24 July 2021 7000 Series Aluminum Alloy
7050 Aluminum Alloy Plate
7050 aluminum alloy is a high-strength heat-treatable alloy with extremely high strength and resistance to spalling corrosion and stress corrosion cracking. Commonly used in aircraft structural parts for medium and thick plate extrusions, free forgings and die forgings. The main alloying element of 7050 series aluminum alloy is zinc. Adding magnesium to the alloy containing 3%-7.5% zinc can form MgZn2 with significant strengthening effect, making the heat treatment effect of this alloy far better than aluminum-zinc binary alloy.
7050 aluminium alloy is a heat-treatable alloy which is known as a commercial aerospace alloy. The alloy offers a combination of high strength, high fatigue strength and high resistance to stress corrosion cracking. Particularly suited to heavy plate applications, the material is used to build fuselage frames, wing skins and other aerospace structures. 7050 alloy is available in two tempers.
The content of zinc and magnesium in the steel, the tensile hardness will be further improved, and its resistance to stress corrosion and spalling corrosion will increase accordingly. After heat treatment, very high strength characteristics can be achieved. This series of materials generally will be added in a small amount Alloys such as copper and chromium. In this series, 7050-7451 aluminum alloy is the top grade. It is known as the best product among aluminum alloys. It has high strength and is far better than mild steel. This alloy has good mechanical properties and anode reactions. Mainly used Used in aerospace, mold processing, machinery and equipment. Tooling and fixtures, especially for aircraft manufacturing structures and other high-stress structures that require high strength and strong corrosion resistance.
Chemical Composition:
| Chemical Elements | Metric | English |
|---|---|---|
| Aluminum, Al | 87.3 - 90.3 % | 87.3 - 90.3 % |
| Chromium, Cr | <= 0.04 % | <= 0.04 % |
| Copper, Cu | 2.0 - 2.6 % | 2.0 - 2.6 % |
| Iron, Fe | <= 0.15 % | <= 0.15 % |
| Magnesium, Mg | 1.9 - 2.6 % | 1.9 - 2.6 % |
| Manganese, Mn | <= 0.10 % | <= 0.10 % |
| Other, each | <= 0.05 % | <= 0.05 % |
| Other, total | <= 0.15 % | <= 0.15 % |
| Silicon, Si | <= 0.12 % | <= 0.12 % |
| Titanium, Ti | <= 0.06 % | <= 0.06 % |
| Zinc, Zn | 5.7 - 6.7 % | 5.7 - 6.7 % |
| Zirconium, Zr | 0.08 - 0.15 % | 0.08 - 0.15 % |
Mechanical Properties:
| Mechanical Properties | Metric | English | Comments |
|---|---|---|---|
| Hardness, Brinell | 140 | 140 | 500 kg load with 10 mm ball. Calculated value. |
| Hardness, Knoop | 177 | 177 | Converted from Brinell Hardness Value |
| Hardness, Rockwell A | 51.6 | 51.6 | Converted from Brinell Hardness Value |
| Hardness, Rockwell B | 84 | 84 | Converted from Brinell Hardness Value |
| Hardness, Vickers | 162 | 162 | Converted from Brinell Hardness Value |
| Tensile Strength, Ultimate | 524 MPa | 76000 psi | AA; Typical |
| Tensile Strength, Yield | 469 MPa | 68000 psi | AA; Typical |
| Elongation at Break | 11 % @Diameter 12.7 mm | 11 % @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 | >= 22.0 MPa-m½ | >= 20.0 ksi-in½ | S-L |
| >= 24.2 MPa-m½ | >= 22.0 ksi-in½ | T-L | |
| >= 26.4 MPa-m½ | >= 24.0 ksi-in½ | L-T | |
| 28.0 MPa-m½ | 25.5 ksi-in½ | K(IC) in S-L Direction | |
| 28.6 MPa-m½ | 26.0 ksi-in½ | average; S-L | |
| 29.7 MPa-m½ | 27.0 ksi-in½ | average; T-L | |
| 31.0 MPa-m½ | 28.2 ksi-in½ | K(IC) in T-L Direction | |
| 35.0 MPa-m½ | 31.9 ksi-in½ | K(IC) in L-T Direction | |
| 35.2 MPa-m½ | 32.0 ksi-in½ | average; L-T | |
| Shear Modulus | 26.9 GPa | 3900 ksi | |
| Shear Strength | 303 MPa | 44000 psi | AA; Typical |
Thermal Properties:
| Thermal Properties | Metric | English | Comments |
|---|---|---|---|
| CTE, linear | 21.7 µm/m-°C @Temperature -50.0 - 20.0 °C | 12.1 µin/in-°F @Temperature -58.0 - 68.0 °F | |
| 23.0 µm/m-°C @Temperature 20.0 - 100 °C | 12.8 µin/in-°F @Temperature 68.0 - 212 °F | AA; Typical; average over range | |
| 23.5 µm/m-°C @Temperature 20.0 - 100 °C | 13.1 µin/in-°F @Temperature 68.0 - 212 °F | ||
| 24.4 µm/m-°C @Temperature 20.0 - 200 °C | 13.6 µin/in-°F @Temperature 68.0 - 392 °F | ||
| 25.4 µm/m-°C @Temperature 20.0 - 300 °C | 14.1 µin/in-°F @Temperature 68.0 - 572 °F | ||
| Specific Heat Capacity | 0.860 J/g-°C | 0.206 BTU/lb-°F | |
| Thermal Conductivity | 157 W/m-K | 1090 BTU-in/hr-ft²-°F | |
| Melting Point | 488 - 629.4 °C | 910 - 1165 °F | AA; Typical range based on typical composition for wrought products >= 1/4 in. thickness |
| Solidus | 488 °C | 910 °F | AA; Typical |
| Liquidus | 629.4 °C | 1165 °F | AA; Typical |
Process Properties:
| Processing Properties | Metric | English |
|---|---|---|
| Annealing Temperature | 413 °C | 775 °F |
| Solution Temperature | 477 °C | 890 °F |
| Aging Temperature | 121 - 177 °C | 250 - 350 °F |
Forming:
7050 aluminum alloy can be formed in O temper or heat treated conditions.
Welding:
7050 aluminum alloy should not be welded in order to prevent cracking and development of porosity. The weld joint produced will be weaker than the parent metal. Gas tungsten or gas metal arc welding methods are not preferred for welding this alloy.
Heat Treatment:
7050 aluminum alloy can be heat treated at 477°C (890°F). The time taken for this process is based upon the thickness of the section.
Cold Working:
7050 aluminum alloy can be cold worked using conventional methods.
Aging:
7050 aluminum alloy is aged using two-stage heat treatment. It is heated at 122°C (250°F) for 3 to 6 h. It is again heated at 163°C (325°F) for 15 h followed by cooling in air.
Hardening:
7050 aluminum alloy can be hardened by precipitation heat treatment.
Applications:
7050 aluminum alloy is mainly used in manufacturing aircraft and other structures.