If you are sourcing aluminum profiles for a building project, an industrial frame, or any extruded component, you will quickly encounter two alloys: 6061 and 6063. Both belong to the 6xxx series — aluminum-magnesium-silicon alloys that respond to heat treatment and extrude well. Both are widely available and competitively priced.
But they are not interchangeable. 6063 is the first choice for architectural profiles, window frames, and decorative applications where surface quality matters. 6061 is the right call when structural strength, machinability, or load-bearing capacity is the priority.
This guide compares 6061 and 6063 aluminum across all the dimensions that affect real project decisions: mechanical properties, temper designations, extrudability, anodizing performance, applications, price, and a quick decision framework you can use right now.
The global aluminum extrusion industry relies heavily on 6xxx-series alloys. Within that family, 6063 accounts for roughly 65% of all extrusion volume worldwide, with 6061 contributing around 20%. Together, they cover the vast majority of commercial and industrial applications.
Both alloys share the same fundamental chemistry: aluminum as the base, magnesium for strength, and silicon to improve fluidity during extrusion and allow heat treatment. The differences lie in the ratios. 6061 carries more magnesium and silicon, which pushes its strength higher but makes it harder to extrude into complex shapes. 6063 uses lower alloy content, which makes it easier and faster to extrude — but leaves it with lower mechanical strength.
The practical result: 6063 is optimized for appearance and formability; 6061 is optimized for load and performance. Understanding where your project falls on that spectrum is the key to choosing the right alloy.
The table below compares the two alloys across the properties that matter most for extrusion and structural decisions. Values shown are for the most common tempers: 6061-T6 and 6063-T6 or T5.
Property | 6061-T6 | 6063-T6 / T5 |
Tensile strength | 310 MPa (45 ksi) | 241 MPa T6 / 186 MPa T5 |
Yield strength | 276 MPa (40 ksi) | 214 MPa T6 / 145 MPa T5 |
Brinell hardness | 95 HB | 73 HB T6 / 60 HB T5 |
Elongation at break | 8–10% | 8–12% |
Density | 2.70 g/cm³ | 2.69 g/cm³ |
Mg content | 0.8–1.2% | 0.45–0.9% |
Si content | 0.4–0.8% | 0.2–0.6% |
Fe content (max) | 0.7% | 0.35% — lower = finer grain |
Thermal conductivity | 151–167 W/m·K | 190–201 W/m·K |
Extrudability | Moderate — thicker walls | Excellent — thin & complex |
Min. wall thickness | ~1.5 mm typical | ~0.8–1.0 mm achievable |
Anodize quality | Good — slight streaking possible | Excellent — uniform, bright |
Weldability | Good (MIG/TIG, ER4043) | Good (MIG/TIG, ER4043) |
HAZ strength loss | Significant in T6 | Moderate in T6 |
Machinability | Excellent | Good |
Heat-treatable | Yes (T4, T6, T6511) | Yes (T5, T6, T52) |
Relative cost | Slightly higher | Slightly lower |
A few numbers stand out. First, the strength gap: 6061-T6 delivers 310 MPa tensile strength versus 241 MPa for 6063-T6 and only 186 MPa for 6063-T5. For structural applications with defined load requirements, this difference is significant. Second, thermal conductivity: 6063 conducts heat better (201 W/m·K vs 151–167 W/m·K for 6061), which is why it dominates LED heat sink manufacturing. Third, the iron content difference: 6063 caps iron at 0.35%, compared to 0.7% for 6061. Lower iron means finer grain structure — and that finer grain is what gives 6063 its superior anodizing performance.
The letter-number code after the alloy number describes the heat treatment applied after extrusion. Specifying the correct temper is as important as specifying the correct alloy — the same alloy in a different temper can have dramatically different properties.
• 6063-T5: The most widely used temper for architectural profiles. The profile is cooled directly from the extrusion press (air-cooled), then artificially aged. Tensile strength reaches 186 MPa. Used for window frames, door frames, curtain wall, and most decorative profiles where high strength is not required.
