7000 Series Aluminum
The 7000 series is alloyed with zinc (5–8 %) plus magnesium and copper and heat-treated to the highest strengths of any aluminum — 7075-T6 yields around 500 MPa, on par with many structural steels at a third of the weight. The price is lower corrosion resistance and stress-corrosion sensitivity in the peak (T6) temper, which the over-aged T73 and T76 tempers trade some strength to fix, and it is not fusion-welded for structural use.
Popular 7000 series grades
Compare in the explorer| Grade | Yield, MPa | Tensile, MPa | Density, g/cm³ | Machinability | Weldability | Best for |
|---|---|---|---|---|---|---|
| 7075 | 503 | 572 | 2.81 | Very good | Poor | Highest-strength machined parts and fittings (T73 where stress corrosion is a risk) |
| 7050 | 469 | 524 | 2.83 | Very good | Poor | Thick aerospace plate, through-thickness properties |
| 7175 | 455 | 524 | 2.8 | Very good | Not recommended | High-toughness forgings |
| 7475 | 421 | 490 | 2.81 | Very good | Poor | Fracture-critical sheet and plate |
| 7068 | 683 | 710 | 2.85 | Very good | Not recommended | The strongest commercial aluminum |
| 7020 | 340 | 385 | 2.78 | Good | Very good | The weldable 7000 series; bicycle frames |
| 7055 | 634 | 655 | 2.85 | Good | Poor | Highest strength 7000 series |
Choose the 7000 series for
Parts where aluminum must carry the highest possible load: aircraft fittings and ribs, racing and bicycle components, mold and tooling plates, high-pressure manifolds, prototype parts standing in for steel at a third of the weight.
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7000 series by application
- Aircraft fittings and structure
- 7075-T6 and T651 for machined fittings, 7050-T7451 for plate over 75 mm where 7075 loses properties through the thickness, 7475 where fracture toughness is specified.
- Racing, bicycle and outdoor gear
- 7075-T6 for cranks, uprights, hubs and links; 7005 and 7020 for welded frames — the one branch of the family that can be welded and naturally re-ages.
- Molds and tooling
- 7075-T651 and the proprietary mold plates built on it (QC-10, Hokotol, Alumold) for prototype injection molds and blow molds that must run thousands of shots.
- When 7075 is not enough
- 7068-T6511 reaches about 630 MPa yield — the strongest aluminum sold — for ordnance, high-end sporting goods and space parts; 7150 and 7055 are the aerospace equivalents.
Working with the 7000 series
- Machining
- Excellent — hard, free-cutting, fine finish, holds tolerance like a steel. Thick 7075-T6 plate carries residual stress and distorts after pocketing; buy T651 or T7351 and rough from both sides.
- Welding
- 7075, 7050 and 7175 are not fusion-welded for structural use: hot cracking and a very soft weld zone. 7005 and 7020 weld with 5356 filler and recover much of their strength by natural ageing. Design the rest as one machined piece or fasten.
- Corrosion and stress corrosion
- T6 is susceptible to stress-corrosion cracking under sustained tension in the short-transverse direction; T73 / T7351 trade about 10 % strength to remove the problem. Chem-film or anodize plus primer for anything outdoors or marine.
Other aluminum series
7000 Series Aluminum — frequently asked
What is 7000 series aluminum?
The 7000 series is alloyed with zinc (5–8 %) plus magnesium and copper and heat-treated to the highest strengths of any aluminum — 7075-T6 yields around 500 MPa, on par with many structural steels at a third of the weight. The price is lower corrosion resistance and stress-corrosion sensitivity in the peak (T6) temper, which the over-aged T73 and T76 tempers trade some strength to fix, and it is not fusion-welded for structural use.
Which grade of 7000 series aluminum should I use?
7075-T6 for the highest-strength machined parts: aircraft fittings, racing components, molds and high-stress brackets; 7075-T73 or T7351 where stress corrosion is a risk (thick sections, marine exposure). 7050-T7451 for thick aerospace plate — it keeps its properties through the thickness, which 7075 does not above about 75 mm. 7175 and 7475 are the higher-toughness forging and sheet versions; 7068 is the strongest commercial aluminum, used where 7075 is not quite enough. For an everyday machined part 6061-T6 costs a third as much and welds; choose 7075 only when the design uses the strength.
Which grade of 7000 series aluminum is the strongest?
7068 has the highest yield strength in the series at 683 MPa; 7095 follows at 675 MPa. Values are for each grade's default condition.
Which grade of 7000 series aluminum is easiest to machine?
7075 (machinability very good, 78/100), then 7175 (78/100).
Is 7000 series aluminum heat-treatable?
Yes. These grades gain their strength from heat treatment; the conditions and their properties are listed on each grade page.
7075 or 6061?
6061-T6 unless the calculation says otherwise: it costs about a third as much, machines slightly faster, welds and anodizes cleanly. Choose 7075-T6 when the part needs its roughly 80 % higher yield strength (≈ 500 vs 275 MPa) and will not be welded — fittings, high-load brackets, molds. Both machine to the same tolerances.
What is the difference between 7075-T6 and 7075-T73?
T6 is peak-aged: highest strength, but susceptible to stress-corrosion cracking under sustained load in the thickness direction. T73 is over-aged: about 10–15 % lower strength, immune to stress corrosion and better in exfoliation. Aerospace and marine parts under sustained load specify T73 / T7351; everything else runs T6.