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6061 vs 6063 aluminum — and how to pick the rest
The alloy decides strength, corrosion resistance, thermal conductivity and how easily the part machines and finishes. The most-asked comparison is 6061 vs 6063; here is the full call, plus the other alloys we run.
6061 vs 6063 aluminum
The short version: both are 6xxx (Mg+Si) alloys that anodize well. 6061 is stronger and welds harder; 6063 finishes better and extrudes into thinner sections.
If you remember one rule: structural or heavily machined → 6061; thin, decorative or best-anodize extrusion → 6063. Heatsinks and enclosures split by need — many fin stacks use 6063 for surface finish, many frames use 6061 for stiffness. Neither is "better"; they trade strength for finish.
Which is stronger? 6061, clearly. In the common T6 temper, 6061 reaches roughly 310 MPa tensile against about 215 MPa for 6063 — the yield gap is similar. That is why 6061 carries load and 6063 carries appearance. Weldability is good in both (5356 or 4043 filler); 6061 loses a little more strength in the weld zone, which matters only in loaded welds. Cost is close; 6063 is often a touch cheaper because it extrudes faster and needs less correction.
| Property (T6, typical) | 6061 | 6063 |
|---|---|---|
| Tensile strength | ~310 MPa | ~215 MPa |
| Yield strength | ~276 MPa | ~170 MPa |
| Thermal conductivity | ~167 W/m·K | ~201 W/m·K |
| Anodize finish | Good | Excellent (brighter) |
| Extrudability (thin walls) | Fair | Very good |
| Weldability | Good | Good |
Values are typical for the T6 temper and vary with temper and supplier; confirm against the cert for your order.
Temper: T5 vs T6 (and T4)
The temper matters as much as the alloy number.
T6 is solution-heat-treated then artificially aged — maximum strength, the default for structural 6061. T5 is cooled from extrusion then aged, skipping the re-heat; it is slightly softer but has less distortion and lower cost, common for 6063 architectural sections. T4 is solution-treated but not aged, softer and formable — rare for our parts. If you specify only "6063", we default to T5 for finish; if you need strength, say T6.
The other alloys we run
When 6061/6063 are not the fit.
| Alloy | Strength | Corrosion | Typical use |
|---|---|---|---|
| 6082 | High | Good | EU structural (EN AW-6082); often specified on European drawings |
| 7075 | Very high | Fair | Aircraft, high-stress brackets; harder to anodize evenly |
| 1070 / 1060 | Low | Good | Pure-aluminum fin stock for skived heatsinks (max thermal conductivity) |
We stock and run the alloys your drawing calls for; tell us strength vs finish priority and we recommend the temper.
Aluminum vs copper for heatsinks
A quick note buyers ask for.
Copper conducts heat better but is heavier, dearer and harder to finish; aluminum is the default for most electronics because it is light, cheap and anodizes well. Choose copper only where peak conductivity outweighs cost and weight — for example a thin insert at a hot spot. Aluminum liquid cold plates and extruded fins cover most high-power needs.
Need help choosing?
- Strength vs finish priority → 6061 or 6063.
- EU projects often specify 6082.
- Pure thermal fins → 1070/1060 maximizes conduction.
- High-stress, weight-secondary → 7075.
Questions buyers ask first
Straight answers on alloy choice.
6061 vs 6063 — which is stronger?
6061 is stronger. In T6 temper, 6061 reaches about 310 MPa tensile against roughly 215 MPa for 6063, with a similar yield gap. That is why 6061 is used for structural and machined parts and 6063 for thin, decorative extrusions and enclosures. Pick 6061 when the section carries load; pick 6063 when finish and thin walls matter more than strength.
Should I specify T5 or T6?
Specify T6 when you need strength — it is heat-treated and aged for maximum properties, the default for 6061 structural parts. Choose T5 for 6063 architectural sections when you want lower distortion and cost and can accept slightly lower strength; T5 is the usual finish-grade temper. If your drawing just says "6063", we default to T5 unless strength is called out.
Can you anodize 6061?
Yes. 6061 anodizes well and gives a good, corrosion-resistant layer; 6063 simply takes a brighter, more uniform finish because it is cleaner and less alloyed. For a visible bright finish, 6063 is the easier choice; for a structural part that also needs anodizing, 6061 is fine. We match the process to the alloy and temper.
Which alloy for a heatsink?
For extruded fins, 6063 is common because it extrudes thin and finishes clean; for skived fins, pure 1070/1060 maximizes thermal conductivity. The base or cold-plate body is often 6061 or 6063 depending on whether it also carries load. Tell us the dissipation and we pick alloy and temper together with the fin method.
Not sure which alloy?
Send the application — we recommend alloy, temper and finish.