6061 vs 7075 Aluminum
6061-T6 is the weldable, corrosion-resistant, easily anodized workhorse; 7075-T6 is roughly 85% stronger in tension but is not practically weldable and corrodes more readily.
- Rev
- 2026-08-11
Use 6061-T6 unless you have a specific reason not to — it welds, it anodizes cleanly, it resists corrosion, it comes in every mill form, and it costs less. Move to 7075-T6 when a strength-limited part has to get lighter or smaller: its 572 MPa (83 ksi) tensile and 503 MPa (73 ksi) yield are roughly 85% above 6061-T6's. If the part is stiffness-limited or must be welded, 7075 buys you nothing.
Both are heat-treatable wrought aluminum alloys, but from different families. 6061 is Al-Mg-Si (6xxx), strengthened by magnesium silicide. 7075 is Al-Zn-Mg-Cu (7xxx), the aerospace family, strengthened by zinc-magnesium precipitates with copper added.
Head-to-head
| Property | 6061-T6 | 7075-T6 |
|---|---|---|
| Alloy system | Al-Mg-Si (6xxx) | Al-Zn-Mg-Cu (7xxx) |
| Density | 2.70 g/cm³ (0.0975 lb/in³) | 2.81 g/cm³ (0.1015 lb/in³) |
| Ultimate tensile strength | 310 MPa (45 ksi) | 572 MPa (83 ksi) |
| Yield strength | 270 MPa (39.2 ksi) | 503 MPa (73 ksi) |
| Hardness | 95 HB | 150 HB |
| Young's modulus | 69 GPa (10.0 Msi) | 71.7 GPa (10.4 Msi) |
| Melting range | Solidus 580 °C, liquidus 650 °C (1,076–1,202 °F) | Solidus 480 °C, liquidus 640 °C (896–1,184 °F) |
| Weldability | Readily fusion welded with 4043 or 5356 filler; the heat-affected zone loses temper unless the part is re-solution treated and aged | Effectively non-weldable by fusion — the weld metal hot cracks. Join mechanically, adhesively, or by friction stir welding |
| Corrosion resistance | Good general atmospheric resistance | Lower. T6 is susceptible to stress corrosion cracking; the overaged T73 and T7351 tempers trade strength for SCC resistance, and aerospace sheet is often supplied Alclad |
| Anodizing response | Anodizes cleanly and consistently — clear or dyed Type II, predictable Type III hardcoat | Anodizes, but the zinc and copper give a darker and sometimes hazier film; hardcoat comes out noticeably darker |
| Machinability | Machines well but runs gummy; needs sharp tooling and good chip evacuation | Chips more cleanly and is generally the easier of the two to machine |
| Formability | Bends in T6 at moderate radii | Essentially unformable in T6; sheet is formed in O or W temper and heat treated afterward |
| Availability | Every mill form — extrusion, structural shape, bar, plate, sheet, tube. The commodity structural aluminum | Mainly plate, bar, and sheet; far fewer stock extruded shapes |
| Relative cost | Baseline | Commonly quoted at roughly twice 6061 per pound, and higher for aerospace-certified plate. Ratio varies with form and market |
Property values above come from the material properties chart; melting ranges from the metal melting points chart.
When to choose 6061-T6
Choose it whenever the joint is welded. Fabricated frames, tube structures, pressure housings, marine hardware, and heat exchangers rely on arc welding, and 6061 takes it. Design for the heat-affected zone: as-welded strength near the bead drops well below T6 unless the assembly is re-solution treated and artificially aged, so size the joint for the weakened condition or move the weld out of the high-stress region.
Choose it whenever the part is stiffness-driven. The two alloys differ by roughly 4% in Young's modulus — 69 GPa against 71.7 GPa — so a deflection-limited bracket, plate, or beam deflects essentially the same in either alloy. Paying twice the price for 7075 in a stiffness-limited part buys nothing at all. This is the single most common material selection error in aluminum design.
Choose it for anything extruded. 6061 is the extrusion workhorse and is stocked as angle, channel, tube, and thousands of custom extrusion profiles. Choose it for anything formed on a press brake — see the bend radius and K-factor chart — and for anything anodized to a consistent cosmetic finish, since 6061 gives anodizing a clean, repeatable color.
When to choose 7075-T6
Choose it when the part is strength-limited and weight or envelope is fixed. Aircraft fittings, wing spars, landing gear components, rifle receivers, high-load structural brackets, competition bicycle and motorsport parts, and mold plates for tooling all use 7075 because roughly 85% more tensile and yield strength at only 4% more density means a smaller, lighter part that carries the same load.
