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AWS BAu-3 (P00350) Filler Metal

AWS BAu-3 is a gold-based filler metal for brazing. Cited properties are appropriate for the as-fabricated (no temper or treatment) condition. BAu-3 is the AWS designation for this material. P00350 is the UNS number.

It has a moderately low density among gold-based braze fillers. In addition, it has the highest heat capacity and the highest tensile strength.

The graph bars on the material properties cards below compare AWS BAu-3 to: gold-based braze fillers (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.

Thermal Properties

Brazing Temperature

1030 to 1090 °C 1880 to 2000 °F

Latent Heat of Fusion

160 J/g

Melting Completion (Liquidus)

1030 °C 1880 °F

Melting Onset (Solidus)

970 °C 1790 °F

Specific Heat Capacity

300 J/kg-K 0.071 BTU/lb-°F

Thermal Expansion

16 µm/m-K

Other Material Properties


13 g/cm3 780 lb/ft3

Elastic (Young's, Tensile) Modulus

110 GPa 16 x 106 psi

Poisson's Ratio


Shear Modulus

41 GPa 5.9 x 106 psi

Tensile Strength: Ultimate (UTS)

220 MPa 32 x 103 psi

Common Calculations

Stiffness to Weight: Axial

5.0 points

Stiffness to Weight: Bending

13 points

Strength to Weight: Axial

4.9 points

Strength to Weight: Bending

6.4 points

Thermal Shock Resistance

8.7 points

Alloy Composition

Copper (Cu)Cu 60.9 to 63
Gold (Au)Au 34.5 to 35.5
Nickel (Ni)Ni 2.5 to 3.5
Residualsres. 0 to 0.15

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

Followup Questions

Similar Alloys

Further Reading

AWS A5.8: Specification for Filler Metals for Brazing and Braze Welding