Aluminum 7A09
GB 7A09
7A09 (LC9) is a peak-strength Al-Zn-Mg-Cu alloy in the GB/T 7000-series family, precipitation hardened to the property level of 7178.
Reference datasheet — 7A09 is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the T6 condition
7A09 tempers and conditions
7A09 is supplied in 10 conditions, soft to hard. T6 is the default FabDigit quotes; the values on this page are for it.
Compare all 10 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Annealed | Softest condition for deep forming, straightening or machining before heat treatment; must be re-solution treated and aged for service. | 105 | 230 | 16 | 60 HB | 47 % IACS |
T73, stress relieved by stretching | Thick plate for machined airframe fittings needing both low residual stress and SCC immunity. | 420 | 490 | 12 | 130 HB | 40 % IACS |
Solution heat treated and overaged for stress-corrosion resistance | Pick for short-transverse loaded forgings and fasteners in humid/marine service where SCC must be eliminated, accepting ~10% lower strength. | 435 | 505 | 11 | 135 HB | 40 % IACS |
T74, stress relieved by stretching | Thick plate version of T74 for machined spars/bulkheads balancing strength, toughness and SCC resistance. | 445 | 515 | 11 | 137 HB | 38 % IACS |
Overaged between T73 and T76 | Compromise temper for heavy forgings: most of the T73 SCC benefit with higher strength than T73. | 455 | 525 | 10 | 140 HB | 38 % IACS |
T76, stress relieved by stretching | Stress-relieved T76 for machined thin-web panels needing exfoliation resistance and dimensional stability. | 460 | 525 | 10 | 140 HB | 38 % IACS |
T6, heat treated by the user | Choose when parts are formed/forged soft and heat treated after machining; properties slightly below mill T6. | 470 | 545 | 7 | 145 HB | 33 % IACS |
Overaged for exfoliation-corrosion resistance | Sheet/extrusion temper for thin skins and stringers where exfoliation resistance is required but T73 strength loss is unacceptable. | 470 | 535 | 9 | 142 HB | 38 % IACS |
T6, stress relieved by stretching | Plate temper for thick machined structures where low residual stress and dimensional stability matter. | 495 | 560 | 9 | 148 HB | 33 % IACS |
T6Default Solution heat treated and artificially aged | Default stocked condition: maximum strength for bar, extrusion and forging where SCC exposure is controlled. | 505 | 570 | 8 | 150 HB | 33 % IACS |
What is 7A09?
7A09 (LC9) is a peak-strength Al-Zn-Mg-Cu alloy in the GB/T 7000-series family, precipitation hardened to the property level of 7178. Default aged values are 505 MPa yield, 570 MPa tensile, 8 % elongation and about 150 HB, with thermal conductivity of 130 W/m·K and 33 % IACS; it is stocked as plate, extrusions and forgings for high-load airframe parts. Ductility, formability and corrosion resistance (score 38) are low, service temperature is capped near 120 °C, and the alloy is not arc weldable. Use 7A04/7075 where slightly lower strength buys better toughness. 7A09 has a density of 2.8 g/cm³ (0.101 lb/in³), heavier than 81% of aluminum grades. It melts at 477°C (891 °F). 7A09 has a yield strength of 505 MPa (73.2 ksi) and a tensile strength of 570 MPa (82.7 ksi) — stronger than 96% of aluminum grades. Elongation at break is 8% and the elastic modulus is 71 GPa (10.3 Msi).
What is 7A09 used for?
- aircraft structural parts
- high-strength forgings
- machined structural components
Advantages
- High strength — 505 MPa (73.2 ksi), better than 96% of aluminum grades
- Easy to machine — 72/100, better than 80% of aluminum grades
Limitations
- Difficult to weld — 18/100, worse than 94% of aluminum grades
- Limited service temperature — 120°C (248 °F), worse than 79% of aluminum grades
- Needs corrosion protection — 38/100, worse than 79% of aluminum grades
7A09 properties
Typical room-temperature values for 7A09-T6; bars are the position among aluminum grades.
Physical3
7A09 has a density of 2.8 g/cm³ (0.101 lb/in³), heavier than 81% of aluminum grades. It melts at 477°C (891 °F).
Mechanical15
7A09 has a yield strength of 505 MPa (73.2 ksi) and a tensile strength of 570 MPa (82.7 ksi) — stronger than 96% of aluminum grades. Elongation at break is 8% and the elastic modulus is 71 GPa (10.3 Msi).
