Aluminum plate 6061-T6 and 7075-T6 are the two dominant high-strength aluminum plate choices for structural and machined parts. This guide compares the two alloys on strength, machinability, anodizing and cost, with selection guidance for tooling, aerospace, automotive and structural applications.
6061-T6 and 7075-T6 are the two alloys that engineers reach for when a part needs high strength, good machinability and reasonable cost. Both are heat-treated aluminum alloys, both are widely stocked, but they have very different microstructures: 6061 is an Al-Mg-Si alloy with moderate strength and excellent corrosion resistance; 7075 is an Al-Zn-Mg-Cu alloy with the highest strength of any common aluminum alloy but lower corrosion resistance. The choice between them depends on whether the part needs strength or durability.
Strength and Weight Comparison
6061-T6 aluminum plate has minimum yield strength of 35,000 psi (240 MPa) and ultimate tensile of 42,000 psi (290 MPa). 7075-T6 aluminum plate has minimum yield of 73,000 psi (500 MPa) and ultimate tensile of 83,000 psi (570 MPa), roughly twice the strength of 6061-T6. The density of both is essentially the same (about 2.81 g/cm³), so 7075 gives nearly twice the strength-to-weight ratio. For weight-critical applications where the part is heavily loaded, 7075 is the right call.
When 6061-T6 Is the Right Specification
6061-T6 aluminum plate is the right specification for most general structural and fabrication applications: machine frames, tooling plates, fixtures, jigs, brackets, automotive chassis components, bicycle frames, and structural members where the loading is moderate. It has excellent corrosion resistance (good for outdoor and marine exposure), is weldable by TIG and MIG with 4043 or 5356 filler, and anodizes beautifully for a decorative finish. It is also significantly cheaper than 7075 and easier to source in large plates up to 6 inches thick.
When 7075-T6 Is the Necessary Upgrade
7075-T6 aluminum plate is the right specification for highly loaded structural parts where weight matters: aerospace components, military applications, high-end bicycle and motorcycle parts, performance automotive suspension and chassis, and precision machined parts where stiffness is critical. 7075 is more difficult to weld (it is generally considered non-weldable for structural applications because of hot cracking), so it is usually machined from plate rather than fabricated. It also has lower corrosion resistance than 6061, so protective anodizing or painting is required for outdoor service.
Machining, Anodizing and Surface Finish
Both 6061-T6 and 7075-T6 machine well with sharp carbide tooling, though 7075 is slightly more aggressive on tools because of its higher hardness. For anodizing, 6061 gives a brighter, clearer finish that is preferred for decorative applications; 7075 anodizes to a slightly yellower tone due to its zinc content. For Type II (decorative) and Type III (hard) anodizing, 6061 is the better choice. For chrome-like or bright finishing, both are good substrates after polishing.
What to Specify on the Aluminum Plate RFQ
State the alloy and temper (6061-T6 or 7075-T6), the plate thickness, the width and length, the flatness and thickness tolerance (per ASTM B209 or AMS-QQ-A-250), and any special testing (ultrasonic for aerospace, mechanical properties per batch). For structural and fabrication, default to 6061-T6; for high-strength weight-critical parts, step up to 7075-T6. Confirm the mill supplies the test report per EN 10204 3.1 showing actual yield and tensile strength, since aluminum plate is often supplied with a wider strength range than the minimum.
Related Resources from Baobin Steel
- Aluminum sheet and plate catalog – 6061, 7075 and other alloys
- Aluminum products overview – grades and tempers
- Request a quote – send your drawing for aluminum plate pricing