0 \| - \|2.50 to 3.50 \|4.5 to 6.5 \| -
X2CrNiMnMoCuN24-4-3-2 \|1.4662 \|0.03 \|≤0.70 \|2.5 to 4.0 \|0.035 \|0.005 \|0.20 to 0.30 \|23.0 to 25.0 \|0.10 to 0.80 \|1.00 to 2.00 \|3.0 to 4.5 \|
X2CrNiMoCuN25-6-3 \|1.4507 \|S32520 \|0.03 \|≤0.70 \|≤2.00 \|0.035 \|0.015 \|0.20 to 0.30 \|24.0 to 26.0 \|1.00 to 2.50 \|3.0 to 4.0 \|6.0 to 8.0 \| -
X3CrNiMoN27-5-2 \|1.4460 \|S31200 \|0.05 \|≤1.00 \|≤2.00 \|0.035 \|0.015 \|0.05 to 0.20 \|25.0 to 28.0 \| - \|1.30 to 2.00 \|4.5 to 6.5 \| -
X2CrNiMoN25-7-4 \|1.4410 \|S32750 \|0.03 \|≤1.00 \|≤2.00 \|0.035 \|0.015 \|0.24 to 0.35 \|24.0 to 26.0 \| - \|3.0 to 4.5 \|6.0 to 8.0 \| -
X2CrNiMoCuWN25-7-4 \|1.4501 \|S32760 \|0.03 \|≤1.00 \|≤1.00 \|0.035 \|0.015 \|0.20 to 0.30 \|24.0 to 26.0 \|0.50 to 1.00 \|3.0 to 4.0 \|6.0 to 8.0 \|W 0.50 to 1.00
X2CrNiMoN29-7-2 \|1.4477 \|S32906 \|0.03 \|≤0.50 \|0.80 to 1.50 \|0.030 \|0.015 \|0.30 to 0.40 \|28.0 to 30.0 \|≤0.80 \|1.50 to 2.60 \|5.8 to 7.5 \| -
X2CrNiMoCoN28-8-5-1 \|1.4658 \|S32707 \|0.03 \|≤0.50 \|≤1.50 \|0.035 \|0.010 \|0.30 to 0.50 \|26.0 to 29.0 \|≤1.00 \|4.0 to 5.0 \|5.5 to 9.5 \|Co 0.50 to 2.00
X2CrNiCuN23-4 \|1.4655 \|S32304 \|0.03 \|≤1.00 \|≤2.00 \|0.035 \|0.015 \|0.05 to 0.20 \|22.0 to 24.0 \|1.00 to 3.00 \|0.10 to 0.60 \|3.5 to 5.5 \| -

class="wikitable"

|+ Composition by weight (%)

ISO Steel designation

! EN Number

!UNS equiv{{cite web |title=Stainless steel grades listed in the international standard ISO 15510:2010 Comparative designations of grades with similar composition from other important standards. (listed by type of steel structure and by increasing intermediate 3-digits code of the ISO name) |url=https://www.duplexsteelalloys.com/assets/pdf/stainless-steel-grades-listed-in-the-international-standard-iso-155102010.pdf |access-date=10 March 2023 |website=International Stainless Steel Forum}}

! C, max.

! Si

! Mn

! P, max.

! S, max.

