T6
Solution treated and artificially aged for peak strength. General-purpose machining bar.
Aerospace · GB equivalent of 7075
7A09 Aerospace Aluminium Bar
7A09 (formerly LC9) is the Chinese GB grade whose chemistry overlaps 7075 almost exactly, and it is supplied as round, square and flat bar for aircraft fittings, frames and machined parts. Metline supplies 7A09 bar in T6, T651 and T6511 to GB/T 3191, and 7075 bar to AMS 4122, AMS 4124 or ASTM B211/B221 where a Western certificate is needed, to customers worldwide.
- Alloy
- 7A09 (LC9) ≈ 7075
- Tempers
- O, T6, T651, T6511, T73
- Diameter
- About 6 – 300 mm
- Standard
- GB/T 3191 · GB/T 3190
What 7A09 is and how it relates to 7075
7A09 was introduced in China as LC9 to match the performance of 7075. Its composition limits sit inside or very close to the 7075 ranges: zinc 5.1 – 6.1 %, magnesium 2.0 – 3.0 %, copper 1.2 – 2.0 % and chromium 0.16 – 0.30 %. In practice 7A09-T6 and 7075-T6 behave almost identically.
7A09 bar is used for aircraft fittings, frames and beams, landing-gear and control-system parts, and high-strength machined components in defence and industrial equipment. It is also forged and rolled into plate, but bar is the most common form outside China.
Where a drawing calls for 7A09, it can be supplied directly. Where the customer requires a UNS-registered alloy or an AMS certificate, 7075 bar is the usual alternative. Equivalence of chemistry is not the same as approval, so any substitution on aerospace hardware needs the design authority to agree.
| Grade | Former Chinese name | Nearest international grade | Comment |
|---|---|---|---|
| 7A04 | LC4 | 7075 (close, not identical) | Higher Mn, wider Zn range; related to the Russian V95 family |
| 7B04 | — | 7475 concept (high purity) | Low Fe and Si for toughness, mainly sheet, plate and wire |
| 7A09 | LC9 | 7075 | Chemistry overlaps 7075 almost completely |
| 7A03 | LC3 | 7050-type rivet use | Rivet wire alloy |
7A09 chemical composition compared with 7075 (wt %)
| Element | 7A09 | 7075 |
|---|---|---|
| Silicon (Si) | ≤ 0.50 | ≤ 0.40 |
| Iron (Fe) | ≤ 0.50 | ≤ 0.50 |
| Copper (Cu) | 1.2 – 2.0 | 1.2 – 2.0 |
| Manganese (Mn) | ≤ 0.15 | ≤ 0.30 |
| Magnesium (Mg) | 2.0 – 3.0 | 2.1 – 2.9 |
| Chromium (Cr) | 0.16 – 0.30 | 0.18 – 0.28 |
| Zinc (Zn) | 5.1 – 6.1 | 5.1 – 6.1 |
| Titanium (Ti) | ≤ 0.10 | ≤ 0.20 |
| Others, each / total | 0.05 / 0.15 | 0.05 / 0.15 |
| Aluminium (Al) | Remainder | Remainder |
A 7A09 cast that also falls within the 7075 limits (silicon ≤ 0.40 %, magnesium 2.1 – 2.9 %, chromium 0.18 – 0.28 %) can be certified to both grades. Ask for dual certification at the enquiry stage if you need it.
Limits as published in GB/T 3190. Check the current revision named on your order; minor limits for impurities can differ between editions.
Mechanical and physical properties
GB/T 3191 requires extruded 7A09 bar in T6 and T6511 to meet minimums of the order of 530 MPa tensile, 400 MPa yield and 6 % elongation for common sizes. Typical results are close to 7075-T6.
| Condition | Tensile strength | Yield strength | Elongation | Hardness |
|---|---|---|---|---|
| 7A09-T6 / T6511, GB minimum (common sizes) | ≥ 530 MPa | ≥ 400 MPa | ≥ 6 % | — |
| 7A09-T6, approximate typical | About 560 – 590 MPa | About 490 – 520 MPa | About 9 – 11 % | About 150 HB |
| 7A09-T73, approximate typical | About 490 – 510 MPa | About 420 – 440 MPa | About 12 % | About 135 HB |
| 7A09-O | About 250 MPa maximum | — | Over 10 % | About 60 HB |
Physical properties
- Density
- About 2.80 – 2.85 g/cm³ (7075 is 2.81 g/cm³)
- Modulus of elasticity
- About 71 GPa
- Electrical conductivity
- About 33 % IACS (T6); about 40 % IACS (T73)
- Thermal conductivity
- About 130 W/m·K (T6)
- Melting range
- About 475 – 635 °C
7A09 bar tempers
T651 / T6511
T6 with stretch stress relief (T651 for rolled or cut bar, T6511 for extruded bar with minor straightening). Preferred for heavy machining.
