Material Insight
Aluminum 6061 vs 7075 for CNC Machining: A Mechanical Engineer's Selection Guide
By YKWiki Engineering Team · Published 2026-05-30
The Aluminum Dichotomy
Aluminum 6061-T6 and 7075-T6 together account for the vast majority of CNC machined aluminum components. 6061 offers excellent machinability, weldability, corrosion resistance, and a moderate strength level. 7075 offers strength approaching that of mild steel — but at the cost of significantly worse corrosion resistance and an inability to be fusion welded. Selecting between them is about matching the alloy to the application's primary constraint.
Properties at a Glance
| Property | 6061-T6 | 7075-T6 |
|---|---|---|
| Tensile Strength | 310 MPa | 572 MPa |
| Yield Strength | 276 MPa | 503 MPa |
| Elongation | 12% | 11% |
| Density | 2.70 g/cm³ | 2.81 g/cm³ |
| Machinability | Good (50%) | Fair (70% rating) |
| Weldable | ✅ Yes (TIG/MIG) | ❌ Not recommended |
Selection Guidelines
Choose 6061-T6 when: Welding is required, corrosion resistance is a priority, cost is the primary constraint, or the application operates below 150°C with moderate loads. Choose 7075-T6 when: Strength-to-weight ratio is the design driver (aerospace, high-performance bicycle/motorcycle components), the part will be anodized (7075 anodizes to a harder surface), or operating stress exceeds 6061-T6's fatigue limit. The 50% raw material cost premium for 7075 is typically dwarfed by machining time savings in complex parts — 7075's superior chip breaking characteristics often reduce cycle time by 15-25%.
References & Standards
- ASTM International. Steel & Alloy Standards. astm.org
- International Organization for Standardization (ISO). iso.org
- National Institute of Standards and Technology (NIST). Materials Data. nist.gov
- ASM International. Materials Information Society. asminternational.org
- World Steel Association. Steel Statistical Yearbook. worldsteel.org