• 6063-T6: Solution heat-treated after extrusion, then artificially aged. Tensile strength rises to 241 MPa — a 30% increase over T5. Used where 6063 must carry more load, such as structural glazing frames and heavier mullions.
• 6063-T52: Stress-relieved by stretching after quench. Minimizes residual stresses in the profile. Used for profiles that will be machined to tight tolerances after extrusion.
• 6061-T6: The industry-standard temper. Solution heat-treated and artificially aged to peak strength (310 MPa). The most common specification for structural, industrial, and aerospace ground-support applications. This is the temper behind the high search interest in 6061 T6 pricing and specifications.
• 6061-T4: Naturally aged after solution heat treatment. Lower strength than T6 (around 241 MPa) but significantly better ductility. Used when cold-forming operations are required before final heat treatment.
• 6061-T6511: Solution heat-treated, stretched to relieve stress, then artificially aged. The stretch eliminates internal stress gradients, producing profiles with excellent dimensional stability for precision machining applications.
When specifying material, always state both the alloy and the temper. A purchase order for '6063 aluminum' without a temper designation leaves the supplier to ship T5 by default — which may or may not be what your design requires.
6063 became the dominant architectural aluminum alloy for straightforward reasons: it extrudes into the complex hollow shapes that building components require, it anodizes beautifully, and it carries enough strength for non-structural facade applications at a cost that works for large-scale projects.
This is the single largest application for 6063 globally. Window profiles typically require multiple internal chambers (for thermal breaks, drainage, and glazing retention), thin walls, and tight dimensional tolerances — all areas where 6063's extrudability gives it a clear advantage over 6061. The T5 temper is standard. After extrusion, frames are typically anodized or powder-coated for weather resistance.
Curtain wall mullions and transoms use 6063-T5 or T6 depending on wind load and span requirements. These profiles combine multiple functions in a single extrusion: structural, weatherproofing, and aesthetic. The design flexibility that 6063 provides — walls as thin as 0.8 mm, complex multi-chamber sections — is not achievable with 6061 at commercial extrusion speeds.
Handrails, partition frames, ceiling grid systems, and decorative trims all use 6063. The alloy's consistent, fine-grained surface takes anodizing uniformly. A clear anodize on a 6063 profile produces a bright, transparent finish. The same treatment on 6061 often shows faint streaking from its higher iron and silicon content — acceptable in industrial settings, but not ideal for high-visibility architectural installations.
Photovoltaic panel frames are one of the fastest-growing applications for 6063. The alloy's combination of corrosion resistance, extrudability, and moderate strength covers the structural requirements of most residential and commercial solar installations. The 6063-T5 temper is the global industry standard for this application.
6063's thermal conductivity of approximately 201 W/m·K — about 25% better than 6061's 151–167 W/m·K — makes it the preferred alloy for extruded heat sinks used in LED lighting, power electronics, and telecommunications equipment. The ability to extrude dense fin arrays with thin walls compounds this advantage.
When the design is driven by load tables, structural codes, or mechanical performance rather than appearance, 6061-T6 is typically the correct specification. Its 310 MPa tensile strength is approximately 30% higher than 6063-T6 and nearly 70% higher than 6063-T5. For applications where cross-section size is constrained by weight or space, that strength difference translates directly into thinner, lighter profiles.
Warehouse racking, conveyor frames, machine guarding, and equipment enclosures commonly use 6061-T6 extruded tubes and channels. The alloy handles point loads, dynamic loads, and fastener pull-out forces that 6063 would not meet without significantly increasing the profile's wall thickness.
Structural aluminum railings and walkway gratings designed to building or bridge codes specify 6061-T6. The alloy satisfies the yield-strength minimums required by standards such as AASHTO and Eurocode 9 for load-bearing handrail and guard rail systems.
