7050-T76511
Least overaged. Highest strength of the three with good exfoliation resistance. Common for stiffeners and parts loaded mainly along the bar axis.
Aerospace · thick-section 7xxx bar
7050 Aerospace Aluminium Bar & Rod
7050 bar and rod give aerospace machinists high strength, good fracture toughness and strong resistance to stress-corrosion cracking, and they keep those properties in large diameters where 7075 falls off. Extruded 7050 bar is ordered in T76511 (AMS 4340), T73511 (AMS 4341) or T74511 (AMS 4342), with forged bar for the largest sections. Metline supplies round, square and rectangular 7050 bar, cut to length and fully certified, to buyers worldwide.
- Alloy
- 7050 (Al-Zn-Cu-Mg-Zr)
- Tempers
- T73511, T74511, T76511, T7452
- Shapes
- Round, square, rectangular, forged bar
- Standards
- AMS 4340 · 4341 · 4342 · ASTM B221
Why 7050 bar is specified for aerospace parts
7050 was developed to solve a problem with 7075: thick 7075 sections lose strength in the centre because they cool too slowly during quenching, and in the peak-aged T6 temper they are prone to stress-corrosion cracking. 7050 replaces chromium with zirconium and raises copper, which lowers quench sensitivity and lets the alloy be overaged for corrosion resistance with little loss of strength.
The result is a bar that machines into fittings, lugs, actuator housings, landing-gear components and fasteners with strength close to 7075-T6, better toughness, and much better resistance to stress corrosion. Low iron and silicon limits reduce the coarse particles that start fatigue cracks, which is why 7050 is a default choice for parts with long fatigue lives.
Because it holds properties through the section, 7050 is especially valued in large diameters. A 150 mm 7050-T74511 bar keeps far more of its strength at the core than a 7075-T6 bar of the same size, and it can be machined heavily without the distortion and cracking risks associated with peak-aged material.
7050 chemical composition (wt %)
These are the registered Aluminum Association limits used by the AMS bar specifications, ASTM B221 and EN 573-3 (EN AW-7050, AlZn6CuMgZr). Each lot certificate reports the actual cast analysis.
| Element | Minimum | Maximum | Role in the alloy |
|---|---|---|---|
| Silicon (Si) | — | 0.12 | Held very low for fracture toughness |
| Iron (Fe) | — | 0.15 | Held very low; fewer coarse intermetallics |
| Copper (Cu) | 2.0 | 2.6 | Raises strength and stress-corrosion resistance in T7 tempers |
| Manganese (Mn) | — | 0.10 | Residual |
| Magnesium (Mg) | 1.9 | 2.6 | Forms MgZn2 with zinc |
| Chromium (Cr) | — | 0.04 | Deliberately low; zirconium replaces it |
| Zinc (Zn) | 5.7 | 6.7 | Main strengthening element |
| Titanium (Ti) | — | 0.06 | Grain refiner |
| Zirconium (Zr) | 0.08 | 0.15 | Controls grain structure and lowers quench sensitivity |
| Others, each / total | — | 0.05 / 0.15 | |
| Aluminium (Al) | Remainder | About 87.3 – 90.3 % |
7050 bar properties by temper
The table gives approximate typical values for extruded bar in the middle of the size range. Minimum values in AMS 4340, 4341 and 4342 are lower, depend on diameter or thickness and test direction, and are what the design must use. Your mill certificate shows the actual results against those minimums.
| Temper (specification) | Tensile strength (typical) | Yield strength (typical) | Elongation (typical) | Typical use |
|---|---|---|---|---|
| T76511 (AMS 4340) | About 550 MPa / 80 ksi | About 490 MPa / 71 ksi | About 9 – 11 % | Highest strength, good exfoliation resistance |
| T74511 (AMS 4342) | About 515 MPa / 75 ksi | About 455 MPa / 66 ksi | About 10 – 12 % | Balanced strength and stress-corrosion resistance |
| T73511 (AMS 4341) | About 495 MPa / 72 ksi | About 435 MPa / 63 ksi | About 10 – 12 % | Maximum stress-corrosion resistance |
| T7452 forged bar (AMS 4108) | About 490 – 510 MPa | About 420 – 440 MPa | About 9 – 12 % | Very large sections; compressed for stress relief |
Electrical conductivity is measured on overaged 7xxx tempers as a quick check that the ageing treatment has reached the required level; the acceptance range is set by the specification.
