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705.0 (ZG32A, A07050) Cast Aluminum

705.0 aluminum is an aluminum alloy formulated for casting. 705.0 is the Aluminum Association (AA) designation for this material. A07050 is the UNS number. Additionally, the SAE designation is 311. Older literature may refer to this material as ASTM ZG32A, but this is now discouraged.

The properties of 705.0 aluminum include two common variations. This page shows summary ranges across both of them. For more specific values, follow the links immediately below. The graph bars on the material properties cards further below compare 705.0 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

62 to 65

Elastic (Young's, Tensile) Modulus

69 GPa 10 x 106 psi

Elongation at Break

8.4 to 10 %

Fatigue Strength

63 to 98 MPa 9.2 to 14 x 103 psi

Poisson's Ratio

0.33

Shear Modulus

26 GPa 3.8 x 106 psi

Tensile Strength: Ultimate (UTS)

240 to 260 MPa 35 to 38 x 103 psi

Tensile Strength: Yield (Proof)

130 MPa 18 to 19 x 103 psi

Thermal Properties

Latent Heat of Fusion

390 J/g

Maximum Temperature: Mechanical

180 °C 350 °F

Melting Completion (Liquidus)

640 °C 1180 °F

Melting Onset (Solidus)

610 °C 1130 °F

Solidification (Pattern Maker's) Shrinkage

1.6 %

Specific Heat Capacity

890 J/kg-K 0.21 BTU/lb-°F

Thermal Conductivity

140 W/m-K 79 BTU/h-ft-°F

Thermal Expansion

24 µm/m-K

Electrical Properties

Electrical Conductivity: Equal Volume

34 % IACS

Electrical Conductivity: Equal Weight (Specific)

110 % IACS

Otherwise Unclassified Properties

Base Metal Price

9.5 % relative

Density

2.8 g/cm3 170 lb/ft3

Embodied Carbon

8.4 kg CO2/kg material

Embodied Energy

150 MJ/kg 66 x 103 BTU/lb

Embodied Water

1170 L/kg 140 gal/lb

Common Calculations

Resilience: Ultimate (Unit Rupture Work)

18 to 20 MJ/m3

Resilience: Unit (Modulus of Resilience)

120 to 130 kJ/m3

Stiffness to Weight: Axial

14 points

Stiffness to Weight: Bending

49 points

Strength to Weight: Axial

24 to 26 points

Strength to Weight: Bending

31 to 32 points

Thermal Diffusivity

55 mm2/s

Thermal Shock Resistance

11 points

Alloy Composition

Among cast aluminum alloys, the composition of 705.0 aluminum is notable for including chromium (Cr) and containing a comparatively high amount of magnesium (Mg). 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. Magnesium promotes hardenability through both heat treatment and strain hardening mechanisms. It also increases susceptibility to intergranular corrosion.

Aluminum (Al) 92.3 to 98.6
Zinc (Zn) 0 to 3.3
Magnesium (Mg) 1.4 to 1.8
Iron (Fe) 0 to 0.8
Manganese (Mn) 0 to 0.6
Chromium (Cr) 0 to 0.4
Titanium (Ti) 0 to 0.25
Silicon (Si) 0 to 0.2
Copper (Cu) 0 to 0.2
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 B108: Standard Specification for Aluminum-Alloy Permanent Mold Castings

ASTM B26: Standard Specification for Aluminum-Alloy Sand Castings

Aluminum: Properties and Physical Metallurgy, John E. Hatch (editor), 1984

ASM Specialty Handbook: Aluminum and Aluminum Alloys, J. R. Davis (editor), 1993