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.
| Cu | 78 to 82 | |
| Zn | 7.0 to 10 | |
| Pb | 6.0 to 8.0 | |
| Sn | 2.3 to 3.5 | |
| P | 0 to 1.5 | |
| Ni | 0 to 1.0 | |
| Fe | 0 to 0.4 | |
| Sb | 0 to 0.25 | |
| S | 0 to 0.080 | |
| Si | 0 to 0.0050 | |
| Al | 0 to 0.0050 | |
| res. | 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