24 July 2021 7000 Series Aluminum Alloy
7049 Aluminum Alloy Bar
7049 aluminum alloy (also known as UNS A97049) is primarily used as a forging alloy in the aerospace industry. Due to its excellent resistance to stress corrosion cracking, this alloy is often used in structural forgings. Forging should be done using hot forging/forming at temperatures between 720 F and 820 F. 7049 Aluminum is primarily aluminum based, with traces of zinc, magnesium, copper and chromium.
7049 aluminum is a 7000-series aluminum alloy: the main alloying addition is zinc and it is formulated for primary forming into wrought products. 7049 is the Aluminum Association (AA) designation for this material. In European standards, it will be given as EN AW-7049. Additionally, the AFNOR (French) designation is A-Z8GU. And the UNS number is A97049.
Chemical Composition:
| Chemical Elements | Metric | English | Comments |
|---|---|---|---|
| Aluminum, Al | 85.7 - 89.5 % | 85.7 - 89.5 % | As remainder |
| Chromium, Cr | 0.10 - 0.22 % | 0.10 - 0.22 % | |
| Copper, Cu | 1.2 - 1.9 % | 1.2 - 1.9 % | |
| Iron, Fe | <= 0.35 % | <= 0.35 % | |
| Magnesium, Mg | 2.0 - 2.9 % | 2.0 - 2.9 % | |
| Manganese, Mn | <= 0.20 % | <= 0.20 % | |
| Other, each | <= 0.05 % | <= 0.05 % | |
| Other, total | <= 0.15 % | <= 0.15 % | |
| Silicon, Si | <= 0.25 % | <= 0.25 % | |
| Titanium, Ti | <= 0.10 % | <= 0.10 % | |
| Zinc, Zn | 7.2 - 8.2 % | 7.2 - 8.2 % |
Mechanical Properties:
| Mechanical Properties | Metric | English | Comments |
|---|---|---|---|
| Hardness, Brinell | 135 | 135 | AA; Typical; 500 g load; 10 mm ball |
| Hardness, Knoop | 170 | 170 | Converted from Brinell Hardness Value |
| Hardness, Rockwell A | 50.5 | 50.5 | Converted from Brinell Hardness Value |
| Hardness, Rockwell B | 82 | 82 | Converted from Brinell Hardness Value |
| Hardness, Vickers | 155 | 155 | Converted from Brinell Hardness Value |
| Tensile Strength, Ultimate | 517 MPa | 75000 psi | AA; Typical |
| Tensile Strength, Yield | 448 MPa | 65000 psi | AA; Typical |
| Elongation at Break | 12 % @Diameter 12.7 mm | 12 % @Diameter 0.500 in | AA; Typical |
| Modulus of Elasticity | 71.7 GPa | 10400 ksi | AA; Typical; Average of tension and compression. Compression modulus is about 2% greater than tensile modulus. |
| Poissons Ratio | 0.33 | 0.33 | |
| Fracture Toughness | 24.0 MPa-m½ | 21.8 ksi-in½ | K(IC) in S-L Direction |
| 34.0 MPa-m½ | 30.9 ksi-in½ | K(IC) in L-S Direction | |
| 36.0 MPa-m½ | 32.8 ksi-in½ | K(IC) in L-T Direction | |
| Shear Modulus | 27.6 GPa | 4000 ksi | |
| Shear Strength | 303 MPa | 44000 psi | AA; Typical |
Thermal Properties:
| Thermal Properties | Metric | English | Comments |
|---|---|---|---|
| CTE, linear | 23.4 µm/m-°C @Temperature 20.0 - 100 °C | 13.0 µin/in-°F @Temperature 68.0 - 212 °F | AA; Typical; average over range |
| 25.0 µm/m-°C @Temperature 20.0 - 300 °C | 13.9 µin/in-°F @Temperature 68.0 - 572 °F | ||
| Specific Heat Capacity | 0.960 J/g-°C | 0.229 BTU/lb-°F | |
| Thermal Conductivity | 154 W/m-K | 1070 BTU-in/hr-ft²-°F | AA; Typical at 77°F |
| Melting Point | 477 - 635.0 °C | 890 - 1175 °F | AA; Typical range based on typical composition for wrought products >= 1/4 in. thickness |
| Solidus | 477 °C | 890 °F | AA; Typical |
| Liquidus | 635.0 °C | 1175 °F | AA; Typical |
Heat Treatment:
Solution heat treatment can be performed on the aluminium / aluminum 7049 alloy at 468°C (875°F) for a certain amount of time so as to ensure complete heating. This is then followed by a water quench. The 7049 alloy can be aged after the solution heat treatment
Forging:
The aluminium / aluminum 7049 alloy is forgeable from 438°C (820°F) down to 382°C (720°F).
Hot Working:
The aluminium / aluminum 7049 alloy can be hot worked from 438°C (820°F) down to 382°C (720°F).
Aging:
Aging or precipitation hardening can be carried out for the aluminium / aluminum 7049 alloy in a two-step heat treating process. The first step involves allowing the product to remain at room temperature, then for 24 hours at 121°C (250 °F), and finally air cooled. For the second step, a 14-h aging process at 160°C (320° F) is carried out followed by air cooling for 14 h.
Applications:
The aluminium / aluminum 7049 alloy is mainly used in structural forgings, especially in the missile or aircraft industries.