dublex steel
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DUPLEX STEEL

We are Roll-Fast Supplies A Full Range Of Duplex 2205 Fasteners, Duplex Steel Fixings, Duplex 2205 Hex Bolts, Duplex Stainless Steel Fasteners, Duplex Bolts S31803 At best price In India.

Duplex stainless steels are called “duplex” because they have a two-phase microstructure consisting of grains of ferritic and austenitic stainless steel. The picture shows the yellow austenitic phase as “islands” surrounded by the blue ferritic phase. When duplex stainless steel is melted it solidifies from the liquid phase to a completely ferritic structure. As the material cools to room temperature, about half of the ferritic grains transform to austenitic grains (“islands”). The result is a microstructure of roughly 50% austenite and 50% ferrite.

Duplex stainless steel was developed in Sweden in 1930, but commercial production didn’t commence until the 1970s due to the very complicated process of its production. There has been a re-emergence in the steel in modern times after significant advances in steelmaking techniques have made it easier to produce it. However, they are still a relatively under-utilized group of stainless steels, with the world’s usage only between 1 – 3% due to the limitations of their application.

We are the biggest producers for bigger diameter bolts and nuts in India, as our name suggests we are manufacturing big bolts and nuts in Duplex steel grades in the under mentioned table.

We manufacture duplex steel bolts as per grade Alloy 2205, DUPLEX steel is a mix of Austenite and Ferratic steel microstructure, which is why they are also known as Duplex steel. They also have great resistance to corrosion and have higher strength as compared to stainless steel grades like 316 or 304.

We have in house storage of Hex & round Duplex Steel bars as per customer item required.

  • The properties of duplex stainless steel

The microstructure of duplex stainless steels features both the crystallographic structures of approximately 50% ferrite (a body-centred cubic structure) and 50% austenite (a face-centred cubic structure). Both of these phases co-exist as a stable mixture, unlike two-phase alloys, where one of the two phases manifests as precipitates. The alloying elements in duplex stainless steels are either ferritisers (e.g. chromium, silicon, molybdenum) or austenitisers (e.g. carbon, nickel, nitrogen), which means they favour the formation of the ferritic and austenitic phases, respectively.

Properties of selected heat treated duplex steel grades (all values taken at 20 °C).

 


ASTM A789 Grade S32520 Heat-Treated

ASTM A790 Grade S31803 Heat-Treated

ASTM A790 Grade S32304 Heat-Treated

ASTM A815 Grade S32550 Heat-Treated

ASTM A815 Grade S32205 Heat-Treated

Elastic modulus

200 GPa 

200 GPa 

200 GPa 

200 GPa 

200 GPa 

Elongation

25 % 

25 % 

25 % 

15 % 

20 % 

Tensile strength

770 MPa 

620 MPa 

600 MPa 

800 MPa 

655 MPa 

Hardness, Brinell

310

290

290

302

290

Yield strength

550 MPa 

450 MPa 

400 MPa 

550 MPa 

450 MPa 

Coefficient of thermal expansion

1E-5 1/K 

1E-5 1/K 

1E-5 1/K 

1E-5 1/K 

1E-5 1/K 

Specific heat capacity

440 - 502 J/(kg·K) 

440 - 502 J/(kg·K) 

440 - 502 J/(kg·K) 

440 - 502 J/(kg·K) 

440 - 502 J/(kg·K) 

Thermal conductivity

13 - 30 W/(m·K) 

13 - 30 W/(m·K) 

13 - 30 W/(m·K) 

13 - 30 W/(m·K) 

13 - 30 W/(m·K) 

  • The Grades of duplex stainless steels

Duplex stainless steels are usually divided into three groups based on their pitting corrosion resistance, characterised by the pitting resistance equivalence number, PREN = %Cr + 3.3 %Mo + 16 %N.

Standard duplex (PREN range: 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: 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, Ni, 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. Applications include deepwater offshore oil production.

Type

Example grades

Composition

PREN

Cr%

Ni%

Mo%

N%

Lean

S31500, S32304, S32404

20-24

1-5

0.1-0.3

0.1-0.22

24-25

Standard

S31803, S32205

21-23

4.5-6

2.5-3.5

0.1-0.22

33-35

Super-duplex

S32520, S32550, S32750

24-29

4.5-8

2.7-4.5

0.1-0.35

>40

Hyper-duplex

S32707, S33207

27

6.5

5

0.4

49

Duplex stainless steel sub-groups

Lean duplex grades (PREN range: 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.

Duplex stainless steel applications

Due to the limitations of duplex stainless steels such as poor formability and machinability, in addition to their highly complicated metallurgical process of production compared to ferritic, austenitic and martensitic stainless steels, duplex steels are used mostly for niche applications.

Applications of duplex stainless steels take into account their limitations and advantages, but the major applications require corrosion resistance, such as pitting and crevice corrosion resistance, stress corrosion resistance, fatigue corrosion, abrasion corrosion or resistance to corrosive environments that are acidic or caustic. Some of the common industrial applications are our duplex products used outlined below.

  • Paper production Plants
  • Desalination Plants
  • Oil and Gas Plants
  • Construction industry
  • Food and Drink Storage Plants

Composition by Weight (%)

Steel designation

Number

C, max.

Si

Mn

P, max.

S, max.

N

Cr

Cu

Mo

Ni

Other

X2CrNiN22-2

1.4062

0.03

≤1.00

≤2.00

0.04

0.01

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

0.03

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

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

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

0.04

≤1.00

4.0 to 6.0

0.04

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

0.03

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

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

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

1.446

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

1.441

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

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

0.03

≤0.50

0.80 to 1.50

0.03

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

0.03

≤0.50

≤1.50

0.035

0.01

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

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 at room temperature of solution-annealed austenitic–ferritic stainless steels

0.2% proof stress, min. (MPa)

Ultimate tensile strength (MPa)

Elongation, min. (%)

 

 

X2CrNiN23-4

1.4362

400

600 to 830

25

X2CrNiMoN22-5-3

1.4462

450

650 to 880

25

X3CrNiMoN27-5-2

1.446

450

620 to 680

20

X2CrNiN22-2

1.4062

380

650 to 900

30

X2CrCuNiN23-2-2

1.4669

400

650 to 900

25

X2CrNiMoSi18-5-3

1.4424

400

680 to 900

25

X2CrMnNiN21-5-1

1.4162

400

650 to 900

25

X2CrMnNiMoN21-5-3

1.4482

400

650 to 900

25

X2CrNiMnMoCuN24-4-3-2

1.4662

450

650 to 900

25

X2CrNiMoCuN25-6-3

1.4507

500

700 to 900

25

X2CrNiMoN25-7-4

1.441

530

730 to 930

25

X2CrNiMoCuWN25-7-4

1.4501

530

730 to 930

25

X2CrNiMoN29-7-2

1.4477

550

750 to 1000

25

X2CrNiMoCoN28-8-5-1*

1.4658

650

800 to 1000

25

Duplex SS Fasteners & Components are produced from an alloy that has a high content of chromium and low to moderate content of nickel. The high chromium content in the Duplex Stainless Steel Fasteners & Components gives them high tensile strength along with increased hardness and toughness. Therefore Duplex Stainless Steel Fasteners are less likely to get damaged or deformed and get dented. Another reason for the Duplex Stainless Fasteners having good mechanical properties can be attributed to the mixed, yet balanced austenite and ferrite microstructure present in the alloy.

Some few products below are we manufacture in duplex steel.

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