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UNS N08020 (2.4660) Stainless Steel

N08020 stainless steel is a superaustenitic (highly alloyed) stainless steel formulated for primary forming into wrought products. 2.4660 is the EN numeric designation for this material. N08020 is the UNS number.

This material is well established: the Further Reading section below cites a number of published standards, and that list is not necessarily exhaustive.

It has the lowest electrical conductivity among wrought superaustenitic stainless steels. In addition, it can have a moderately low ductility and has a fairly high base cost.

The properties of N08020 stainless steel include two common variations. This page shows summary ranges across both of them. For more specific values, follow the links immediately below. The graph bars on the material properties cards further below compare N08020 stainless steel to: wrought superaustenitic stainless steels (top), all iron alloys (middle), and the entire database (bottom). A full bar means this is the highest value in the relevant set. A half-full bar means it's 50% of the highest, and so on.

Mechanical Properties

Elastic (Young's, Tensile) Modulus

200 GPa 29 x 106 psi

Elongation at Break

15 to 34 %

Fatigue Strength

210 to 240 MPa 31 to 35 x 103 psi

Poisson's Ratio

0.28

Shear Modulus

77 GPa 11 x 106 psi

Shear Strength

380 to 410 MPa 55 to 59 x 103 psi

Tensile Strength: Ultimate (UTS)

610 to 620 MPa 89 to 90 x 103 psi

Tensile Strength: Yield (Proof)

270 to 420 MPa 39 to 60 x 103 psi

Thermal Properties

Latent Heat of Fusion

300 J/g

Maximum Temperature: Corrosion

490 °C 920 °F

Maximum Temperature: Mechanical

1100 °C 2010 °F

Melting Completion (Liquidus)

1410 °C 2570 °F

Melting Onset (Solidus)

1360 °C 2480 °F

Specific Heat Capacity

460 J/kg-K 0.11 BTU/lb-°F

Thermal Conductivity

12 W/m-K 7.0 BTU/h-ft-°F

Thermal Expansion

15 µm/m-K

Electrical Properties

Electrical Conductivity: Equal Volume

1.6 % IACS

Electrical Conductivity: Equal Weight (Specific)

1.8 % IACS

Otherwise Unclassified Properties

Base Metal Price

38 % relative

Density

8.2 g/cm3 510 lb/ft3

Embodied Carbon

6.6 kg CO2/kg material

Embodied Energy

92 MJ/kg 40 x 103 BTU/lb

Embodied Water

220 L/kg 26 gal/lb

Common Calculations

PREN (Pitting Resistance)

28

Resilience: Ultimate (Unit Rupture Work)

83 to 170 MJ/m3

Resilience: Unit (Modulus of Resilience)

180 to 440 kJ/m3

Stiffness to Weight: Axial

13 points

Stiffness to Weight: Bending

24 points

Strength to Weight: Axial

21 points

Strength to Weight: Bending

20 points

Thermal Diffusivity

3.2 mm2/s

Thermal Shock Resistance

15 points

Alloy Composition

Among wrought stainless steels, the composition of N08020 stainless steel is notable for containing a comparatively high amount of nickel (Ni) and including niobium (Nb). Nickel is primarily used to achieve a specific microstructure. In addition, it has a beneficial effect on mechanical properties and certain types of corrosion. Niobium is primarily used to improve yield strength, particularly at elevated temperatures.

Iron (Fe) 29.9 to 44
Nickel (Ni) 32 to 38
Chromium (Cr) 19 to 21
Copper (Cu) 3.0 to 4.0
Molybdenum (Mo) 2.0 to 3.0
Manganese (Mn) 0 to 2.0
Silicon (Si) 0 to 1.0
Niobium (Nb) 0 to 1.0
Carbon (C) 0 to 0.070
Phosphorus (P) 0 to 0.045
Sulfur (S) 0 to 0.035

All values are % weight. Ranges represent what is permitted under applicable standards.

Followup Questions

Similar Alloys

Further Reading

ASTM B729: Standard Specification for Seamless UNS N08020, UNS N08026, and UNS N08024 Nickel-Alloy Pipe and Tube

ASTM B463: Standard Specification for UNS N08020, UNS N08026, and UNS N08024 Alloy Plate, Sheet, and Strip

ASTM B464: Standard Specification for Welded UNS N08020, N08024, and N08026 Alloy Pipe

ASTM B462: Standard Specification for Forged or Rolled UNS N06030, UNS N06022, UNS N06035, UNS N06200, UNS N06059, UNS N06686, UNS N08020, UNS N08024, UNS N08026, UNS N08367, UNS N10276, UNS N10665, UNS N10675, UNS N10629, UNS N08031, UNS N06045, UNS N06025, and UNS R20033 Alloy Pipe Flanges, Forged Fittings, and Valves and Parts for Corrosive High-Temperature Service

ASTM A182: Standard Specification for Forged or Rolled Alloy and Stainless Steel Pipe Flanges, Forged Fittings, and Valves and Parts for High-Temperature Service

ASTM A276: Standard Specification for Stainless Steel Bars and Shapes

Nickel Alloys, Ulrich Heubner (editor), 1998

ASTM A240: Standard Specification for Chromium and Chromium-Nickel Stainless Steel Plate, Sheet, and Strip for Pressure Vessels and for General Applications

Welding Metallurgy of Stainless Steels, Erich Folkhard et al., 2012

ASTM A959: Standard Guide for Specifying Harmonized Standard Grade Compositions for Wrought Stainless Steels