Why Aluminum?
Aluminum is one-third the weight of steel with excellent corrosion resistance, good machinability, and a huge range of alloys for different applications. It’s the most commonly machined non-ferrous metal in job shops.
The Alloy Series
Aluminum alloys are grouped by their primary alloying element:
| Series | Alloying Element | Key Property |
|---|---|---|
| 1xxx | Pure aluminum (99%+) | Electrical conductivity, formability |
| 2xxx | Copper | High strength (aerospace) |
| 3xxx | Manganese | Moderate strength, formability |
| 5xxx | Magnesium | Weldability, marine corrosion |
| 6xxx | Magnesium + Silicon | Versatile — extrudable, weldable, machinable |
| 7xxx | Zinc | Highest strength aluminum alloys |
The Big Three for Manufacturing
6061-T6
The “default” aluminum for machining and fabrication. Good strength (45 ksi yield), good machinability, good weldability, good corrosion resistance. Available in every form: plate, bar, tube, extrusion.
- Use for: Brackets, frames, housings, fixtures, jigs, structural components
- Note: T6 temper means heat-treated and artificially aged. Welding kills the T6 temper in the heat-affected zone (drops to ~50% strength locally). Solution: weld in T4 and re-age, or design around the HAZ.
7075-T6
The strongest common aluminum alloy (73 ksi yield). Used where strength-to-weight ratio is critical.
- Use for: Aerospace, military, high-stress structural, rock climbing gear, bicycle components
- Note: Not weldable (cracks). Not as corrosion resistant as 6061. More expensive. Machine it, bolt it, don’t weld it.
5052-H32
The best aluminum for sheet metal forming. Excellent bendability and weldability. Moderate strength (28 ksi yield).
- Use for: Enclosures, panels, marine applications, fuel tanks, HVAC
- Note: Not heat-treatable — strengthened by cold working (H tempers). The go-to for bent aluminum parts.
Other Alloys Worth Knowing
| Alloy | Yield (ksi) | Best For |
|---|---|---|
| 2024-T3 | 50 | Aircraft skins and structures (legacy) |
| 6063-T6 | 31 | Extrusions — architectural, tubing, rails |
| 5083-H116 | 33 | Marine — boat hulls, offshore structures |
| MIC-6 | 24 | Cast aluminum plate — jig plate, ultra-flat, stress-free |
Temper Designations
- O: Annealed (soft, maximum formability)
- T4: Solution heat-treated, naturally aged (intermediate strength)
- T6: Solution heat-treated, artificially aged (full strength)
- T651: T6 + stress relieved by stretching (less distortion in machining)
- H32: Strain-hardened and stabilized (sheet metal forming)
Need help choosing the right alloy? Describe your project and we’ll recommend the best material.