Machining
Among the easiest aluminium alloys to machine in T6 and T651. Use carbide or HSS with positive rake, high speeds and coolant. T651 stays straight on long turned parts.
Aerospace · high-strength bar stock
7075 Aerospace Aluminium Bar & Rod
7075 bar is the classic high-strength aerospace machining stock: in T6 and T651 it reaches about 570 MPa tensile strength, close to many steels at about a third of the weight. For parts that need resistance to stress-corrosion cracking, the T7351 temper trades some strength for durability. Metline supplies 7075 round, square, hex and flat bar in T6, T651, T7351, T6511 and O tempers, certified to AMS, ASTM and EN standards, to customers worldwide.
- Alloy
- 7075 (Al-Zn-Mg-Cu-Cr)
- Tempers
- T6, T651, T7351, T6511, O
- Diameter
- About 5 – 250 mm
- Standards
- AMS 4122 · 4123 · 4124 · ASTM B211
Why 7075 bar is used in aircraft
7075 was introduced in the early 1940s as a high-zinc aluminium alloy and became the standard high-strength aircraft alloy. Zinc and magnesium form fine MgZn2 precipitates during ageing, copper adds strength, and chromium controls grain structure and improves resistance to stress-corrosion cracking.
In bar form, 7075 is machined into fittings, brackets, shafts, pins, actuator parts, gears and fasteners. It machines beautifully, giving short chips and a bright finish, which makes it a favourite for CNC turning and milling. The main limitations are poor weldability and, in the peak-aged T6 tempers, sensitivity to stress-corrosion cracking when loaded across the grain in damp environments.
The T73 tempers solve the corrosion problem: 7075-T7351 bar has much better stress-corrosion resistance at about 10 – 15 % lower strength. For larger diameters, or where both high strength and corrosion resistance are needed, designers increasingly move to 7050 bar, which holds its properties better in thick sections.
7075 chemical composition (wt %)
Registered Aluminum Association limits, used by AMS, ASTM B211 and B221 and EN 573-3 (EN AW-7075, AlZn5.5MgCu). The certificate shows the actual analysis of each cast.
| Element | Minimum | Maximum | Role in the alloy |
|---|---|---|---|
| Silicon (Si) | — | 0.40 | Impurity |
| Iron (Fe) | — | 0.50 | Impurity |
| Copper (Cu) | 1.2 | 2.0 | Adds strength; improves stress-corrosion resistance in T73 |
| Manganese (Mn) | — | 0.30 | Residual |
| Magnesium (Mg) | 2.1 | 2.9 | Forms MgZn2 with zinc |
| Chromium (Cr) | 0.18 | 0.28 | Grain control; resists recrystallisation and stress corrosion |
| Zinc (Zn) | 5.1 | 6.1 | Main strengthening element |
| Titanium (Ti) | — | 0.20 | Grain refiner |
| Others, each / total | — | 0.05 / 0.15 | |
| Aluminium (Al) | Remainder | About 87.1 – 91.4 % |
7075 bar properties by temper
Typical values are shown. Specified minimums in ASTM B211, B221 and the AMS documents are lower and vary with diameter or thickness, so the mill certificate is the reference for each lot.
| Temper | Tensile strength (typical) | Yield strength (typical) | Elongation | Hardness |
|---|---|---|---|---|
| O (annealed) | 228 MPa / 33 ksi | 103 MPa / 15 ksi | About 16 % | 60 HB |
| T6 / T651 | 572 MPa / 83 ksi | 503 MPa / 73 ksi | About 11 % | 150 HB |
| T6511 (extruded) | About 570 MPa | About 500 MPa | About 10 % | 150 HB |
| T73 / T7351 | 505 MPa / 73 ksi | 435 MPa / 63 ksi | About 13 % | 135 HB |
Some tables show 7075-T7351 with the same strength as T6, or 7075-O with a tensile strength above 300 MPa. Both are incorrect.