6061 machines exceptionally well. It holds tight tolerances and produces clean chip formation, which reduces tool wear and machining time. Hydraulic fittings, valve bodies, pneumatic components, and structural connectors are frequently machined from 6061-T6511 bar or extruded shapes.
6061-T6 is one of the alloys listed in US military specifications for structural aluminum components. It appears in aircraft ground-support equipment, armored vehicle fittings, and general defense-sector structural parts — a recognition of its dependable combination of strength, corrosion resistance, and machinability.
Many real-world structures use both alloys strategically. A common approach in curtain wall construction: 6061-T6 for the primary structural steel-replacement members that carry wind and gravity loads, and 6063-T5 for the facing profiles, caps, and covers that define the building's appearance. Each alloy does what it does best, and the assembly performs better than either alloy alone.
Application | Best alloy | Key reason |
Window & door frames | 6063-T5 | Complex hollow sections, anodize quality, cost |
Curtain wall systems | 6063-T5 / T6 | Thin walls, tight tolerances, surface finish |
Glazing beads & mullions | 6063-T5 | Surface quality critical, minimal load |
Interior trims & handrails | 6063-T5 | Decorative anodize, easy forming |
Solar panel frames | 6063-T5 | Lightweight, weather resistance, cost |
LED heat sinks | 6063 | Superior thermal conductivity (201 W/m·K) |
Industrial racking & frames | 6061-T6 | High load capacity, ~30% stronger than 6063 |
Bridge railings & walkways | 6061-T6 | Structural code compliance |
Mechanical connectors & fittings | 6061-T6 | Machinability, dimensional precision |
Truck & trailer components | 6061-T6 | Impact resistance, fatigue strength |
Marine deck equipment (above waterline) | 6061-T6 | Structural load, non-immersed |
Mixed arch. + structural | 6063 (facade) + 6061 (frame) | Optimize aesthetics and strength |
Anodizing is an electrochemical process that converts the aluminum surface into a hard, porous aluminum oxide layer. The finish protects against corrosion and wear, and it can be dyed to virtually any color. For architectural applications, anodize quality is often as important as mechanical properties.
6063 consistently produces superior anodize results. The reason is microstructural: 6063's lower iron content (max 0.35%) results in fewer intermetallic particles at the grain boundaries. These particles are the main cause of the subtle streaking and banding that can appear on anodized 6061 profiles. With fewer particles, the anodize film grows more uniformly across the 6063 surface, producing a brighter, more transparent finish.
For clear anodize (AA15 class, 15-micron film thickness standard in architectural applications), 6063-T5 or T6 is the correct specification. Dyed anodize shows more consistent color on 6063 as well, since the dye uptake is uniform across the surface.
6061 anodizes acceptably for industrial and non-appearance-critical applications. The streaking effect is subtle and may not be visible at normal viewing distances, particularly with colored anodize or powder coat. If the profile will be powder-coated rather than anodized, the alloy difference in surface quality is largely irrelevant — both perform well under paint.
Extrudability describes how readily an alloy flows through a die at a given press speed and temperature. It affects what shapes are achievable, what minimum wall thicknesses are possible, and what the manufacturing cost will be.
6063 is significantly more extrudable than 6061. Its lower alloy content means the billet generates less heat during extrusion, allowing the press to run at higher speeds — typically 30 to 50% faster than 6061 — without overheating the profile. Higher press speed translates directly into lower manufacturing cost per kilogram of finished profile.
The minimum achievable wall thickness reflects this difference. 6063 can reliably achieve walls as thin as 0.8 to 1.0 mm, enabling the dense thermal fins in heat sinks and the multi-chamber window profiles that define modern architectural aluminum. 6061 typically requires walls of at least 1.5 mm, which limits the complexity of achievable cross-sections.
Die longevity is another factor. 6063 is softer and less abrasive, so extrusion dies last longer before requiring refurbishment. On a large run, this reduces tooling cost per kilogram of output.
