O (annealed)
Softest condition, used for drawing to finer sizes and for cold heading complex shapes. Parts are then solution treated and aged to reach strength.
Aerospace wire and drawn rod
7A09 Aerospace Aluminium Wire
7A09 is the Chinese-standard designation for a high-strength Al-Zn-Mg-Cu alloy whose chemistry sits almost on top of 7075. Drawn into wire and small rod, it is used for fastener blanks, pins, shafts and cold-headed parts where strength per kilogram matters more than weldability. Metline supplies 7A09 wire, or 7075 wire where Western certification is required, with full mill certification to customers worldwide.
- Alloy family
- 7xxx (Al-Zn-Mg-Cu)
- Tempers
- O, W/T4, T6, T73
- Diameter
- About 0.5 – 12 mm
- Nearest Western grade
- 7075
What is 7A09 aluminium wire?
7A09 belongs to the 7xxx series, where zinc and magnesium form fine MgZn2 precipitates during ageing. That precipitation is what gives 7xxx alloys the highest strength of any common wrought aluminium, roughly twice that of 6061 in the peak-aged condition.
The grade is registered in the Chinese wrought-alloy standard GB/T 3190 and was formerly known as LC9. Its zinc, magnesium, copper and chromium ranges overlap those of 7075 so closely that engineers usually treat the two as interchangeable for design purposes, although the impurity limits are not identical and the certifying standard must still match the drawing.
In wire and small-diameter drawn rod, 7A09 is chosen for parts that are machined, headed or rolled from bar stock and then aged: shear pins, hinge pins, solid rivet blanks for heavy joints, threaded studs, small shafts and spring-loaded clips. It is not a welding wire and should never be used as filler metal; 7xxx alloys of this type crack when fusion welded.
7A09 chemical composition compared with 7075 (wt %)
The table shows the generally published limits for 7A09 alongside the Aluminum Association limits for 7075. The overlap is clear; the main differences are slightly wider silicon and iron allowances and a marginally different chromium window in 7A09. Every delivery is certified with the actual analysis of the cast.
| Element | 7A09 (GB/T 3190) | 7075 (AA / EN AW-7075) | Role |
|---|---|---|---|
| Zinc (Zn) | 5.1 – 6.1 | 5.1 – 6.1 | Main strengthening element with Mg |
| Magnesium (Mg) | 2.0 – 3.0 | 2.1 – 2.9 | Forms MgZn2 precipitates |
| Copper (Cu) | 1.2 – 2.0 | 1.2 – 2.0 | Raises strength and improves stress-corrosion behaviour |
| Chromium (Cr) | 0.16 – 0.30 | 0.18 – 0.28 | Controls grain structure, reduces SCC susceptibility |
| Silicon (Si), max | 0.50 | 0.40 | Impurity |
| Iron (Fe), max | 0.50 | 0.50 | Impurity; affects toughness |
| Manganese (Mn), max | 0.15 | 0.30 | Impurity / grain control |
| Titanium (Ti), max | 0.10 | 0.20 | Grain refiner |
| Aluminium (Al) | Remainder | Remainder |
7A09 limits are as commonly published from GB/T 3190; confirm the revision on your drawing. The figures on an earlier version of this page (zinc 2.4 – 2.8 %) did not match the standard and have been corrected.
7A09 tempers and what each is for
W / "T4" (freshly quenched)
7xxx alloys keep hardening at room temperature for months after quenching, so a true stable T4 does not exist. Wire described as T4 is solution treated and quenched, and must be formed or driven quickly, or held refrigerated, before it hardens.
T6
Solution treated and artificially aged to peak strength. Used for pins, shafts and machined parts that see high static loads in benign environments.
T73
Over-aged. Strength drops by roughly 10 – 15 % compared with T6, but resistance to stress-corrosion cracking and exfoliation improves sharply. The usual choice for fasteners in airframes.
T74 / T76
Intermediate over-aged conditions that trade a little less strength than T73 for better resistance than T6. Specified on some drawings for rod and forging stock.
H13 / F
Drawn or as-fabricated conditions with no guaranteed properties, used as feedstock for the customer's own heat treatment.
Mechanical and physical properties
Because 7A09 and 7075 share their chemistry, published typical values for 7075 wire and rod are a sound guide. Design values must come from the specification on the order; the table below is for comparison only.
| Temper | Tensile strength (typical) | Yield strength (typical) | Elongation | Shear strength |
|---|---|---|---|---|
| O | 220 – 230 MPa | 95 – 105 MPa | 15 – 17 % | About 150 MPa |
| T6 | 540 – 570 MPa | 470 – 505 MPa | 8 – 11 % | About 330 MPa |
| T73 | 490 – 505 MPa | 420 – 435 MPa | 10 – 13 % | About 300 MPa |
Physical properties
- Density
- About 2.80 – 2.81 g/cm³
- Modulus of elasticity
- About 71 – 72 GPa
- Melting range
- About 475 – 635 °C
- Thermal conductivity
- About 130 W/m·K (T6), higher in T73
- Electrical conductivity
- About 33 % IACS (T6), 38 – 40 % IACS (T73)
- Thermal expansion
- About 23.4 µm/m·°C (20 – 100 °C)
Electrical conductivity is often used to confirm the temper of 7xxx parts: over-aged tempers read noticeably higher than T6.
An older version of this page described 7A09 wire as having "good electrical conductivity" for power transmission. That is misleading: at about a third of the conductivity of pure aluminium, 7xxx wire is a structural material. For conductors, use 1350, 1370 or 6101 wire.
