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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.

Aluminum (Al) 90.5 to 92.5
Zinc (Zn) 6.5 to 7.5
Magnesium (Mg) 0.8 to 1.0
Titanium (Ti) 0.1 to 0.2
Chromium (Cr) 0.060 to 0.2
Silicon (Si) 0 to 0.15
Iron (Fe) 0 to 0.15
Manganese (Mn) 0 to 0.1
Copper (Cu) 0 to 0.1
Residuals 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