Choose it for hardness and wear on unlubricated surfaces. At 150 HB against 95 HB, 7075 galls and dents less — useful for fixture plates, jaws, and tooling that gets handled hard.
Then design around what it costs you. There is no fusion welding, so the assembly runs on mechanical fastening, adhesive bonding, or friction welding. There is no forming in T6, so sheet parts are formed soft and heat treated after. Corrosion protection is not optional in a marine or humid environment, and stress corrosion cracking in the short-transverse direction is a real failure mode in T6 — if sustained tensile stress and moisture are both present, specify a T73-type overaged temper and accept the strength penalty.
Cost comparison
| Situation | Pick | Why |
|---|---|---|
| Welded frame or weldment | 6061-T6 | 7075 cannot be fusion welded at all |
| Deflection-limited plate or bracket | 6061-T6 | Modulus differs by about 4%; the extra strength is unused |
| Strength-limited part, weight critical | 7075-T6 | About 85% more yield strength at 4% more density |
| Extruded profile or bent sheet | 6061-T6 | Stock shapes and formability in temper |
| Cosmetic anodized finish | 6061-T6 | Cleaner, more repeatable anodic film |
| Marine or high-humidity service | 6061-T6, or 7075 in a T73 temper | 7075-T6 is vulnerable to stress corrosion cracking |
| Fixture plates, tooling, hard-use surfaces | 7075-T6 | 150 HB against 95 HB |
Stock price is only part of the delta. 7075 is stocked in fewer forms, so a part that would have been an off-the-shelf 6061 extrusion may have to be machined from plate — which adds material removal, cycle time, and scrap on top of the higher per-pound cost. Where the strength really is needed and volume supports it, a near-net 7075 forging cuts the buy-to-fly ratio dramatically compared with hogging the shape out of plate.
Verdict
Default to 6061-T6 and justify any move away from it. Switch to 7075-T6 only when the part is strength-limited and the envelope or weight budget is fixed — its 503 MPa (73 ksi) yield against 6061-T6's 270 MPa (39.2 ksi) is about 85% more load capacity for 4% more density. Two conditions rule 7075 out outright: any fusion-welded joint, because 7075 hot cracks, and any stiffness-limited part, because the two alloys are within about 4% on Young's modulus (69 vs 71.7 GPa) and the extra strength goes unused. If you do specify 7075 in a humid or marine environment under sustained tensile stress, move to a T73-type overaged temper and accept the strength penalty rather than risk stress corrosion cracking.
Questions
6 questionsHow much stronger is 7075 than 6061?
About 85% stronger in both measures. 7075-T6 runs 572 MPa (83 ksi) ultimate tensile and 503 MPa (73 ksi) yield, against 310 MPa (45 ksi) and 270 MPa (39.2 ksi) for 6061-T6. Density rises only from 2.70 to 2.81 g/cm³ (0.0975 to 0.1015 lb/in³), so the strength-to-weight gain is nearly the full strength gain.
Can you weld 7075 aluminum?
Not by fusion welding, in practice. 7075 hot cracks in the weld metal and heat-affected zone, so it is not treated as a weldable alloy. Assemblies in 7075 are joined with mechanical fasteners, structural adhesive, or friction stir welding, which stays below the melting point. If the design requires a welded joint, use 6061 instead.
Is 7075 stiffer than 6061?
Barely, and not usefully. Young's modulus is 69 GPa (10.0 Msi) for 6061-T6 and 71.7 GPa (10.4 Msi) for 7075-T6 — about 4% apart. A deflection-limited part made from 7075 will deflect essentially the same as one made from 6061 with the same geometry, so the alloy upgrade buys nothing on a stiffness-driven design.
Which anodizes better, 6061 or 7075?
- It takes a clean, consistent Type II anodic film that dyes predictably and hardcoats to a repeatable appearance. The zinc and copper in 7075 produce a darker and sometimes hazier finish, and Type III hardcoat on 7075 comes out noticeably darker. If color consistency across a batch matters cosmetically, specify 6061.
Does 7075 corrode more than 6061?
Yes. 6061 has good general atmospheric corrosion resistance, while 7075 is less resistant and, in the T6 temper, is susceptible to stress corrosion cracking under sustained tensile stress in the short-transverse direction. The usual answers are an overaged T73 or T7351 temper, which trades strength for SCC resistance, Alclad sheet, or a protective anodic coating.
Can you bend 7075 sheet?
Not in the T6 temper — it cracks at radii 6061-T6 tolerates. Sheet parts in 7075 are formed in the annealed (O) or freshly quenched (W) temper and then heat treated to T6 afterward, which adds process steps and dimensional risk. For a bent part with no exceptional strength requirement, 6061-T6 is the straightforward choice.