Sizes, forms and standards
Supply range
- Diameter
- About 0.5 – 12 mm wire; larger sizes supplied as drawn or extruded rod
- Form
- Coils, spools or straightened and cut lengths
- Tolerance
- Drawn to h9 – h11 or to the fastener maker's diameter tolerance on request
- Surface
- Bright drawn, free of laps and seams; optional eddy-current inspection
- Chemistry standard
- GB/T 3190 (7A09); AA registration / EN 573-3 when ordered as 7075
- Product standards
- ASTM B211 and AMS 4122 (7075 bar, rod and wire); AMS-QQ-A-430 rivet wire where specified
| System | Designation | Notes |
|---|---|---|
| China (GB) | 7A09 (formerly LC9) | Wrought chemistry per GB/T 3190 |
| Aluminum Association | 7075 (nearest) | Close chemical equivalent |
| UNS | A97075 (for 7075) | |
| Europe (EN) | EN AW-7075 / AlZn5.5MgCu | EN 573-3 |
| Russia (GOST) | V95 (nearest) | Similar Al-Zn-Mg-Cu family |
Heading, machining and finishing
Cold heading
Head in O or freshly quenched condition, then age. Heading in T6 risks cracking at the head-shank fillet.
Machining
Excellent in T6 and T73: short chips and a fine finish on Swiss-type and automatic lathes.
Heat treatment
Solution treatment at about 465 – 480 °C followed by fast water quench; ageing schedules follow AMS 2770 practice for 7075.
Joining
Not fusion weldable. Riveting, bolting and adhesive bonding are standard.
Corrosion protection
Anodise (sulphuric or chromic acid) or apply conversion coatings; specify T73 for parts exposed to sustained tensile stress.
Inspection
Diameter, surface and conductivity checks; tensile and shear tests on samples from each lot.
Where 7A09 wire is used
- Airframe fasteners: blanks for pins, bolts and studs that are headed, rolled and aged
- Hinge and shear pins: control-surface hinges, access panels and quick-release fittings
- Small shafts and spindles: actuator parts, instrument mechanisms and drone frames
- Clips and retaining rings: formed in soft temper and then aged
- Sports and defence: lightweight high-strength pins, arrow shafts and fixings
Older material for this grade listed uses in "circuit systems" and power transmission; these are not realistic for a 7xxx alloy and have been removed.
7A09 compared with other fastener wires
| Property | 7A09 / 7075-T73 | 2024-T4 | 2117-T4 | 7050-T73 |
|---|---|---|---|---|
| Typical tensile strength | ~500 MPa | ~470 MPa | ~300 MPa | ~500 – 510 MPa |
| Typical shear strength | ~300 MPa | ~280 MPa | ~195 MPa | ~300 MPa |
| Drivable as rivet after ageing | No | Ice-box only | Yes | Yes (special) |
| SCC resistance | Good in T73 | Fair | Good | Good |
2117-T4 is the standard "AD" rivet wire because it can be driven in the aged condition. 2024 and 7xxx alloys give higher shear strength but need either ice-box handling or a pin-and-collar fastener design.
How to order 7A09 wire
- SpecifyAlloy and temper, diameter and tolerance, coil or cut length, quantity and the governing specification with its revision (GB/T 3190, ASTM B211, AMS 4122).
- ConfirmWe confirm the specification can be met, the tolerance class, any extra tests and the delivery terms (EXW, FOB, CIF or DAP).
- InspectMaterial is checked for dimensions, straightness and surface condition; tests named on the order are carried out or arranged with a third party.
- DocumentEach lot ships with a mill test certificate to EN 10204 3.1 showing chemistry and mechanical results, traceable to the cast or lot number.
- Pack and shipExport packing in sealed, moisture-protected wooden cases, coils on pallets or reels, shipped by sea or air to your port or door.
References and standards
- GB/T 3190 – Wrought aluminium and aluminium alloys: chemical composition
- ASTM B211 – Aluminum and Aluminum-Alloy Rolled or Cold-Finished Bar, Rod, and Wire
- SAE AMS 4122 – Aluminum Alloy Bars, Rods, and Wire, Rolled or Cold Finished (7075-T6, T651)
- SAE AMS 2770 – Heat Treatment of Wrought Aluminum Alloy Parts
- The Aluminum Association – International Alloy Designations and Chemical Composition Limits (Teal Sheets)
7A09 aluminium (aluminum) wire: frequently asked questions
Is 7A09 the same as 7075?
Chemically they are very close and are treated as equivalents for most designs. They are certified to different standards, so if your drawing calls for 7075 to ASTM or AMS, order and certify it as 7075.
Can 7A09 wire be used for welding?
No. Al-Zn-Mg-Cu alloys with copper crack when fusion welded and are not used as filler metal. For welding wire, see ER4043, ER5356 or ER5183.
Which temper should I specify for fasteners?
T73 for most airframe fasteners, because it resists stress-corrosion cracking. T6 gives more strength but should be limited to parts with low sustained tensile stress or a benign environment.
Why is "T4" 7A09 wire unstable?
7xxx alloys continue to age at room temperature after quenching, so their properties drift for months. That condition is properly called W; parts must be formed quickly or kept refrigerated.
What diameters can you supply?
Wire from about 0.5 to 12 mm, with larger sizes as drawn or extruded rod. Straight cut lengths or coils are available.
Do you ship internationally?
Yes. Metline ships worldwide from Mumbai with EN 10204 3.1 certificates and export packing.
Need 7A09 or 7075 wire?
Tell us the diameter, temper, form and specification. We will confirm availability and certification.
