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Annealed ASTM B522 Class II Gold-Silver-Platinum Alloy

Annealed ASTM B522 class II is ASTM B522 class II in the annealed condition. The graph bars on the material properties cards below compare annealed 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

28 %

Knoop Hardness


Poisson's Ratio


Shear Modulus

34 GPa 5.0 x 106 psi

Shear Strength

180 MPa 26 x 103 psi

Tensile Strength: Ultimate (UTS)

280 MPa 40 x 103 psi

Tensile Strength: Yield (Proof)

120 MPa 17 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)

63 MJ/m3

Resilience: Unit (Modulus of Resilience)

75 kJ/m3

Stiffness to Weight: Axial

3.1 points

Stiffness to Weight: Bending

8.9 points

Strength to Weight: Axial

4.4 points

Strength to Weight: Bending

5.5 points

Thermal Shock Resistance

13 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

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