ASTM B631 Class C Silver-Tungsten Electrical Contact Alloy
ASTM B631 class C is a precious metal alloy formulated for use in electrical contacts. It can have the highest thermal conductivity among the precious metal electrical contact alloys in the database.
The properties of ASTM B631 class C include three common variations. This page shows summary ranges across all of them. For more specific values, follow the links immediately below. The graph bars on the material properties cards further below compare ASTM B631 class C to: precious metal electrical contact alloys (top), all alloys in the same category (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
180 to 190 GPa 26 to 27 x 106 psi
Poisson's Ratio
0.32
Rockwell B Hardness
43 to 68
Shear Modulus
66 to 71 GPa 9.6 to 10 x 106 psi
Thermal Properties
Latent Heat of Fusion
140 to 150 J/g
Melting Completion (Liquidus)
2090 to 2230 °C 3800 to 4050 °F
Specific Heat Capacity
180 J/kg-K 0.043 to 0.044 BTU/lb-°F
Thermal Conductivity
450 to 490 W/m-K 260 to 290 BTU/h-ft-°F
Thermal Expansion
14 µm/m-K
Electrical Properties
Electrical Conductivity: Equal Volume
55 to 63 % IACS
Electrical Conductivity: Equal Weight (Specific)
36 to 43 % IACS
Otherwise Unclassified Properties
Density
13 to 14 g/cm3 830 to 850 lb/ft3
Embodied Carbon
55 to 59 kg CO2/kg material
Embodied Energy
860 to 920 MJ/kg 370 to 400 x 103 BTU/lb
Common Calculations
Stiffness to Weight: Axial
7.4 to 7.6 points
Stiffness to Weight: Bending
14 points
Thermal Diffusivity
180 to 200 mm2/s
Followup Questions
Further Reading
ASTM B631: Standard Specification for Silver-Tungsten Electrical Contact Materials
Tungsten: Properties, Chemistry, Technology of the Element, Alloys, and Chemical Compounds, Erik Lassner and Wolf-Dieter Schubert, 1999