ASTM B631 Class A Silver-Tungsten Electrical Contact Alloy
ASTM B631 class A is a precious metal alloy formulated for use in electrical contacts. It has the lowest embodied energy among the precious metal electrical contact alloys in the database.
The properties of ASTM B631 class A 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 A 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
220 GPa 32 x 106 psi
Poisson's Ratio
0.3
Rockwell B Hardness
63 to 98
Shear Modulus
85 to 86 GPa 12 x 106 psi
Thermal Properties
Latent Heat of Fusion
160 J/g
Melting Completion (Liquidus)
2680 to 2690 °C 4850 to 4880 °F
Specific Heat Capacity
160 J/kg-K 0.038 to 0.039 BTU/lb-°F
Thermal Conductivity
420 W/m-K 240 BTU/h-ft-°F
Thermal Expansion
11 µm/m-K
Electrical Properties
Electrical Conductivity: Equal Volume
40 to 47 % IACS
Electrical Conductivity: Equal Weight (Specific)
25 to 29 % IACS
Otherwise Unclassified Properties
Density
15 g/cm3 910 lb/ft3
Embodied Carbon
43 kg CO2/kg material
Embodied Energy
670 MJ/kg 290 x 103 BTU/lb
Common Calculations
Stiffness to Weight: Axial
8.5 points
Stiffness to Weight: Bending
14 points
Thermal Diffusivity
180 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