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Nickel Alloy 625 (N06625, NA21)

Nickel 625 is a nickel alloy formulated for primary forming into wrought products. NA21 is the British Standard (BS) designation for this material. N06625 is the UNS number. Nickel Alloy 625 is the common industry name. Additionally, the AFNOR (French) designation is NC22DNb.

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 a moderately high base cost among wrought nickels. In addition, it has a moderately high embodied energy and a moderately low melting temperature.

The properties of nickel 625 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 nickel 625 to: wrought nickels (top), all nickel 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 30 x 106 psi

Elongation at Break

33 to 34 %

Fatigue Strength

240 to 320 MPa 34 to 47 x 103 psi

Poisson's Ratio

0.29

Shear Modulus

79 GPa 11 x 106 psi

Shear Strength

530 to 600 MPa 77 to 87 x 103 psi

Tensile Strength: Ultimate (UTS)

790 to 910 MPa 120 to 130 x 103 psi

Tensile Strength: Yield (Proof)

320 to 450 MPa 47 to 65 x 103 psi

Thermal Properties

Curie Temperature

-200 °C -320 °F

Latent Heat of Fusion

330 J/g

Maximum Temperature: Mechanical

980 °C 1800 °F

Melting Completion (Liquidus)

1350 °C 2460 °F

Melting Onset (Solidus)

1290 °C 2350 °F

Specific Heat Capacity

440 J/kg-K 0.1 BTU/lb-°F

Thermal Conductivity

11 W/m-K 6.4 BTU/h-ft-°F

Thermal Expansion

13 µm/m-K

Electrical Properties

Electrical Conductivity: Equal Volume

1.3 % IACS

Electrical Conductivity: Equal Weight (Specific)

1.4 % IACS

Otherwise Unclassified Properties

Base Metal Price

80 % relative

Density

8.6 g/cm3 540 lb/ft3

Embodied Carbon

14 kg CO2/kg material

Embodied Energy

190 MJ/kg 83 x 103 BTU/lb

Embodied Water

290 L/kg 35 gal/lb

Common Calculations

Resilience: Ultimate (Unit Rupture Work)

220 to 250 MJ/m3

Resilience: Unit (Modulus of Resilience)

260 to 490 kJ/m3

Stiffness to Weight: Axial

13 points

Stiffness to Weight: Bending

23 points

Strength to Weight: Axial

26 to 29 points

Strength to Weight: Bending

22 to 24 points

Thermal Diffusivity

2.9 mm2/s

Thermal Shock Resistance

22 to 25 points

Alloy Composition

Nickel (Ni) 58 to 68.9
Chromium (Cr) 20 to 23
Molybdenum (Mo) 8.0 to 10
Niobium (Nb) 3.2 to 4.2
Iron (Fe) 0 to 5.0
Cobalt (Co) 0 to 1.0
Manganese (Mn) 0 to 0.5
Silicon (Si) 0 to 0.5
Aluminum (Al) 0 to 0.4
Titanium (Ti) 0 to 0.4
Carbon (C) 0 to 0.1
Phosphorus (P) 0 to 0.015
Sulfur (S) 0 to 0.015

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

Followup Questions

Similar Alloys

Further Reading

ASTM B834: Standard Specification for Pressure Consolidated Powder Metallurgy Iron-Nickel-Chromium-Molybdenum (UNS N08367) and Nickel-Chromium-Molybdenum-Columbium (Nb) (UNS N06625) Alloy Pipe Flanges, Fittings, Valves, and Parts

ASTM B443: Standard Specification for Nickel-Chromium-Molybdenum-Columbium Alloy (UNS N06625) and Nickel-Chromium-Molybdenum-Silicon Alloy (UNS N06219) Plate, Sheet, and Strip

ASTM B444: Standard Specification for Nickel-Chromium-Molybdenum-Columbium Alloys (UNS N06625) and Nickel-Chromium-Molybdenum-Silicon Alloy (UNS N06219) Pipe and Tube

ASTM B704: Standard Specification for Welded UNS N06625, UNS N06219 and UNS N08825 Alloy Tubes

ASTM B446: Standard Specification for Nickel-Chromium-Molybdenum-Columbium Alloy (UNS N06625), Nickel-Chromium-Molybdenum-Silicon Alloy (UNS N06219), and Nickel-Chromium-Molybdenum-Tungsten Alloy (UNS N06650) Rod and Bar

ASTM B705: Standard Specification for Nickel-Alloy (UNS N06625, N06219 and N08825) Welded Pipe

ASTM B564: Standard Specification for Nickel Alloy Forgings

Welding Metallurgy and Weldability of Nickel-Base Alloys, John C. Lippold et al., 2009

ASM Specialty Handbook: Nickel, Cobalt, and Their Alloys, Joseph R. Davis (editor), 2000

Engineering Properties of Nickel and Nickel Alloys, John L. Everhart, 1971