Thermal6
7A09 is rated for continuous service to 120°C (248 °F). It conducts heat at 130 W/m·K (75.1 BTU/hr·ft·°F), worse than 65% of aluminum grades. Thermal expansion is 23.4 µm/m·K (13 µin/in·°F).
Electrical3
7A09 conducts electricity at 33 % IACS, worse than 57% of aluminum grades.
Chemical & Environmental3
Corrosion resistance is fair (38/100), worse than 79% of aluminum grades.
Sustainability4
Producing a kilogram of 7A09 takes about 210 MJ of energy and emits 12.5 kg of CO₂ — more than 88% of aluminum grades. Typical recycled content is 15%.
Manufacturability8
7A09's machinability is very good (72/100, better than 80% of aluminum grades); weldability poor (18/100); formability poor (22/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the aluminum family
Yield strength against density for every aluminum grade FabDigit runs. 7A09 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 7A09
Is 7A09 easy to machine?
Excellent chip formation in T6/T73; use sharp carbide, high speed and flood coolant, and rough from stress-relieved (T651/T7351) stock to avoid distortion.
Can 7A09 be welded?
Not arc-weldable (hot cracking, severe HAZ SCC); join by fasteners, bonding or friction stir welding, and re-heat-treat if welded.
Can 7A09 be formed, bent or molded?
Form in O or freshly quenched W temper; hot forge/extrude at ~380–450 °C, then solution treat 465–475 °C, water quench and age (T6: ~120 °C; T73/T74: two-step overage).
7A09 chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| Zn | 5.1 – 6.1 | 5.6 |
| Mg | 2 – 3 | 2.5 |
| Cu | 1.2 – 2 | 1.6 |
| Crgrain-boundary control / SCC resistance | 0.16 – 0.3 | 0.22 |
| Mn | ≤ 0.15 | |
| Feimpurity | ≤ 0.5 | |
| Siimpurity | ≤ 0.5 | |
| Ti | ≤ 0.1 | |
| Other (each)total 0.15 max | ≤ 0.05 | |
| Al | balance |
What surface finishes work on 7A09?
Chromate/trivalent conversion coat or Type II/III anodize for corrosion protection; anodic film is grey-bronze, so decorative bright anodizing is not recommended.
Surface treatments FabDigit runs on aluminum parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Organic Coating
Equivalent designations
Standards and trade names that resolve to Aluminum 7A09 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- GB (China)
- LC9
How much does 7A09 cost?
7A09 is a premium-cost aluminum ($$$), cheaper than about 51% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
7A09 — frequently asked
What is 7A09 used for?
7A09 is typically used for aircraft structural parts, high-strength forgings and machined structural components. In short: highest-strength 7000-series grade; 7178-equivalent property level; low ductility, not weldable.
What is the yield strength of 7A09?
7A09 has a typical yield strength of 505 MPa (73.2 ksi) and a tensile strength of 570 MPa (82.7 ksi) — stronger than 96% of aluminum grades. Strength varies by condition: see the 10 listed tempers.
Is 7A09 easy to machine?
Yes — machinability is rated very good (72/100, better than 80% of aluminum grades). Excellent chip formation in T6/T73; use sharp carbide, high speed and flood coolant, and rough from stress-relieved (T651/T7351) stock to avoid distortion.
Can 7A09 be welded?
Not readily — weldability is rated poor (18/100). Not arc-weldable (hot cracking, severe HAZ SCC); join by fasteners, bonding or friction stir welding, and re-heat-treat if welded.
What surface finishes work on 7A09?
Chromate/trivalent conversion coat or Type II/III anodize for corrosion protection; anodic film is grey-bronze, so decorative bright anodizing is not recommended.
Can 7A09 be formed, bent or molded?
Form in O or freshly quenched W temper; hot forge/extrude at ~380–450 °C, then solution treat 465–475 °C, water quench and age (T6: ~120 °C; T73/T74: two-step overage).
What is the maximum service temperature of 7A09?
7A09 is rated for continuous use to about 120°C (248 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 7A09-T6 and 7A09-O?
T6 is the default condition — default stocked condition: maximum strength for bar, extrusion and forging where SCC exposure is controlled. O: softest condition for deep forming, straightening or machining before heat treatment; must be re-solution treated and aged for service. Yield strength is 505 MPa in T6 versus 105 MPa in O.
How much does 7A09 cost?
7A09 is a premium-cost aluminum ($$$), cheaper than about 51% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- ASM Handbook Vol. 2 — Properties of Nonferrous Alloys (7075/7178 data) — ASM International (1990)
- MMPDS-16 typical/design values for 7000-series wrought products — Battelle/FAA (2021)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.