Aluminum 7039-O (Annealed)
Temper
AA 7039 · UNS A97039
Softest condition for severe forming or machining before solution treatment and ageing.
Values for the O condition
Other 7039 tempers and conditions
7039 is listed in 8 conditions; see the grade overview at 7039.
Compare all 8 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
OThis page Annealed | Softest condition for severe forming or machining before solution treatment and ageing. | 115 | 235 | 20 | 65 HB | 40 % IACS |
Solution heat treated and overaged (stabilized) | Overaged for maximum stress-corrosion and exfoliation resistance in thick sections or marine/humid service; ~10 % strength loss vs T6. | 330 | 400 | 13 | 118 HB | 40 % IACS |
T6 variant, underaged | Milder quench to limit distortion and residual stress in complex sections, at a small strength cost. | 345 | 415 | 13 | 122 HB | 36 % IACS |
Solution heat treated and underaged/two-step aged | Preferred armor temper: slightly lower strength than T6 but better toughness, spall resistance and stress-corrosion behaviour. | 345 | 415 | 13 | 122 HB | 37 % IACS |
Solution heat treated, stretched, aged | Thick-plate stress-relieved T6 variant used where symmetrical machining stability is critical. | 370 | 440 | 12 | 130 HB | 35 % IACS |
T6, stress relieved by stretching | T6 plate with controlled stretch for low residual stress — choose when heavy machining of thick plate is required. | 379 | 448 | 13 | 133 HB | 35 % IACS |
T6Default Solution heat treated and artificially aged | Highest strength condition; standard for welded high-strength structures where SCC exposure is controlled. | 380 | 450 | 13 | 133 HB | 35 % IACS |
Solution heat treated and specially aged | Armor-plate ageing practice balancing ballistic limit against back-face spall; specified in US armor plate specifications. | 385 | 450 | 12 | 132 HB | 36 % IACS |
What is 7039-O?
7039-O is 7039 in the O temper — softest condition for severe forming or machining before solution treatment and ageing. 7039-O has a yield strength of 115 MPa (16.7 ksi) and a tensile strength of 235 MPa (34.1 ksi) — weaker than 79% of aluminum grades. Elongation at break is 20% and the elastic modulus is 69.6 GPa (10.1 Msi). 7039-O has a density of 2.74 g/cm³ (0.099 lb/in³), heavier than 64% of aluminum grades. It melts at 585°C (1,085 °F). T6 is the default condition FabDigit quotes; O is available on request or by drawing note.
Advantages
- Ductile — tolerates forming and impact — 20%, better than 89% of aluminum grades
- Forms and bends easily — 80/100, better than 89% of aluminum grades
- Conducts heat well — 170 W/m·K (98.2 BTU/hr·ft·°F), better than 82% of aluminum grades
- Tough — resists crack growth — 30 MPa·√m (27.3 ksi·√in), better than 76% of aluminum grades
Limitations
- Low strength — 115 MPa (16.7 ksi), worse than 79% of aluminum grades
- Limited service temperature — 120°C (248 °F), worse than 79% of aluminum grades
7039-O properties
Typical room-temperature values for 7039-O; 10 are specific to this condition. Other listed values are 7039 reference data and may not represent this condition. Bars are the position among aluminum grades.
Physical3
7039-O has a density of 2.74 g/cm³ (0.099 lb/in³), heavier than 64% of aluminum grades. It melts at 585°C (1,085 °F).
Mechanical12
7039-O has a yield strength of 115 MPa (16.7 ksi) and a tensile strength of 235 MPa (34.1 ksi) — weaker than 79% of aluminum grades. Elongation at break is 20% and the elastic modulus is 69.6 GPa (10.1 Msi).
Thermal6
7039-O is rated for continuous service to 120°C (248 °F). It conducts heat at 170 W/m·K (98.2 BTU/hr·ft·°F), better than 82% of aluminum grades. Thermal expansion is 23.4 µm/m·K (13 µin/in·°F).
Electrical3
7039-O conducts electricity at 40 % IACS, better than 72% of aluminum grades.
Chemical & Environmental3
Corrosion resistance is good (55/100), worse than 51% of aluminum grades.
Sustainability4
Producing a kilogram of 7039-O takes about 205 MJ of energy and emits 12.5 kg of CO₂ — more than 76% of aluminum grades. Typical recycled content is 20%.