The practical conclusion: if your cross-section design includes thin walls (under 1.5 mm), multiple internal voids, or complex hollow chambers, 6063 is the right material choice. If the section is simpler — solid or single-hollow — and strength is the governing requirement, 6061 is appropriate.
Both alloys are among the most cost-competitive options in the aluminum extrusion market. The raw material price difference between them is modest — 6063 typically costs slightly less than 6061 because it uses lower quantities of magnesium and silicon.
However, raw material is rarely the largest cost driver in an extruded aluminum purchase. The factors that actually determine the final price per kilogram are:
• Profile complexity: A simple solid bar is far cheaper to extrude than a multi-chamber hollow profile, regardless of alloy. Complex dies cost more to produce and maintain, and press speeds are lower.
• Wall thickness and weight per meter: Thinner walls mean less aluminum per meter of profile. 6063's ability to achieve thinner walls can actually reduce material cost per linear meter even if the per-kilogram alloy price were identical.
• Temper: T6 costs more than T5 because it requires an additional solution heat-treatment step (quenching). For 6061, T6 involves significant additional processing versus T4.
• Order quantity: Minimum order quantities (MOQ) and the amortization of die costs across the run volume have a larger impact on unit price than alloy selection for most buyers.
• Surface treatment: Anodizing and powder coating are priced separately from the base extrusion. These can equal or exceed the base profile cost for complex finishes.
• Certification requirements: If DNV, ABS, or other third-party material certifications are required (uncommon for standard construction profiles, but required in marine and aerospace contexts), they add cost regardless of alloy.
For a realistic price comparison, the most useful approach is to request quotes for your specific cross-section in both alloys. The differences in extrusion speed and die behavior often offset the raw material premium, and the real cost comparison only becomes clear with your actual part geometry.
Contact our sales team with your profile drawing, required alloy and temper, surface treatment, and target quantity. We will respond with pricing and lead time within 24 hours.
Use the following criteria to select the right alloy before requesting a quote.
• The profile is a window frame, door frame, curtain wall component, or architectural facade element
• Surface appearance is critical and the finish will be clear anodize or dyed anodize
• The cross-section includes thin walls (under 1.5 mm), multiple internal chambers, or complex hollow geometry
• The application is non-structural or lightly loaded — decorative, weatherproofing, or thermal separation
• The profile is a solar panel frame or LED heat sink where thermal conductivity matters
• Cost per kilogram is a primary driver and strength requirements are moderate
• The profile is architectural but carries more load — structural glazing mullions, heavier curtain wall frames
• You need 6063's anodizing quality but with 30% more strength than T5
• The profile carries structural loads defined by engineering calculations or building codes
• The application involves mechanical connections, fasteners under load, or impact exposure
• The profile will be machined after extrusion and dimensional stability is critical
• The end use is industrial, transportation, military, or aerospace ground support
• Appearance is secondary and the profile will be painted, powder-coated, or left mill-finish
Use 6061-T6 for primary structural members that carry wind or gravity loads. Use 6063-T5 for the visible facing elements, caps, cover plates, and decorative profiles. This approach gives the assembly the structural performance of 6061 and the appearance quality of 6063 — without compromising either.
We supply both 6061 and 6063 aluminum extrusion in a full range of tempers: 6061-T4, T6, T6511 and 6063-T5, T6, T52. Stock profiles and custom extrusions are available.
• Custom cross-sections: provide your profile drawing and we will produce the extrusion die and manufacture to your specification
• Surface treatments: anodizing (clear and dyed, AA10 to AA25 class), powder coating, and wood-grain sublimation transfer available in-house
• Mill Test Certificates (MTC) provided with every shipment for full material traceability
• Established export experience across Southeast Asia, the Middle East, Europe, and the Americas
• Fast RFQ response: submit your alloy, temper, cross-section drawing, length, and quantity and we will reply within 24 hours with pricing and lead time
Contact us today for a quote. Whether you are specifying profiles for a curtain wall system, an industrial frame, or a solar mounting structure, we have the alloy, temper, and surface treatment to meet your requirements.
