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duplex-1.4462


duplex-1.4462 stainless steels are extremely corrosion resistant, work hardenable alloys. Their microstructures consist of a mixture of austenite and ferrite phases. As a result, duplex stainless steels display properties characteristic of both austenitic and ferritic stainless steels

Chemical Composition

Spec: EN 10088-2:2005

1.4462 Steel

Chemical Element % Present
Carbon (C) 0.0 - 0.03
Chromium (Cr) 21.00 - 23.00
Manganese (Mn) 0.0 - 2.00
Silicon (Si) 0.0 - 1.00
Phosphorous (P) 0.0 - 0.03
Sulphur (S) 0.0 - 0.02
Nickel (Ni) 4.50 - 6.50
Nitrogen (N) 0.10 - 0.22
Molybdenum (Mo) 2.50 - 3.50
Iron (Fe) Balance

Properties

Physical Property Value
Density 7.805 g/cm³
Thermal Expansion 13.7 x10^-6 /K
Modulus of Elasticity 200 GPa
Thermal Conductivity 19.0 W/m.K
Electrical Resistivity 0.085 x10^-6 Ω .m

Spec: EN 10088-2:2005

Sheet - Up to 8mm thick

Mechanical Property Value
Proof Stress 500 Min MPa
Tensile Strength 700 to 950 MPa
Elongation A50 mm 20 Min %

Spec: EN 10088-2:2005

Plate - over 8mm to 13.5mm Thick

Mechanical Property Value
Proof Stress 460 Min MPa
Tensile Strength 700 to 950 MPa
Elongation A50 mm 25 Min %

Spec: EN 10088-2:2005

Plate - Over 13.5mm to 75mm Thick

Mechanical Property Value
Proof Stress 460 Min MPa
Tensile Strength 640 to 840 MPa
Elongation A50 mm 25 Min %

Applications

Duplex stainless steels are typically used in:
~ Chemical processing, transport and storage
~ Oil and gas exploration and offshore rigs
~ Oil and gas refining
~ Marine environments
~ Pollution control equipment
~ Pulp & paper manufacturing
~ Chemical process plant

Corrosion Resistance

Duplex stainless steels are extremely corrosion resistant. They have high resistance to intergranular corrosion. Even in chloride and sulphide environments, duplex stainless steels exhibit very high resistance to stress corrosion cracking.
The super duplex grades are even more resistant to corrosion.

Heat Resistance

The high chromium content of duplex stainless steels that protects against corrosion, causes embrittlement at temperatures over about 300°C. At low temperatures duplex stainless steels have better ductility than the ferritic and martensitic grades. Duplex grades can readily be used down to at least -50°C.

Fabrication

Fabrication of all stainless steels should be done only with tools dedicated to stainless steel materials. Tooling and work surfaces must be thoroughly cleaned before use. These precautions are necessary to avoid cross contamination of stainless steel by easily corroded metals that may discolour the surface of the fabricated product.

Machinability

Although machinable, the high strengths of duplex stainless steels makes machining difficult. As an example, machining of 2205 is around 20% slower than for 304.
Machining can be enhanced by using the following rules:
~ Cutting edges must be kept sharp. Dull edges cause excess work hardening.
~ Cuts should be light but deep enough to prevent work hardening by riding on the surface of the material.
~ Chip breakers should be employed to assist in ensuring swarf remains clear of the work
~ Low thermal conductivity of austenitic alloys results in heat concentrating at the cutting edges. This means coolants and lubricants are necessary and must be used in large quantities.

Heat Treatment

Duplex stainless steels cannot be hardened by heat treatment. They can however be work hardened.
Solution treatment or annealing can be done by rapid cooling after heating to around 1100°C.

Weldability

Duplex stainless steels have good weldability. All standard welding processes can be used. They are not quite as easily welded as the austenitic grades but low thermal expansion in duplex grades reduces distortion and residual stresses after welding. The recommended filler material for 2205 stainless steel is 2209.