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707.0 (ZG42A, A07070) Cast Aluminum

707.0 aluminum is an aluminum alloy formulated for casting. 707.0 is the Aluminum Association (AA) designation for this material. A07070 is the UNS number. Additionally, the SAE designation is 312. Older literature may refer to this material as ASTM ZG42A, but this is now discouraged.

The properties of 707.0 aluminum include four 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 707.0 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

Elastic (Young's, Tensile) Modulus

70 GPa 10 x 106 psi

Elongation at Break

1.7 to 3.4 %

Fatigue Strength

75 to 140 MPa 11 to 20 x 103 psi

Poisson's Ratio

0.33

Shear Modulus

26 GPa 3.8 x 106 psi

Tensile Strength: Ultimate (UTS)

270 to 300 MPa 40 to 44 x 103 psi

Tensile Strength: Yield (Proof)

170 to 250 MPa 25 to 36 x 103 psi

Thermal Properties

Latent Heat of Fusion

380 J/g

Maximum Temperature: Mechanical

180 °C 360 °F

Melting Completion (Liquidus)

630 °C 1170 °F

Melting Onset (Solidus)

600 °C 1110 °F

Solidification (Pattern Maker's) Shrinkage

1.6 %

Specific Heat Capacity

880 J/kg-K 0.21 BTU/lb-°F

Thermal Conductivity

150 W/m-K 85 BTU/h-ft-°F

Thermal Expansion

24 µm/m-K

Electrical Properties

Electrical Conductivity: Equal Volume

37 % IACS

Electrical Conductivity: Equal Weight (Specific)

110 % IACS

Otherwise Unclassified Properties

Base Metal Price

9.5 % relative

Density

2.9 g/cm3 180 lb/ft3

Embodied Carbon

8.3 kg CO2/kg material

Embodied Energy

150 MJ/kg 64 x 103 BTU/lb

Embodied Water

1140 L/kg 140 gal/lb

Common Calculations

Resilience: Ultimate (Unit Rupture Work)

4.3 to 8.6 MJ/m3

Resilience: Unit (Modulus of Resilience)

210 to 430 kJ/m3

Stiffness to Weight: Axial

13 points

Stiffness to Weight: Bending

47 points

Strength to Weight: Axial

26 to 29 points

Strength to Weight: Bending

32 to 34 points

Thermal Diffusivity

58 mm2/s

Thermal Shock Resistance

12 to 13 points

Alloy Composition

Among cast aluminum alloys, the composition of 707.0 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 93.6
Zinc (Zn) 4.0 to 4.5
Magnesium (Mg) 1.8 to 2.4
Manganese (Mn) 0.4 to 0.6
Iron (Fe) 0 to 0.8
Chromium (Cr) 0.2 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

Properties and Selection: Nonferrous Alloys and Special-Purpose Materials, ASM Handbook vol. 2, ASM International, 1993

CRC Materials Science and Engineering Handbook, 4th ed., James F. Shackelford et al. (editors), 2015