! N

! Cr

! Cu

! Mo

! Ni

! Other

X2CrNiN22-2

|1.4062

|S32202

|0.03

|≤1.00

|≤2.00

|0.04

|0.010

|0.16 to 0.28

|21.5 to 24.0

| -

|≤0.45

|1.00 to 2.90

| -

X2CrCuNiN23-2-2

|1.4669

|0.045

|≤1.00

|1.00 to 3.00

|0.04

|0.030

|0.12 to 0.20

|21.5 to 24.0

|1.60 to 3.00

|≤0.50

|1.00 to 3.00

| -

X2CrNiMoSi18-5-3

|1.4424

|S31500

|0.03

|1.40 to 2.00

|1.20 to 2.00

|0.035

|0.015

|0.05 to 0.10

|18.0 to 19.0

| -

|2.5 to 3.0

|4.5 to 5.2

| -

X2CrNiN23-4

|1.4362

|S32304

|0.03

|≤1.00

|≤2.00

|0.035

|0.015

|0.05 to 0.20

|22.0 to 24.5

|0.10 to 0.60

|3.5 to 5.5

| -

X2CrMnNiN21-5-1

|1.4162

|S32101

|0.04

|≤1.00

|4.0 to 6.0

|0.040

|0.015

|0.20 to 0.25

|21.0 to 22.0

|0.10 to 0.80

|1.35 to 1.90

| -

X2CrMnNiMoN21-5-3

|1.4482

|0.03

|≤1.00

|4.0 to 6.0

|0.035

|0.030

|0.05 to 0.20

|19.5 to 21.5

|≤1.00

|0.10 to 0.60

|1.50 to 3.50

| -

X2CrNiMoN22-5-3

|1.4462

| rowspan="2" |S31803,

S32205

|0.03

|≤1.00

|≤2.00

|0.035

|0.015

|0.10 to 0.22

|21.0 to 23.0

| -

|2.50 to 3.50

|4.5 to 6.5

| -

X2CrNiMnMoCuN24-4-3-2

|1.4662

|0.03

|≤0.70

|2.5 to 4.0

|0.035

|0.005

|0.20 to 0.30

|23.0 to 25.0

|0.10 to 0.80

|1.00 to 2.00

|3.0 to 4.5

X2CrNiMoCuN25-6-3

|1.4507

|S32520

|0.03

|≤0.70

|≤2.00

|0.035

|0.015

|0.20 to 0.30

|24.0 to 26.0

|1.00 to 2.50

|3.0 to 4.0

|6.0 to 8.0

| -

X3CrNiMoN27-5-2

|1.4460

|S31200

|0.05

|≤1.00

|≤2.00

|0.035

|0.015

|0.05 to 0.20

|25.0 to 28.0

| -

|1.30 to 2.00

|4.5 to 6.5

| -

X2CrNiMoN25-7-4

|1.4410

|S32750

|0.03

|≤1.00

|≤2.00

|0.035

|0.015

|0.24 to 0.35

|24.0 to 26.0

| -

|3.0 to 4.5

|6.0 to 8.0

| -

X2CrNiMoCuWN25-7-4

|1.4501

|S32760

|0.03

|≤1.00

|0.035

|0.015

|0.20 to 0.30

|24.0 to 26.0

|0.50 to 1.00

|3.0 to 4.0

|6.0 to 8.0

|W 0.50 to 1.00

X2CrNiMoN29-7-2

|1.4477

|S32906

|0.03

|≤0.50

|0.80 to 1.50

|0.030

|0.015

|0.30 to 0.40

|28.0 to 30.0

|≤0.80

|1.50 to 2.60

|5.8 to 7.5

| -

X2CrNiMoCoN28-8-5-1

|1.4658

|S32707

|0.03

|≤0.50

|≤1.50

|0.035

|0.010

|0.30 to 0.50

|26.0 to 29.0

|≤1.00

|4.0 to 5.0

|5.5 to 9.5

|Co 0.50 to 2.00

X2CrNiCuN23-4

|1.4655

|S32304

|0.03

|≤1.00

|≤2.00

|0.035

|0.015

|0.05 to 0.20

|22.0 to 24.0

|1.00 to 3.00

|0.10 to 0.60

|3.5 to 5.5

| -

Mechanical properties

Mechanical properties from European Standard EN 10088-3 (2014) (for product thickness below 160{{nbsp}}mm):

class="wikitable"

|+ Mechanical properties at room temperature of solution-annealed austenitic–ferritic stainless steels

!ISO desig.

!EN num.