Physical properties
- Density
- 2.81 g/cm³ (0.101 lb/in³)
- Modulus of elasticity (tension)
- About 71.7 GPa (10,400 ksi)
- Shear strength (T6)
- About 330 MPa (48 ksi)
- Fatigue strength (T6, 5×10⁸ cycles, R.R. Moore)
- About 160 MPa (23 ksi)
- Thermal conductivity
- About 130 W/m·K (T6); about 155 W/m·K (T73)
- Electrical conductivity
- About 33 % IACS (T6); about 40 % IACS (T73)
- Coefficient of thermal expansion
- About 23.4 µm/m·°C (20 – 100 °C)
- Melting range
- About 477 – 635 °C
7075 bar tempers and the AMS specifications that cover them
| Temper | Common specification | Description | Typical use |
|---|---|---|---|
| T6 | AMS 4122, ASTM B211 | Rolled or cold-finished bar, solution treated and aged | Small fittings, pins, shafts |
| T651 | AMS 4123, ASTM B211 | As T6, stretched to relieve stress | Machined parts that must stay straight |
| T7351 | AMS 4124, ASTM B211 | Stretched and overaged for stress-corrosion resistance | Fittings loaded across the grain, wet areas |
| T6510 / T6511 | AMS 4154, ASTM B221 | Extruded bar, stretched (and straightened for 6511) | Larger and shaped bar stock |
| F / O | AMS 4186 | As fabricated or annealed bar, rod and wire | Material for later forming or heat treatment |
Older drawings may call the cancelled federal specification QQ-A-225/9, now covered by AMS-QQ-A-225/9 and the AMS numbers above. Quote the document and revision on your drawing so the bar is certified correctly.
7075 international designations
| System | Designation |
|---|---|
| UNS | A97075 |
| European | EN AW-7075 (AlZn5.5MgCu), EN 754 / EN 755 |
| German Werkstoff | 3.4365 |
| ISO | AlZn5.5MgCu |
| Japan | A7075 (JIS H4040) |
| China | 7075 (GB/T 3191); 7A09 is a close relative |
7075 bar sizes and weights
Supply range
- Round bar
- About 5 mm to 250 mm diameter; imperial 3/16 in to 10 in
- Square bar
- About 10 × 10 mm to 100 × 100 mm
- Hex bar
- About 12 – 65 mm across flats
- Flat bar
- Thickness about 3 – 100 mm, widths to about 300 mm
- Lengths
- 3 m or 12 ft mill lengths, random lengths, or cut pieces
- Finish
- Cold-finished, extruded, or turned and precision ground on request
Weight of 7075 round bar per metre is π/4 × d² × 2.81 ÷ 1000 kg (d in mm). Use the bar weight calculator for squares, hexes and flats.
| Diameter (mm) | kg per metre | kg per 3 m bar | Diameter (in) |
|---|---|---|---|
| 6 | 0.079 | 0.24 | 0.24 |
| 10 | 0.221 | 0.66 | 0.39 |
| 12 | 0.318 | 0.95 | 0.47 |
| 16 | 0.565 | 1.69 | 0.63 |
| 20 | 0.883 | 2.65 | 0.79 |
| 25 | 1.379 | 4.14 | 0.98 |
| 30 | 1.986 | 5.96 | 1.18 |
| 40 | 3.531 | 10.59 | 1.57 |
| 50 | 5.517 | 16.55 | 1.97 |
| 60 | 7.945 | 23.84 | 2.36 |
| 80 | 14.125 | 42.37 | 3.15 |
| 100 | 22.070 | 66.21 | 3.94 |
| 120 | 31.780 | 95.34 | 4.72 |
| 150 | 49.657 | 148.97 | 5.91 |
| 200 | 88.279 | 264.84 | 7.87 |
| 250 | 137.936 | 413.81 | 9.84 |
Machining, joining and finishing 7075 bar
Joining
Not suitable for MIG or TIG welding because of hot cracking and heat-affected zone softening. Use threaded joints, rivets, pins or bonding.
Forming
Poor cold formability in T6. Form in O or freshly quenched condition and then age.
Anodising
Anodises well; hard anodising is common on wear surfaces. Machined faces give the most even colour.
Corrosion
Protect with anodising or conversion coating and primer. Specify T7351 for parts under sustained stress in damp conditions.