Physical properties
- Density
- 2.83 g/cm³ (0.102 lb/in³)
- Modulus of elasticity (tension)
- About 71.7 GPa (10,400 ksi)
- Shear modulus
- About 26.9 GPa
- Thermal conductivity
- About 155 – 160 W/m·K (T74 tempers)
- Electrical conductivity
- About 39 – 44 % IACS (T74 / T76), used as a check on the overaged temper
- Coefficient of thermal expansion
- About 23.5 µm/m·°C (20 – 100 °C)
- Melting range
- About 490 – 630 °C
Which 7050 bar temper to order
All three extruded tempers are solution heat-treated, stretched to relieve residual stress (51), straightened (1) and overaged. The digit after the 7 shows how far the ageing goes.
7050-T74511
The middle path, and the most widely ordered. Used for fittings, links and machined parts where short-transverse stress corrosion is a design concern.
7050-T73511
Most overaged. Best resistance to stress-corrosion cracking, used where parts see sustained tensile stress across the grain in a damp environment.
7050-T7452
Forged bar and hand forgings, compressed rather than stretched after quenching. Covers sections too large to extrude.
7050 bar specifications and designations
| System | Designation / standard | Scope |
|---|---|---|
| SAE AMS | AMS 4340 | 7050-T76511 extruded bar, rod, wire, profiles and tube up to 5 in (127 mm) |
| SAE AMS | AMS 4341 | 7050-T73511 extrusions |
| SAE AMS | AMS 4342 | 7050-T74511 extrusions |
| SAE AMS | AMS 4108 | 7050-T7452 hand forgings (forged bar and blocks) |
| ASTM | ASTM B221 | Extruded bar, rod, wire, profiles and tube |
| Inspection | AMS-STD-2154 / ASTM B594 | Ultrasonic inspection of wrought products |
| UNS | A97050 | — |
| European | EN AW-7050 (AlZn6CuMgZr) | EN 573-3, EN 755-2 |
| German Werkstoff | 3.4144 | — |
| Japan | A7050 | JIS H4040 / H4100 |
Aircraft manufacturers also publish their own material specifications that call up 7050 bar with extra requirements. Quote these on the enquiry so the material can be certified against them.
7050 bar sizes and weights
Supply range
- Extruded round bar
- About 10 mm to 127 mm (5 in) under the AMS extrusion specifications; larger extruded rounds by enquiry
- Square and rectangular bar
- Squares about 25 – 125 mm; rectangles to about 300 mm wide
- Forged bar
- Large rounds and rectangles beyond extrusion limits, to AMS 4108 (T7452)
- Lengths
- Mill lengths such as 12 ft (3.66 m) or cut pieces to your list
- Imperial sizes
- Common rounds 1 – 6 in; rectangles such as 2 × 1.2 in up to 6 × 3 in
Large diameters are usually supplied as forged bar or as extrusions from large presses. Tell us the finished part size and we will suggest the most economical stock.
Weight of 7050 round bar per metre is π/4 × d² × 2.83 ÷ 1000 kg (d in mm). 7050 is about 5 % heavier than 6061 because of its zinc and copper content.
| Diameter (mm) | kg per metre | kg per 3 m bar | Diameter (in) |
|---|---|---|---|
| 20 | 0.889 | 2.67 | 0.79 |
| 25 | 1.389 | 4.17 | 0.98 |
| 30 | 2.000 | 6.00 | 1.18 |
| 40 | 3.556 | 10.67 | 1.57 |
| 50 | 5.557 | 16.67 | 1.97 |
| 60 | 8.002 | 24.00 | 2.36 |
| 70 | 10.891 | 32.67 | 2.76 |
| 80 | 14.225 | 42.68 | 3.15 |
| 100 | 22.227 | 66.68 | 3.94 |
| 120 | 32.007 | 96.02 | 4.72 |
| 127 | 35.850 | 107.55 | 5.00 |
| 150 | 50.010 | 150.03 | 5.91 |
| 200 | 88.907 | 266.72 | 7.87 |
| 250 | 138.917 | 416.75 | 9.84 |
| 300 | 200.041 | 600.12 | 11.81 |
Tolerances, testing and certification
Typical inspection for aerospace orders
- Dimensions and straightness
- To ANSI H35.2 tolerances for extruded bar unless the order specifies tighter limits
- Tensile testing
- Longitudinal (and transverse where required) tests per lot to the AMS specification
- Conductivity
- Eddy-current conductivity check on overaged tempers
- Ultrasonic
- Immersion or contact testing to AMS-STD-2154 or ASTM B594, class as ordered
- Certification
- EN 10204 3.1 certificate with cast analysis and test results; traceable by lot
Machining and joining 7050 bar
Machining
Machines very well with short chips and a fine finish. Use sharp carbide, high spindle speeds and flood coolant. Stretched tempers keep residual stress low, so long slender parts stay straight.