! 0.2% proof stress, min

! Ultimate tensile strength

! Elongation, min (%)

X2CrNiN23-4

|1.4362

|{{cvt|400|MPa|ksi}}

|{{cvt|600|to|830|MPa|ksi}}

|25

X2CrNiMoN22-5-3

|1.4462

|{{cvt|450|MPa|ksi}}

|{{cvt|650|to|880|MPa|ksi}}

|25

X3CrNiMoN27-5-2

|1.4460

|{{cvt|450|MPa|ksi}}

|{{cvt|620|to|680|MPa|ksi}}

|20

X2CrNiN22-2

|1.4062

|{{cvt|380|MPa|ksi}}

|{{cvt|650|to|900|MPa|ksi}}

|30

X2CrCuNiN23-2-2

|1.4669

|{{cvt|400|MPa|ksi}}

|{{cvt|650|to|900|MPa|ksi}}

|25

X2CrNiMoSi18-5-3

|1.4424

|{{cvt|400|MPa|ksi}}

|{{cvt|680|to|900|MPa|ksi}}

|25

X2CrMnNiN21-5-1

|1.4162

|{{cvt|400|MPa|ksi}}

|{{cvt|650|to|900|MPa|ksi}}

|25

X2CrMnNiMoN21-5-3

|1.4482

|{{cvt|400|MPa|ksi}}

|{{cvt|650|to|900|MPa|ksi}}

|25

X2CrNiMnMoCuN24-4-3-2

|1.4662

|{{cvt|450|MPa|ksi}}

|{{cvt|650|to|900|MPa|ksi}}

|25

X2CrNiMoCuN25-6-3

|1.4507

|{{cvt|500|MPa|ksi}}

|{{cvt|700|to|900|MPa|ksi}}

|25

X2CrNiMoN25-7-4

|1.4410

|{{cvt|530|MPa|ksi}}

|{{cvt|730|to|930|MPa|ksi}}

|25

X2CrNiMoCuWN25-7-4

|1.4501

|{{cvt|530|MPa|ksi}}

|{{cvt|730|to|930|MPa|ksi}}

|25

X2CrNiMoN29-7-2

|1.4477

|{{cvt|550|MPa|ksi}}

|{{cvt|750|to|1000|MPa|ksi}}

|25

X2CrNiMoCoN28-8-5-1*

|1.4658

|{{cvt|650|MPa|ksi}}

|{{cvt|800|to|1000|MPa|ksi}}

|25

*for thickness ≤ {{cvt|5|mm|in}}

The minimum yield stress values are about twice as high as those of austenitic stainless steels.

Duplex grades are therefore attractive when mechanical properties at room temperature are important because they allow thinner sections.

475 °C embrittlement

{{Multiple image

| image1 = Aged DSS EBSD.png

| image2 = Aged DSS EBSD (austenite removed).tif

| caption1 = Electron backscatter diffraction map of 128 hrs age hardened duplex stainless steel with the ferrite phase forming the matrix and austenite grains sporadically spread. The ferrite phase volume fraction is 58%.{{Cite thesis |title=In situ full-field characterisation of strain concentrations (deformation twins, slip bands and cracks) |url=https://ora.ox.ac.uk/objects/uuid:f2ba08f3-4a27-4619-92ed-bcd3834dadf0 |publisher=University of Oxford |date=2022 |degree=PhD |language=English |first=A. |last=Mohamed Koko}}

| caption2 = EBSD map with austenite grains excluded (white). The scale bar is 500 μm. Colours denote the crystal orientation and are taken from the inverse pole figure at the lower right corner.{{Cite journal |last1=Koko |first1=Abdalrhaman |last2=Elmukashfi |first2=Elsiddig |last3=Becker |first3=Thorsten H. |last4=Karamched |first4=Phani S. |last5=Wilkinson |first5=Angus J. |last6=Marrow |first6=T. James |date=2022-10-15 |title=In situ characterisation of the strain fields of intragranular slip bands in ferrite by high-resolution electron backscatter diffraction |journal=Acta Materialia |volume=239 |pages=118284 |doi=10.1016/j.actamat.2022.118284 |issn=1359-6454|doi-access=free |bibcode=2022AcMat.23918284K }}

