6061 vs 7075 Aluminium: Choosing the Right Grade for Machined Parts

Aluminium 6061 and 7075 are the two grades that dominate custom machining, and drawings arrive specifying the wrong one surprisingly often. They are both aluminium, both widely stocked, both easy to anodise — and in practice they behave like different materials entirely. This comparison tells you which one belongs on your drawing, and why the answer is usually 6061.

The Short Version

7075 is stronger; 6061 is better at almost everything else. 7075-T6 delivers roughly double the tensile strength of 6061-T6, which is why it is the aerospace and performance-grade alloy. 6061 answers back with better corrosion resistance, easier welding, lower cost and wider availability — which is why it is the default choice for everything that is not flying.

Full Comparison

Property	6061-T6	7075-T6
Tensile strength	≈ 310 MPa	≈ 570 MPa
Yield strength	≈ 270 MPa	≈ 500 MPa
Machinability	Excellent — clean chips, fine finish	Good — slightly more abrasive, still fine
Corrosion resistance	Good in most environments	Poorer — susceptible to stress corrosion; often clad or coated
Weldability	Good (loses some strength in the zone)	Poor — generally not welded
Anodising	Even, predictable results	Works, but colour can vary more
Relative material cost	Baseline	Roughly 1.5–2× more expensive
Availability	Plate, bar, tube — everywhere	Plate and bar — good but less universal
Typical uses	Housings, brackets, fixtures, enclosures	Aircraft fittings, high-strength links, tooling plates

Where 7075 Earns Its Premium

• Weight-critical strength. When a bracket must carry the same load at half the cross-section, 7075 is the honest answer — the classic aerospace trade.
• Fatigue and impact loading. Parts that see cycling loads — links, actuators, performance equipment — benefit from its higher fatigue strength.
• Premium tooling plates. Its hardness and stability make it a favourite for fixtures and mould bases that must not dent or wear.
• High-pressure components. Where yield strength sets the pressure limit, 7075 raises the ceiling without growing the part.

Where 6061 Is the Smarter Specification

• Anything exposed to weather or salt. Its corrosion resistance beats 7075 clearly; on 7075 you would add cladding or coating to catch up.
• Welded assemblies. 7075 effectively cannot be welded; 6061 welds with predictable (if reduced) strength.
• Cosmetic anodised parts. More consistent colour, fewer surprises batch to batch.
• Budget-sensitive production. The material saving compounds at volume, and machining is slightly faster too.
• Most general engineering parts. If the strength calculation passes with margin on 6061, the extra capability of 7075 is money spent for nothing.

A Simple Decision Rule

1. Size the part on 6061-T6 first.
2. If it passes with comfortable margin — stop. 6061 is the answer.
3. If it fails on strength, or the size penalty of 6061 breaks the design, move to 7075.
4. If the part must be welded, 6061 by default.
5. If it lives outdoors or near salt, 6061 unless strength truly forbids it — then 7075 with a protective finish.

For tolerance capability on these alloys, our aluminium tolerances guide covers ISO 2768 limits and the cost of tightening them.

Notes on Machining Each Grade

Both machine beautifully by metal standards, with small differences worth knowing. 7075's higher hardness gives excellent edge finish and very fine turned surfaces but wears tooling slightly faster. 6061 cuts fast and clean, tends to build up edge on worn tools, and produces the best anodised cosmetic finish of the common alloys. Both hold routine tolerances of ±0.05 mm and precision work to ±0.01 mm without difficulty — material choice changes the strength of the part far more than its machinability.

Frequently Asked Questions

Is 7075 always worth the extra cost?

No. It is worth it when strength-to-weight or fatigue performance is the binding constraint. For the majority of machined parts, 6061 passes the calculation and costs less.

Can 7075 be anodised black?

Yes, though results are less uniform than on 6061 because of the alloy's copper and zinc content. For colour-critical parts we recommend 6061 or a sample approval first.

Which grade machines faster?

6061 generally allows higher material removal rates. The difference is real but modest — the larger cost difference is in the raw material itself.

Do you stock both grades?

Yes — both are standard stock items in plate and bar, and we supply material certificates on request. See the full range on our metal materials page.

Related Reading

• CNC Machining Metal Materials
• CNC Machining Aluminium Tolerances: A Practical Guide
• Anodizing vs Powder Coating: Which Finish to Choose?
• CNC Machining for the Aerospace Industry

Not sure which grade your part needs? Send the drawing and the loads — we will check the calculation and tell you if a cheaper alloy will do the job.