T73 / T7351
Over-aged for high stress-corrosion resistance. Choose for parts under sustained load, accepting about 10 – 15 % lower strength.
O
Annealed for forming or forging stock.
7A09 bar sizes and weights
Supply range
- Round bar
- About 6 – 300 mm diameter; larger as forged bar
- Square and rectangular bar
- Per drawing, extruded or cut from plate
- Length
- Common 1.5 – 6 m, or cut to length
- Surface
- As extruded, peeled or turned
| Diameter (mm) | kg per metre (2.81 g/cm³) | kg per 3 m bar |
|---|---|---|
| 6 | 0.08 | 0.2 |
| 10 | 0.22 | 0.7 |
| 16 | 0.56 | 1.7 |
| 20 | 0.88 | 2.6 |
| 25 | 1.38 | 4.1 |
| 32 | 2.26 | 6.8 |
| 40 | 3.53 | 10.6 |
| 50 | 5.52 | 16.6 |
| 63 | 8.76 | 26.3 |
| 80 | 14.12 | 42.4 |
| 100 | 22.07 | 66.2 |
| 125 | 34.48 | 103.5 |
| 160 | 56.50 | 169.5 |
| 200 | 88.28 | 264.8 |
| 250 | 137.94 | 413.8 |
| 300 | 198.63 | 595.9 |
Inspection and certification
Typical requirements
- Dimensions
- Diameter, straightness and length to GB/T or ASTM tolerance tables
- Mechanical
- Tensile test per lot; hardness and conductivity as process checks
- Ultrasonic
- On request for larger bars used in critical parts
- Certification
- EN 10204 3.1 certificate with chemistry, properties and lot traceability
Machining, joining and finishing
Machining
Excellent in T6 and T651: short chips, good finish. Use stretched tempers for deep pockets.
Joining
Not fusion-welded. Bolted or riveted.
Anodising
Takes sulphuric, chromic and hard anodising.
Stress corrosion
Use T73 for parts under sustained transverse load.
Applications of 7A09 bar
- Airframe: fittings, frames, beams and ribs machined from bar
- Landing gear and controls: brackets, links and actuator parts
- Seats and interiors: seat frames and brackets where weight matters
- Avionics: machined housings and mounting frames
- Industrial and defence: high-strength tooling, fixtures and components
How to order 7A09 bar
- SpecifyAlloy and temper, diameter or section, length, quantity and the governing specification with its revision letter (GB/T 3191 with GB/T 3190 chemistry, or AMS 4122 / AMS 4124 / ASTM B211 for 7075). Add any customer or prime-contractor material specification that sits on top of the AMS.
- ConfirmWe confirm the specification can be met, the tolerance class, any extra tests (ultrasonic class, conductivity, fracture toughness, grain flow) and the delivery terms (EXW, FOB, CIF or DAP).
- InspectMaterial is checked for dimensions, surface condition and marking; 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 giving chemistry, mechanical results and heat-treatment lot, traceable to the cast number.
- Pack and shipExport packing in sealed, moisture-protected wooden cases or on pallets, shipped by sea or air to your port or door.
References and standards
- GB/T 3190 – Wrought aluminium and aluminium alloys: chemical composition
- GB/T 3191 – Aluminium and aluminium alloy extruded bars
- SAE AMS 4122 – Bars, Rods and Wire, 7075-T6 / T651
- The Aluminum Association – International Alloy Designations and Chemical Composition Limits (Teal Sheets)
7A09 aerospace aluminium (aluminum) bar: FAQ
Is 7A09 the same as 7075?
The chemistry ranges overlap almost completely and the properties are nearly identical. A cast that meets both sets of limits can be dual-certified; otherwise substitution needs approval from the design authority.
What was 7A09 called before?
LC9, under the older Chinese designation system.
What is the minimum strength of 7A09-T6 bar?
GB/T 3191 requires about 530 MPa tensile, 400 MPa yield and 6 % elongation for common sizes of extruded T6 bar.
Can 7A09 bar be supplied to AMS 4124?
AMS 4124 is a 7075-T7351 specification. We can supply 7075 bar certified to it, or dual-certified material where the chemistry meets both grades.
Which temper should I order for heavy machining?
T651 or T6511. The stretch stress relief keeps the part from distorting as material is removed.
Do you supply 7A09 bar worldwide?
Yes, with EN 10204 3.1 certificates and export packing.
Need 7A09 bar?
Send diameter, temper, length and standard. We will confirm availability, certification and a delivered price.