| total_width = 400

}}

Duplex stainless is widely used in the industry because it possesses excellent oxidation resistance but can have limited toughness due to its large ferritic grain size, and they have hardened, and embrittlement tendencies at temperatures ranging from 280 to 500 °C, especially at 475 °C, where spinodal decomposition of the supersaturated solid ferrite solution into Fe-rich nanophase ( $\acute{a}$ ) and Cr-rich nanophase ( $\acute{a}\acute{}$ ), accompanied by G-phase precipitation, occurs,{{Cite journal |last1=Örnek |first1=Cem |last2=Burke |first2=M. G. |last3=Hashimoto |first3=T. |last4=Engelberg |first4=D. L. |date=April 2017 |title=748 K (475 °C) Embrittlement of Duplex Stainless Steel: Effect on Microstructure and Fracture Behavior |journal=Metallurgical and Materials Transactions A |language=en |volume=48 |issue=4 |pages=1653–1665 |bibcode=2017MMTA...48.1653O |doi=10.1007/s11661-016-3944-2 |issn=1073-5623 |doi-access=free |s2cid=136321604}}{{Cite journal |last1=Weng |first1=K. L |last2=Chen |first2=H. R |last3=Yang |first3=J. R |date=2004-08-15 |title=The low-temperature aging embrittlement in a 2205 duplex stainless steel |url=https://www.sciencedirect.com/science/article/pii/S0921509304000590 |journal=Materials Science and Engineering: A |language=en |volume=379 |issue=1 |pages=119–132 |doi=10.1016/j.msea.2003.12.051 |issn=0921-5093}}{{Cite journal |last1=Beattie |first1=H. J. |last2=Versnyder |first2=F. L. |date=July 1956 |title=A New Complex Phase in a High-Temperature Alloy |url=https://www.nature.com/articles/178208b0 |journal=Nature |language=en |volume=178 |issue=4526 |pages=208–209 |bibcode=1956Natur.178..208B |doi=10.1038/178208b0 |issn=1476-4687 |s2cid=4217639}} which makes the ferrite phase a preferential initiation site for micro-cracks.{{Cite journal |last1=Liu |first1=Gang |last2=Li |first2=Shi-Lei |last3=Zhang |first3=Hai-Long |last4=Wang |first4=Xi-Tao |last5=Wang |first5=Yan-Li |date=August 2018 |title=Characterization of Impact Deformation Behavior of a Thermally Aged Duplex Stainless Steel by EBSD |journal=Acta Metallurgica Sinica (English Letters) |language=en |volume=31 |issue=8 |pages=798–806 |doi=10.1007/s40195-018-0708-6 |issn=1006-7191 |doi-access=free |s2cid=139395583}}

Heat treatment

class="wikitable"

|+ Recommended hot forming and annealing/soaking temperatures

! UNS No. Grade

! EN No.

! Hot forming temperature range

! Minimum soaking temperature

S32304

|1.4362

|{{cvt|1150|to|950|C|F}}

|{{cvt|980|C|F}}

S32205

|1.4462

|{{cvt|1230|to|950|C|F}}

|{{cvt|1040|C|F}}

S32750

|1.4410

|{{cvt|1235|to|1025|C|F}}

|{{cvt|1050|C|F}}

S32520

|1.4507

|{{cvt|1230|to|1000|C|F}}

|{{cvt|1080|C|F}}

S32760

|1.4501

|{{cvt|1230|to|1000|C|F}}

|{{cvt|1100|C|F}}

Duplex stainless steel grades must be cooled as quickly as possible to room temperature after hot forming to avoid the precipitation of intermetallic phases (Sigma phase in particular) which drastically reduce the impact resistance at room temperature as well as the corrosion resistance.{{Cite web|url=https://www.imoa.info/download_files/stainless-steel/IMOA_Shop_Sheet_101.pdf|title=Hot forming and Heat Treatment of Duplex Stainless Steels|last=International Molybdenum Association (IMOA)|website=www.imoa.info}}

Alloying elements Cr, Mo, W, Si increase the stability and the formation of intermetallic phases. Therefore, super duplex grades have a higher hot working temperature range and require faster cooling rates than the lean duplex grades.

