Aluminum Grade Selection Chart for CNC Machining
A working shop's reference for picking the right aluminum — 6061, 7075, 5052, 2024, 6063, 2A12 — with real numbers, anodizing response, weldability, and a decision tree. Bookmark this page; we update it when suppliers ship new stock.
Why This Chart Exists
Every week a buyer emails us a drawing and asks "should this be 6061 or 7075?" Sometimes the answer is obvious. More often it isn't — and picking the wrong grade wastes a week of machining time, or worse, ships a part that fails in service.
We've machined over 200,000 aluminum parts since 2005. This chart is the shortlist of grades that actually come across our desks, with the numbers we wish someone had handed us on day one. The mechanical properties are typical values from ASM metals handbooks and our own CMM test reports. The "shop floor" notes are what we tell our own operators when a job comes in.
If you're not sure which column to use: jump to the decision tree at the bottom. If you're spec'ing a part that has to survive a stress simulation, also read the strength vs machinability section — that tradeoff decides 80% of parts.
All Six Grades at a Glance
Scroll right on mobile. Properties shown for the most common temper — T6 for heat-treated grades, H32/H34 for work-hardened. For other tempers see the footnotes.
| Property | 6061-T6 | 7075-T6 | 5052-H32 | 2024-T3 | 6063-T5 | 2A12-T4 |
|---|---|---|---|---|---|---|
| Yield strength (MPa) | 275 | 503 | 193 | 345 | 145 | 325 |
| Tensile strength (MPa) | 310 | 572 | 228 | 483 | 185 | 470 |
| Fatigue strength (MPa, 10⁷ cycles) | 96 | 159 | 117 | 138 | 69 | 138 |
| Elongation at break (%) | 12 | 11 | 12 | 18 | 12 | 19 |
| Density (g/cm³) | 2.70 | 2.81 | 2.68 | 2.78 | 2.70 | 2.78 |
| Melting range (°C) | 582–652 | 477–635 | 607–650 | 502–638 | 615–655 | 502–638 |
| Machinability rating (vs 2011=100%) | 90% | 80% | 50% | 70% | 60% | 75% |
| Weldability (TIG/MIG) | Excellent | Not recommended | Excellent | Poor | Excellent | Poor |
| Anodizing response | Excellent (color & hardcoat) | Acceptable (streaks possible) | Good (hardcoat only) | Limited (special process) | Excellent (decorative) | Limited |
| Corrosion resistance (atmospheric) | Good | Fair (prone to SCC) | Excellent (marine grade) | Poor | Good | Poor |
| Formability (cold) | Good | Poor | Excellent | Fair | Excellent | Fair |
| Relative cost (per kg, China mill, 2026) | 1.0× baseline | 1.4× | 1.05× | 1.3× | 1.0× | 1.1× |
| Typical applications | Frames, brackets, housings, general | Aerospace structural, high-stress parts | Sheet metal, marine, fuel tanks | Aircraft skins, truck wheels, screws | Extrusions, heat sinks, architectural | Aerospace skins, military (CN-spec) |
SCC = stress corrosion cracking. Costs are indicative; confirm with current mill quote. SCC resistance of 7075-T6 is markedly improved in the T73 temper (overaged, ~10% lower strength).
The Decision Tree
The one question that decides most parts
Ask: does this part see a peak stress above 200 MPa in service?
- No (most brackets, covers, housings, jigs, fixtures) — use 6061-T6. It's 40% cheaper than 7075, welds, anodizes beautifully, and is in stock at every mill in the world.
- Yes — read on.
The short answer for high-stress parts
If the part is loaded, your real choice is 7075-T6 or 2024-T3. Both are aerospace legacy grades with 50+ years of data. 7075 has higher static strength; 2024 has better fatigue life and fracture toughness. Most of our aerospace and robotics customers end up at 7075-T6 for machined fittings and 2024-T3 for sheet-metal-skinned components.
If the part also needs to be welded, your choice is no longer 7075 or 2024 — both are unweldable. Switch to 7005, or redesign with bolted joints, or change the base material to welded steel.
Full Decision Tree
- Need to weld? → Yes: 6061-T6, 5052-H32, or 6063-T5. No: continue.
- Peak stress > 350 MPa? → Yes: 7075-T6 (or 7075-T73 if corrosion is a concern). No: continue.
- Will it see saltwater or marine atmosphere? → Yes: 5052-H32 (sheet) or 6061-T6 (machined). No: continue.
- Need bright decorative anodizing (color match, gloss)? → Yes: 6061-T6 or 6063-T5. No: continue.
- Profile or extrusion cross-section? → Yes: 6063-T5 (extrudes cleaner) or 6061-T6 (stock shapes). No: continue.
- Need best chip-breaking for high-speed CNC? → Yes: 2024-T3 or 6061-T6. No: continue.
- Default: 6061-T6. It is the right answer most of the time.
What We Tell Our Own Operators
6061-T6 — the workhorse
Machines beautifully. Use sharp carbide, run 300 m/min on aluminum, flood coolant. Chip color should be light gold/blue — if you see long stringy chips sticking to the tool, the feed rate is too low or the tool is dull. Tolerances of ±0.01mm are achievable on features under 50mm.
7075-T6 — strong but moody
Harder on tools than 6061 (roughly 1.5x tool wear at the same parameters). Use lower cutting speeds (200 m/min) and higher feeds. Do not let chips weld to the insert — that's the #1 cause of 7075 parts failing surface finish inspection. After anodizing, 7075 can show streaky coloration; this is normal alloying-element segregation, not a defect.
5052-H32 — for sheet metal only
We rarely machine 5052 — it's soft, gummy, and chips ball up. It's a sheet metal grade. If you have a 5052 drawing with machined features, talk to us first; we'll often suggest 6061 instead for the machined version and weld or rivet a 5052 sheet on top.
2024-T3 — aerospace classic
Excellent machinability — short chips, good surface finish. But its corrosion resistance is poor; almost every 2024 part we ship gets alodine or anodized for protection. Do not use in marine environments bare.
6063-T5 — extrusions and heat sinks
Soft, with a smoother anodized finish than 6061. The "window frame" alloy. We see it mostly in architectural parts, LED heat sinks, and finned enclosures. Not a structural grade.
2A12-T4 — Chinese aerospace equivalent of 2024
Composition and properties are very close to 2024-T3 (within ~5%). The CN-spec name; if your drawing calls for 2A12, you can usually substitute 2024-T3 with no functional change. We stock both. Pricing is similar.
Aluminum Grade Questions We Get Every Week
What is the difference between 6061 and 7075 aluminum?
Which aluminum is best for anodizing?
Can 7075 aluminum be welded?
Which aluminum has the best machinability?
What is the cheapest aluminum for CNC machining?
Can I substitute 6061 for 7075 to save cost?
Send Us the Drawing — We'll Tell You Which Grade
If your part has a service load, a tolerance stack-up, a regulatory requirement (FDA, aerospace, marine), or just a tight budget, the answer is rarely obvious from a spec sheet. We've been machining these six grades daily since 2005 — send the drawing and we'll recommend the cheapest grade that meets your requirements, with a quote.