7178 (AlZn7MgCu, A97178) Aluminum
7178 aluminum is a 7000-series aluminum alloy: the main alloying addition is zinc and it is formulated for primary forming into wrought products. 7178 is the Aluminum Association (AA) designation for this material. In European standards, it will be given as EN AW-7178. AlZn7MgCu is the EN chemical designation. And A97178 is the UNS number.
It has been in use since 1951, but has only received its standard designation in 1954.
It can have the highest tensile strength among the 7000-series alloys in the database.
The properties of 7178 aluminum include ten 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 7178 aluminum to: 7000-series alloys (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
71 GPa 10 x 106 psi
Elongation at Break
4.5 to 12 %
Fatigue Strength
120 to 210 MPa 18 to 31 x 103 psi
Poisson's Ratio
0.32
Shear Modulus
27 GPa 3.9 x 106 psi
Shear Strength
140 to 380 MPa 21 to 55 x 103 psi
Tensile Strength: Ultimate (UTS)
240 to 640 MPa 34 to 93 x 103 psi
Tensile Strength: Yield (Proof)
120 to 560 MPa 18 to 81 x 103 psi
Thermal Properties
Latent Heat of Fusion
370 J/g
Maximum Temperature: Mechanical
180 °C 350 °F
Melting Completion (Liquidus)
630 °C 1170 °F
Melting Onset (Solidus)
480 °C 890 °F
Specific Heat Capacity
860 J/kg-K 0.2 BTU/lb-°F
Thermal Conductivity
130 W/m-K 72 BTU/h-ft-°F
Thermal Expansion
23 µm/m-K
Electrical Properties
Electrical Conductivity: Equal Volume
31 % IACS
Electrical Conductivity: Equal Weight (Specific)
91 % IACS
Otherwise Unclassified Properties
Base Metal Price
10 % relative
Density
3.1 g/cm3 190 lb/ft3
Embodied Carbon
8.2 kg CO2/kg material
Embodied Energy
150 MJ/kg 62 x 103 BTU/lb
Embodied Water
1110 L/kg 130 gal/lb
Common Calculations
Resilience: Ultimate (Unit Rupture Work)
24 to 52 MJ/m3
Resilience: Unit (Modulus of Resilience)
110 to 2220 kJ/m3
Stiffness to Weight: Axial
13 points
Stiffness to Weight: Bending
45 points
Strength to Weight: Axial
21 to 58 points
Strength to Weight: Bending
28 to 54 points
Thermal Diffusivity
47 mm2/s
Thermal Shock Resistance
10 to 28 points
Alloy Composition
Among wrought aluminum alloys, the composition of 7178 aluminum is notable for containing comparatively high amounts of zinc (Zn) and copper (Cu). 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. Copper is used to improve strength. This comes at the cost of a decrease in corrosion resistance and weldability.
| Al | 85.4 to 89.5 | |
| Zn | 6.3 to 7.3 | |
| Mg | 2.4 to 3.1 | |
| Cu | 1.6 to 2.4 | |
| Fe | 0 to 0.5 | |
| Cr | 0.18 to 0.28 | |
| Si | 0 to 0.4 | |
| Mn | 0 to 0.3 | |
| Ti | 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 B221: Standard Specification for Aluminum and Aluminum-Alloy Extruded Bars, Rods, Wire, Profiles, and Tubes
Handbook of Aluminum vol. 2: Alloy Production and Materials Manufacturing, George Totten and D. Scott MacKenzie (editors), 2003
ASTM B209: Standard Specification for Aluminum and Aluminum-Alloy Sheet and Plate
Aluminum Standards and Data, Aluminum Association Inc., 2013
ASM Specialty Handbook: Aluminum and Aluminum Alloys, J. R. Davis (editor), 1993
ISO 6361-2: Wrought aluminium and aluminium alloys - Sheets, strips and plates - Part 2: Mechanical properties
EN 573-3: Aluminium and aluminium alloys. Chemical composition and form of wrought products. Chemical composition and form of products