Applications of duplex stainless steels

Duplex stainless steels are usually selected for their high mechanical properties and good to very high corrosion resistance (particularly to stress corrosion cracking).

Architecture
Stockholm's waterfront building {{Cite news|url=http://www.worldstainless.org/news/show/1851|title=Innovative Facades in Stainless Steel|last=Euro-Inox|work=Euro-Inox Publication, Building series|volume=19|page=34|isbn=978-2-87997-372-2}}
Louvre Abu Dhabi{{Cite news|url=https://www.imoa.info/molybdenum-media-centre/downloads/moly-review.php|title=Louvre Abu Dhabi: A rain of light|last=International Molybdenum Association|work=Moly Review|year=2019|issue=1}}
La Sagrada Familia{{Cite news|url=http://www.cedinox.es/es/publicaciones/revista-acero-inoxidable/index.html|title=Basilica de la Sagrada familia|date=June 2018|work=Acero Inoxidable|publisher=Cedinox|issue=82}}
Infrastructure:
Helix Bridge, Singapore {{Cite news|url=http://www.worldstainless.org/architecture_building_and_construction_applications/structural_applications|title=Helix Pedestrian Bridge|last=Steel Construction Institute|date=2012}}
Cala Galdana bridge {{Cite web|url=http://www.worldstainless.org/architecture_building_and_construction_applications/structural_applications|title=Cala Galdana Bridge|date=2010|publisher=Steel Construction Institute}}
Hong Kong–Zhuhai–Macau bridge and undersea tunnel {{Cite web|title=Hong Kong-Zhuhai-Macau Bridge: the world's longest sea bridge|url=https://www.roadtraffic-technology.com/projects/hong-kong-zhuhai-macau-bridge/|access-date=2021-04-29|website=www.roadtraffic-technology.com}}
sea walls, piers, etc.
tunnels
Oil and gas:
a wide range of equipment: flowlines, manifolds, risers, pumps, valves, etc.{{Cite journal|last=Zuili|first=D|date=2010|title=The use of stainless steels in oil & gas industry|url=https://pubs.kci-webshop.com/Webshop/Product/BOOKS/Duplex-Stainless-Steel---DSS-2010-Conference-Proceedings.html|journal=Proceedings of the Duplex Stainless Steel Conference|pages=575|access-date=2019-10-27|archive-date=2022-05-06|archive-url=https://web.archive.org/web/20220506081328/https://pubs.kci-webshop.com/Webshop/Product/BOOKS/Duplex-Stainless-Steel---DSS-2010-Conference-Proceedings.html|url-status=dead}}
Pulp and paper:
digesters, pressure vessels, liquor tanks, etc.{{Cite news|url=http://www.stainless-steel-world.net/pdf/SSW_pulp_LR.pdf|title=The pulp and paper industry turns to duplex|last=Chater|first=James|date=2007|work=Stainless steel world}}
Chemical engineering:
pressure vessels, heat exchangers, condensers, distillation columns, agitators, marine chemical tankers, etc.{{Cite conference|url=http://www.stainless-steel-world.net/pdf/D97_201.pdf|title=Application of Duplex Stainless Steel in the chemical process industry|last=Notten|first=G|date=1997|work=Stainless Steel World|conference=5th Duplex stainless steel world conference}}
Water:
desalination plants, large tanks for water storage, waste water treatment {{Cite book|url=https://op.europa.eu/en/publication-detail/-/publication/a4313c3e-0c7f-4261-b08d-135dd4067af2/language-en|title=Duplex stainless steels in storage tanks|author= Directorate-General for Research and Innovation|author-link=Directorate-General for Research and Innovation|publisher=EU Publication|year=2013|isbn=978-92-79-34576-0|doi=10.2777/49448}}
renewable energy: Biogas tanks
Mobility: tramcars and bus frames, tank trucks, iron ore wagons
Engineering: pumps, valves, fittings, springs, etc.

Duplex stainless steel

Grades of duplex stainless steels

Chemical compositions

Mechanical properties

475 °C embrittlement

Heat treatment

Applications of duplex stainless steels

See also

References

Further reading