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.
| Al | 92.3 to 98.6 | |
| Zn | 0 to 3.3 | |
| Mg | 1.4 to 1.8 | |
| Fe | 0 to 0.8 | |
| Mn | 0 to 0.6 | |
| Cr | 0 to 0.4 | |
| Ti | 0 to 0.25 | |
| Si | 0 to 0.2 | |
| Cu | 0 to 0.2 | |
| 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 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