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ASTM B522 Class II Gold-Silver-Platinum Electrical Contact Alloy

ASTM B522 class II is a precious metal alloy formulated for use in electrical contacts.

The properties of ASTM B522 class II 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 ASTM B522 class II 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

96 GPa 14 x 106 psi

Elongation at Break

1.1 to 28 %

Knoop Hardness

88 to 150

Poisson's Ratio


Shear Modulus

34 GPa 5.0 x 106 psi

Shear Strength

180 to 280 MPa 26 to 40 x 103 psi

Tensile Strength: Ultimate (UTS)

280 to 490 MPa 40 to 70 x 103 psi

Tensile Strength: Yield (Proof)

120 to 210 MPa 17 to 30 x 103 psi

Thermal Properties

Latent Heat of Fusion

77 J/g

Melting Completion (Liquidus)

1030 °C 1890 °F

Melting Onset (Solidus)

1030 °C 1880 °F

Specific Heat Capacity

160 J/kg-K 0.037 BTU/lb-°F

Thermal Expansion

15 µm/m-K

Other Material Properties


17 g/cm3 1070 lb/ft3

Electrical Conductivity: Equal Volume

11 % IACS

Electrical Conductivity: Equal Weight (Specific)

5.7 % IACS

Common Calculations

Resilience: Ultimate (Unit Rupture Work)

4.4 to 63 MJ/m3

Resilience: Unit (Modulus of Resilience)

75 to 230 kJ/m3

Stiffness to Weight: Axial

3.1 points

Stiffness to Weight: Bending

8.9 points

Strength to Weight: Axial

4.4 to 7.8 points

Strength to Weight: Bending

5.5 to 8.0 points

Thermal Shock Resistance

13 to 24 points

Alloy Composition

Gold (Au)Au 68.5 to 69.5
Silver (Ag)Ag 24.5 to 25.5
Platinum (Pt)Pt 5.5 to 6.5
Sulfur (S)S 0 to 0.010
Residualsres. 0 to 0.26

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

Followup Questions

Similar Alloys

Further Reading

ASTM B522: Standard Specification for Gold-Silver-Platinum Electrical Contact Alloy

CRC Materials Science and Engineering Handbook, 4th ed., James F. Shackelford et al. (editors), 2015