Manufacturability8
7039-O's machinability is fair (45/100, worse than 72% of aluminum grades); weldability very good (75/100); formability very good (80/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 7039-O
Is 7039 easy to machine?
Machines like other aged 7000-series plate — high cutting speeds, sharp polished-flute carbide tooling and flood coolant give good chips; stress-relieved (T651) stock avoids warpage in deep pocketing.
Can 7039 be welded?
Designed for GMAW/GTAW with 5183/5356 (or 5039) filler; HAZ recovers a useful fraction of strength by natural ageing, but avoid sustained tensile stress across weld HAZ in T6 due to SCC risk.
Can 7039 be formed, bent or molded?
Form in O or freshly solution-treated (W) condition; T6/T64 plate has limited cold bending and needs generous bend radii or warm forming.
What surface finishes work on 7039?
Takes clear, hard and chromate/anodic coatings well; for military use it is normally chemical-conversion coated and painted (CARC), and welds anodize a different shade than parent metal.
7039 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 |
|---|---|---|
| Siimpurity limit | ≤ 0.3 | 0.1 |
| Feimpurity limit | ≤ 0.4 | 0.2 |
| Cukept low for weldability | ≤ 0.1 | 0.03 |
| Mn | 0.1 – 0.4 | 0.25 |
| Mg | 2.3 – 3.3 | 2.8 |
| Crgrain-structure control | 0.15 – 0.25 | 0.2 |
| Zn | 3.5 – 4.5 | 4 |
| Tigrain refiner | ≤ 0.1 | 0.03 |
| Others (each) | ≤ 0.05 | |
| Others (total) | ≤ 0.15 | |
| Al | balance |
7039-O — frequently asked
What is 7039-O used for?
7039-O is typically used for military vehicle armor plate, armored hull and cab structures, turret and hatch weldments, ballistic protection panels, armored personnel carrier bodies and welded military bridging and shelters. In short: weldable 7000-series armor; marine and military.
What is the yield strength of 7039-O?
7039-O has a typical yield strength of 115 MPa (16.7 ksi) and a tensile strength of 235 MPa (34.1 ksi) — weaker than 79% of aluminum grades. Strength varies by condition: see the 8 listed tempers.
Is 7039-O easy to machine?
Reasonably — machinability is rated fair (45/100, worse than 72% of aluminum grades). Machines like other aged 7000-series plate — high cutting speeds, sharp polished-flute carbide tooling and flood coolant give good chips; stress-relieved (T651) stock avoids warpage in deep pocketing.
Can 7039-O be welded?
Yes — weldability is rated very good (75/100). Designed for GMAW/GTAW with 5183/5356 (or 5039) filler; HAZ recovers a useful fraction of strength by natural ageing, but avoid sustained tensile stress across weld HAZ in T6 due to SCC risk.
What surface finishes work on 7039-O?
Takes clear, hard and chromate/anodic coatings well; for military use it is normally chemical-conversion coated and painted (CARC), and welds anodize a different shade than parent metal.
Can 7039-O be formed, bent or molded?
Form in O or freshly solution-treated (W) condition; T6/T64 plate has limited cold bending and needs generous bend radii or warm forming.
What is the maximum service temperature of 7039-O?
7039-O 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 7039-T6 and 7039-O?
T6 is the default condition — highest strength condition; standard for welded high-strength structures where SCC exposure is controlled. O: softest condition for severe forming or machining before solution treatment and ageing. Yield strength is 380 MPa in T6 versus 115 MPa in O.
Can FabDigit make parts in 7039-O?
Yes — 7039-O is available for CNC machining and sheet metal; every part is priced by an engineer rather than instantly. Upload a STEP file to get a price and a DFM check.
Sources
- International Alloy Designations and Chemical Composition Limits for Wrought Aluminum (Teal Sheets) — The Aluminum Association (2018)
- MIL-DTL-46063H — Armor Plate, Aluminum Alloy 7039 — US DoD (1998)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys — ASM International (1990)
- ASM Handbook Vol. 19 — Fatigue and Fracture — ASM International (1996)
- ASM Handbook Vol. 13B — Corrosion: Materials — ASM International (2005)
- MMPDS-style typical mechanical data for 7000-series wrought products — Battelle/FAA (2023)
- SMM / Mysteel (2026)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.