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UNS C84400 (Alloy 5A) Valve Metal

C84400 valve metal is a brass formulated for casting. Cited properties are appropriate for the as-fabricated (no temper or treatment) condition. C84400 is the UNS number for this material. Additionally, the common industry name is 81-3-7-9. Older literature may refer to this material as ASTM Alloy 5A, but this is now discouraged.

It has a moderately low tensile strength among cast brasses. In addition, it has a moderately high base cost and a moderately low electrical conductivity.

The graph bars on the material properties cards below compare C84400 valve metal to: cast brasses (top), all copper alloys (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

100 GPa 15 x 106 psi

Elongation at Break

19 %

Poisson's Ratio

0.34

Shear Modulus

39 GPa 5.6 x 106 psi

Tensile Strength: Ultimate (UTS)

230 MPa 33 x 103 psi

Tensile Strength: Yield (Proof)

110 MPa 16 x 103 psi

Thermal Properties

Latent Heat of Fusion

180 J/g

Maximum Temperature: Mechanical

160 °C 310 °F

Melting Completion (Liquidus)

1000 °C 1840 °F

Melting Onset (Solidus)

840 °C 1550 °F

Specific Heat Capacity

370 J/kg-K 0.087 BTU/lb-°F

Thermal Conductivity

72 W/m-K 42 BTU/h-ft-°F

Thermal Expansion

19 µm/m-K

Electrical Properties

Electrical Conductivity: Equal Volume

16 % IACS

Electrical Conductivity: Equal Weight (Specific)

17 % IACS

Otherwise Unclassified Properties

Base Metal Price

29 % relative

Density

8.8 g/cm3 550 lb/ft3

Embodied Carbon

2.8 kg CO2/kg material

Embodied Energy

46 MJ/kg 20 x 103 BTU/lb

Embodied Water

340 L/kg 40 gal/lb

Common Calculations

Resilience: Ultimate (Unit Rupture Work)

36 MJ/m3

Resilience: Unit (Modulus of Resilience)

58 kJ/m3

Stiffness to Weight: Axial

6.6 points

Stiffness to Weight: Bending

18 points

Strength to Weight: Axial

7.2 points

Strength to Weight: Bending

9.4 points

Thermal Diffusivity

22 mm2/s

Thermal Shock Resistance

8.3 points

Alloy Composition

Among cast copper alloys, the composition of C84400 valve metal is notable for containing a comparatively high amount of lead (Pb). Lead is used to improve machinability and bearing properties, at the cost of toxicity. It also adds pressure tightness to castings.

Copper (Cu) 78 to 82
Zinc (Zn) 7.0 to 10
Lead (Pb) 6.0 to 8.0
Tin (Sn) 2.3 to 3.5
Phosphorus (P) 0 to 1.5
Nickel (Ni) 0 to 1.0
Iron (Fe) 0 to 0.4
Antimony (Sb) 0 to 0.25
Sulfur (S) 0 to 0.080
Silicon (Si) 0 to 0.0050
Aluminum (Al) 0 to 0.0050
Residuals 0 to 0.7

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

Followup Questions

Similar Alloys

Further Reading

ASTM B271: Standard Specification for Copper-Base Alloy Centrifugal Castings

ASTM B505: Standard Specification for Copper Alloy Continuous Castings

Copper: Its Trade, Manufacture, Use, and Environmental Status, Gunter Joseph, 2001

ASM Specialty Handbook: Copper and Copper Alloys, J. R. Davis (editor), 2001