771.0 (71A, A07710) Cast Aluminum
771.0 aluminum is an aluminum alloy formulated for casting. 771.0 is the Aluminum Association (AA) designation for this material. A07710 is the UNS number. It has a moderately high melting temperature among the ANSI/AA cast aluminums in the database.
The properties of 771.0 aluminum include seven common variations. This page shows summary ranges across all of them. For more specific values, follow the links immediately below. The graph bars on the material properties cards further below compare 771.0 aluminum to: ANSI/AA cast aluminums (top), all aluminum 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
Brinell Hardness
85 to 120
Elastic (Young's, Tensile) Modulus
70 GPa 10 x 106 psi
Elongation at Break
1.7 to 6.5 %
Fatigue Strength
92 to 180 MPa 13 to 26 x 103 psi
Poisson's Ratio
0.32
Shear Modulus
26 GPa 3.8 x 106 psi
Tensile Strength: Ultimate (UTS)
250 to 370 MPa 36 to 54 x 103 psi
Tensile Strength: Yield (Proof)
210 to 350 MPa 30 to 51 x 103 psi
Thermal Properties
Latent Heat of Fusion
380 J/g
Maximum Temperature: Mechanical
180 °C 350 °F
Melting Completion (Liquidus)
630 °C 1160 °F
Melting Onset (Solidus)
620 °C 1150 °F
Solidification (Pattern Maker's) Shrinkage
1.6 %
Specific Heat Capacity
870 J/kg-K 0.21 BTU/lb-°F
Thermal Conductivity
140 to 150 W/m-K 80 to 86 BTU/h-ft-°F
Thermal Expansion
24 µm/m-K
Electrical Properties
Electrical Conductivity: Equal Volume
27 % IACS
Electrical Conductivity: Equal Weight (Specific)
82 % IACS
Otherwise Unclassified Properties
Base Metal Price
9.5 % relative
Density
3.0 g/cm3 190 lb/ft3
Embodied Carbon
8.0 kg CO2/kg material
Embodied Energy
150 MJ/kg 64 x 103 BTU/lb
Embodied Water
1130 L/kg 140 gal/lb
Common Calculations
Resilience: Ultimate (Unit Rupture Work)
4.4 to 20 MJ/m3
Resilience: Unit (Modulus of Resilience)
310 to 900 kJ/m3
Stiffness to Weight: Axial
13 points
Stiffness to Weight: Bending
46 points
Strength to Weight: Axial
23 to 35 points
Strength to Weight: Bending
29 to 39 points
Thermal Diffusivity
54 to 58 mm2/s
Thermal Shock Resistance
11 to 16 points
Alloy Composition
Among cast aluminum alloys, the composition of 771.0 aluminum is notable for containing a comparatively high amount of zinc (Zn) and including chromium (Cr). Zinc is used to achieve significant increases in strength, at the cost of increased susceptibility to stress corrosion cracking. Among other things, this limits weldability. Chromium is used to limit grain growth during hot working or heat treatment, which improves ductility and toughness. Chromium also reduces the alloy's susceptibility to stress corrosion cracking. If the alloy is anodized, the presence of chromium will tend to add a yellow tint to the film.
| Al | 90.5 to 92.5 | |
| Zn | 6.5 to 7.5 | |
| Mg | 0.8 to 1.0 | |
| Ti | 0.1 to 0.2 | |
| Cr | 0.060 to 0.2 | |
| Si | 0 to 0.15 | |
| Fe | 0 to 0.15 | |
| Mn | 0 to 0.1 | |
| Cu | 0 to 0.1 | |
| res. | 0 to 0.15 |
All values are % weight. Ranges represent what is permitted under applicable standards.
Followup Questions
Similar Alloys
Further Reading
ASTM B618: Standard Specification for Aluminum-Alloy Investment Castings
ASTM B26: Standard Specification for Aluminum-Alloy Sand Castings
Handbook of Aluminum vol. 2: Alloy Production and Materials Manufacturing, George Totten and D. Scott MacKenzie (editors), 2003
ASM Specialty Handbook: Aluminum and Aluminum Alloys, J. R. Davis (editor), 1993