Both are Mg-Si 6xxx wrought alloys. 6061-T6/T651 is stronger and machines well for frames, brackets, fixtures. 6063-T5/T6 extrudes cleaner with superior surface finish for architectural trim, railings, window/door frames. Neither is a die-casting alloy; high-volume 3D shapes usually switch to A380/ADC12/AlSi10Mg die casting.
What are 6061 and 6063 aluminum?
6061 and 6063 are heat-treatable wrought aluminums. Most buyers see them as:
- 6061: plates, bars, and structural extrusions; great after T6/T651 heat treatment.
- 6063: primarily extrusions with tight corners and smooth skins; common in T5/T6.
Both weld, anodize, and machine—just with different strengths (literally and figuratively).
Which is stronger—6061 or 6063 strength comparison?
Short answer: 6061-T6/T651 > 6063-T6 > 6063-T5 for yield/UTS and fatigue. Choose 6061 when a profile must carry load, resist denting, or stay stiff over span. 6063 works when geometry (thicker wall, ribs) provides the stiffness and the priority is finish or forming.
Rule of thumb
- Long spans, fixtures, frames → 6061
- Decorative shapes, retail fixtures, window/door profiles → 6063
Which bends and forms better—6061 vs 6063
- 6063 usually bends easier (higher elongation), so it’s friendlier for tight radii and complex extrusions.
- 6061 can crack if you push radius limits in T6; consider T4/T42 for forming then re-age to T6.
Design cues
- Keep grain direction in mind for plate bends.
- Use larger inside radii for 6061-T6, especially on thin wall tubing.
Which welds and machines better 6061 vs 6063
Welding
- Both weld by GTAW/GMAW.
- Common filler choices: 4043 (good crack resistance, anodize color shift) or 5356 (higher strength, better color match).
- When welding to cast 3xx (A380/ADC12), 4043 is often preferred.
Machining
- 6061-T6/T651 is stiffer and generally machines better (fixtures, brackets, precision holes).
- 6063 machines fine for light duty but shines when the profile shape does most of the work.
How do finishes compare
- 6063 delivers the best cosmetic anodize (bright, uniform).
- 6061 anodizes well for functional protection but may show more grain/texture; great for hardcoat on wear areas.
- Powder coating and conversion coatings work on both; specify surface prep clearly.
What are the common tempers—T5, T6, T651 heat-treat routes
- 6063-T5: cooled from extrusion + artificially aged (fast, economical).
- 6063-T6: higher strength after full solution heat treat + age.
- 6061-T6: solution heat treat + artificial age (workhorse).
- 6061-T651: T6 plus stress-relief stretch—better stability for machining.
Where is each used in practice—applications & uses
6061 use cases
- Machine frames, jigs, fixtures
- Vehicle racks, structural brackets
- CNC parts from plate/bar when tight tolerances matter
6063 use cases
- Architectural trim, railings, window/door frames
- Display systems, clean decorative extrusions
- Heat-sink profiles where surface and thin walls matter
Is there a price or weight difference
- Density is essentially the same; weight differences come from geometry.
- 6063 often costs less per part for complex extrusions (easier to push, higher die yield).
- 6061 plate/bar pricing is competitive for machined components but extruded 6061 shapes may carry a slight premium vs 6063.
6061/6063 vs die casting
Neither 6061 nor 6063 is a die-casting alloy. For thin-wall, boss-rich 3D housings at volume, designers move to Al-Si cast alloys (A380/ADC12/AlSi10Mg). Use this matrix to choose:
Process decision matrix
| Criteria | 6061/6063 Extrusion | CNC from 6061 Plate/Bar | Al Die Casting (A380/ADC12/AlSi10Mg) |
|---|---|---|---|
| Geometry | Linear profiles, constant cross-section | Any 3D shape (machinable) | Complex 3D, thin walls, ribs, bosses |
| Tolerance | Good after straightening & machining | Excellent | Good; machine datums post-cast |
| Cosmetic finish | 6063 best for bright anodize | Good after finishing | Very good with shot/polish + coating |
| Tooling cost | Low (dies are simple) | None | High (molds), amortized at volume |
| Per-part cost @ volume | Low–mid | High | Low at medium–high volume |
| Lead time | Fast | Fast | Medium after tooling |
| Typical alloys | 6061-T6/T651, 6063-T5/T6 | 6061-T651 | A380 / ADC12 / AlSi10Mg |
Can 6061/6063 be die cast—wrought vs cast explanation
No. They’re wrought alloys (rolled/extruded/forged). Die casting needs fluid, shrink-tolerant Al-Si chemistries. If you’re prototyping a housing in machined 6061 or a 6063 extrusion assembly, we can translate the design to A380/ADC12/AlSi10Mg for mass production and hold critical features with post-machining.
How we integrate extrusions with die-cast housings
We often build mixed assemblies: 6061/6063 extrusions + A380/ADC12/AlSi10Mg housings.
- Joining options
- Bolted joints with steel inserts in castings; thread-forming screws for bosses.
- Bonding (structural acrylic/epoxy) for peel-resistant joints; prep by light blast + solvent clean.
- Weld only where needed; weld extrusion-to-extrusion, then mechanically fasten to the casting.
- Tolerance strategy
- Put datums on the machined extrusion; design locating pads into the casting.
- Use slots/ovals to accommodate thermal expansion mismatches.
- Corrosion control
- Anodize the extrusion; conversion coat/paint the casting.
- Use isolation washers/shims to manage galvanic couples.
Property by temper—typical behavior
| Alloy | Temper | Strength | Elongation | Weldability | Formability | Surface finish |
|---|---|---|---|---|---|---|
| 6061 | T6/T651 | High | Medium | Good | Fair–Good | Good (functional anodize, hardcoat) |
| 6063 | T5 | Medium-Low | High | Good | Very good | Excellent (bright anodize) |
| 6063 | T6 | Medium | Medium | Good | Good | Excellent |
(Use supplier datasheets for exact values on your drawings.)
Spec checklist for RFQs
- Alloy + temper (e.g., 6063-T5 vs 6063-T6; 6061-T6 vs T651)
- Profile drawing with wall thickness, corner radii, straightness/bow
- Cut length & machining ops (holes, threads, slots)
- Finish: anodize type/color/thickness or powder coat
- Critical datums & tolerances, flatness/parallelism for 6061 plate parts
- Packaging & inspection (CMM points, certificates)
FAQs — quick answers
- Which is stronger? 6061 (especially T6/T651).
- Which bends better? 6063.
- Which welds better? Both; pick 4043 for crack resistance, 5356 for strength and color match.
- Best for bright anodize? 6063.
- Can 6061/6063 be die cast? No—choose A380/ADC12/AlSi10Mg for die casting.
- Can I start in extrusion then switch to die casting? Yes—prototype in 6061/6063, then we optimize for Al-Si die casting and keep critical features by post-machining.
Need help deciding? Share your drawing and expected volume. We’ll recommend 6061, 6063, or a die-cast alternative with DFM notes, joining method, and finishing stack that fits your budget and timeline.