Temperature
Strength falls with long exposure above about 120 °C. Not suitable for hot engine zones.
Typical uses of 7075 aerospace bar
- Airframe fittings: brackets, clevises, lugs and attachment fittings
- Actuation and landing gear: rods, pistons, end fittings and links
- Fasteners: bolts, pins and collars, plus 7075 rivet wire
- Seating and interiors: seat legs, track fittings and structural inserts
- Space and defence: satellite brackets, payload adaptors and missile parts
- Ground support and tooling: jigs, fixtures and high-strength tooling parts
7075 bar compared with 7050, 2024 and 6061
| Property | 7075-T651 | 7075-T7351 | 7050-T74511 | 2024-T351 | 6061-T6 |
|---|---|---|---|---|---|
| Typical tensile strength | 572 MPa | 505 MPa | About 515 MPa | 470 MPa | 310 MPa |
| Stress-corrosion resistance | Poor (short transverse) | Very good | Good–very good | Fair | Very good |
| Machinability | Excellent | Excellent | Excellent | Very good | Very good |
| Weldability | Poor | Poor | Poor | Poor | Good |
| Relative cost | Medium | Medium–high | High | Medium | Low |
For a full comparison see 6061 versus 7075 and 2024 versus 7075.
How to order 7075 aerospace bar
- SpecifyAlloy and temper, shape and size, length or cut pieces, quantity and the governing specification with its revision (AMS 4122, AMS 4123, AMS 4124, AMS 4154, ASTM B211 or B221).
- ConfirmWe confirm the specification can be met, the tolerance class, any extra tests (ultrasonic class, conductivity, fracture toughness) and the delivery terms (EXW, FOB, CIF or DAP).
- InspectMaterial is checked for dimensions, straightness or flatness and surface condition; tests named on the order are carried out or arranged with an independent laboratory.
- DocumentEach lot ships with a mill test certificate to EN 10204 3.1 showing chemistry, tensile results and conductivity where specified, traceable to the cast and lot number.
- Pack and shipExport packing in sealed, moisture-protected wooden cases or on pallets, with interleaving where surfaces are critical, shipped by sea or air to your port or door.
References and standards
- SAE AMS 4123 – Aluminum Alloy Bars and Rods, Rolled or Cold Finished, 7075-T651
- SAE AMS 4186 – Aluminum Alloy Bars, Rods and Wire, 7075-F / O
- ASTM B211 – Standard Specification for Aluminum and Aluminum-Alloy Rolled or Cold-Finished Bar, Rod, and Wire
- ASTM B221 – Standard Specification for Aluminum and Aluminum-Alloy Extruded Bars, Rods, Wire, Profiles, and Tubes
- The Aluminum Association – International Alloy Designations and Chemical Composition Limits (Teal Sheets)
- ASM Handbook, Vol. 2 – Properties and Selection: Nonferrous Alloys and Special-Purpose Materials
7075 aerospace aluminium (aluminum) bar: FAQ
What is the difference between 7075-T6 and T651 bar?
Strength is the same. T651 bar has been stretched after quenching to relieve internal stress, so it stays straighter when machined. Order T651 for long or heavily machined parts.
When should I use 7075-T7351 instead of T6?
Use T7351 when the part carries sustained stress across the grain or sits in a damp environment. It has far better stress-corrosion resistance at about 10 – 15 % lower strength.
Which AMS specification covers 7075 bar?
AMS 4122 covers T6, AMS 4123 covers T651 and AMS 4124 covers T7351 rolled or cold-finished bar. AMS 4154 covers extruded bar in T6, T6510 and T6511.
Can 7075 bar be welded?
Not by MIG or TIG; it cracks and loses strength. Join it mechanically or by bonding.
How much does a 7075 round bar weigh?
At a density of 2.81 g/cm³, a 25 mm bar weighs about 1.38 kg per metre and a 100 mm bar about 22.1 kg per metre.
Need 7075 bar or rod?
Send the temper, size, length, specification and destination. Our team will reply with availability, certification and a delivered price.