Joining
Not recommended for arc welding (MIG or TIG): the alloy is crack-prone and loses strength in the heat-affected zone. Parts are bolted, riveted or bonded; friction stir welding is used in some structures.
Forming
Limited cold formability in the overaged tempers. Form complex shapes before final heat treatment or machine them from solid.
Finishing
Responds well to chromic, sulphuric and boric-sulphuric anodising and to conversion coatings followed by primer.
What 7050 bar is machined into
- Airframe fittings: wing-to-fuselage fittings, lugs, clevises and brackets
- Landing gear and actuation: links, torque arms, actuator bodies and end fittings
- Fasteners: high-strength rivets, pins and collars, often from drawn wire and rod
- Helicopters: rotor-head and transmission-support parts
- Space and defence: launch-vehicle fittings, missile structures and precision mounts
- Motorsport and high-end engineering: suspension uprights and highly stressed brackets
7050 bar compared with 7075 and 2024
| Property | 7050-T74511 | 7075-T6511 | 7075-T73511 | 2024-T3511 |
|---|---|---|---|---|
| Typical tensile strength | About 515 MPa | About 570 MPa | About 500 MPa | About 485 MPa |
| Strength retention in thick sections | Very good | Falls with size | Falls with size | Moderate |
| Stress-corrosion resistance | Good–very good | Poor in short-transverse direction | Very good | Fair |
| Fracture toughness | Good | Moderate | Moderate | Good |
| Relative cost | High | Medium | Medium–high | Medium |
In small diameters, 7075-T6 is often cheaper and strong enough. For bar above about 75 mm, or where stress corrosion is a concern, 7050 is the better material. See our 7050 versus 7075 comparison for more detail.
How to order 7050 aerospace bar
- SpecifyAlloy and temper, shape and size, length or cut pieces, quantity and the governing specification with its revision (AMS 4340, AMS 4341, AMS 4342, AMS 4108 or ASTM 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 4340 – Aluminum Alloy Extrusions, 7050-T76511
- SAE AMS 4342 – Aluminum Alloy Extrusions, 7050-T74511
- SAE AMS 4108 – Aluminum Alloy Hand Forgings, 7050-T7452
- ASTM B221 – Standard Specification for Aluminum and Aluminum-Alloy Extruded Bars, Rods, Wire, Profiles, and Tubes
- ASTM B594 – Standard Practice for Ultrasonic Inspection of Aluminum-Alloy Wrought Products
- The Aluminum Association – International Alloy Designations and Chemical Composition Limits (Teal Sheets)
7050 aerospace aluminium (aluminum) bar: FAQ
Which 7050 bar temper is most common?
T74511 (AMS 4342) is the most widely ordered because it balances strength and stress-corrosion resistance. T76511 is chosen for higher strength and T73511 for maximum stress-corrosion resistance.
Why choose 7050 bar instead of 7075?
7050 keeps its strength in thick sections, has better fracture toughness and resists stress corrosion in overaged tempers. For large diameters and fatigue-critical fittings it usually outperforms 7075.
Can 7050 bar be welded?
Not by MIG or TIG; the weld zone cracks and loses strength. Use mechanical fastening or bonding. Friction stir welding is possible but must be qualified for the application.
What is the largest 7050 bar available?
The AMS extrusion specifications cover sections up to 5 in (127 mm). Larger rounds and rectangles are usually supplied as forged bar to AMS 4108 in the T7452 temper.
How much does a 7050 bar weigh?
A 50 mm round weighs about 5.56 kg per metre and a 100 mm round about 22.2 kg per metre, based on a density of 2.83 g/cm³.
Do you supply 7050 bar with ultrasonic test reports?
Yes. Ultrasonic inspection to AMS-STD-2154 or ASTM B594 at the class you specify can be supplied, along with the EN 10204 3.1 certificate.
Need 7050 bar or rod?
Send the temper, size, length, specification and destination. We will reply with availability, certification and a delivered price.
