Term and specification guide
6063 T5 vs T6 Aluminum: What the Temper Label Means
The difference between 6063-T5 and 6063-T6 for window profiles, with sourced reference values and the checks a buyer should add.
Decision summary. T5 and T6 are temper conditions, not brand names. Published reference values show higher minimum strength for T6, but the right choice depends on the structural requirement, the profile and the applicable standard. A listing label is not a mill certificate.
How the Component Works
Temper describes the heat-treatment or strain-hardening condition of the alloy. For 6063 extrusions, T5 and T6 are common designations. The temper changes the minimum mechanical properties the material is expected to meet; it does not change the alloy family or the profile geometry.
A higher-strength temper is not automatically the right choice for every window. The structural design, the profile section, the connection details and the applicable product standard determine what is required. The buyer's job is to make the requirement explicit and to match it to a certificate for the actual lot.
Terms You May See in Supplier Listings
Listings may show "6063", "6063-T5", "6063-T6", "T5/T6 available" or no temper at all. They may also use the spelling "aluminium". The alloy and temper should be read together with the wall thickness, the profile system and the certificate.
Material and Temper Labels
"6063" identifies the alloy family, not a strength grade. T5 and T6 are different tempers with different minimum properties. "T6 available" is not a specification for the delivered lot. Ask which temper is quoted, whether it is guaranteed in the mill certificate and whether the supplier will accept the certificate as a delivery document.
Measurements and Test Evidence
The table below reproduces reference values from the cited encyclopedia summary. They are not a substitute for the applicable standard or the supplier's mill certificate. Note the thickness condition: the values are stated for material up to 13 mm thick, and different thicknesses or product standards can change the acceptance values.
| Property | 6063-T5 | 6063-T6 |
|---|---|---|
| Minimum ultimate tensile strength, thickness up to 13 mm | 140 MPa | 190 MPa |
| Minimum yield strength, thickness up to 13 mm | 97 MPa | 160 MPa |
| Elongation in the cited reference | 8% | 8% at 3.15 mm or less; 10% in thicker sections |
What to Ask a Foshan Supplier
Ask for the alloy and temper in the quotation, the applicable standard, the mill certificate for the lot and the wall thickness at the critical points. Ask whether the supplier will accept a third-party mechanical test if the project requires one. If the answer is only "6063", ask for the missing temper before comparing price.
Common Misunderstandings
The following corrections follow from the reference values and their limits.
- T6 is always the better choice
- What is misleading: Higher minimum strength is not automatically required, and formability or other properties may differ.
How to check: Start from the structural requirement and the applicable standard, then specify the temper that meets it. - A listing that says T6 guarantees the delivered lot
- What is misleading: The label may describe an option rather than the material actually supplied.
How to check: Require the temper on the quotation, the mill certificate and the lot marking. - Temper alone determines window strength
- What is misleading: Profile geometry, wall thickness, reinforcement, connections and glass also contribute.
How to check: Assess the complete profile and assembly against the project requirement.
Sources, Methodology and Research Limits
This page separates published source material from editorial recommendations. Supplier descriptions are treated as claims, not as verified capabilities. The research record below lists what was checked for 6063 T5 vs T6.
Claims used on this page
public sourceverified6063 is described as the most common alloy used for aluminium extrusion and is used for window and door frames; it is heat treatable and suitable for anodizing.
6063 aluminium alloy — Lead section and Uses section
Limits: Encyclopedia summary; alloy selection depends on the structural requirement and applicable standard; Other alloys such as 6061 or 6082 may be specified where higher strength is needed.
public sourceverifiedFor 6063 material up to 13 mm thick, published reference values give minimum ultimate tensile strength of 140 MPa for T5 and 190 MPa for T6, and minimum yield strength of 97 MPa for T5 and 160 MPa for T6.
6063 aluminium alloy — Mechanical properties, 6063-T5 and 6063-T6
Limits: Values are quoted from an encyclopedia summary of secondary sources, not from a mill certificate or the governing standard; Thickness, temper practice and the applicable product standard change the acceptance values; Do not use these figures as purchase acceptance limits without the cited standard.
analysisverifiedWindow and door frames are listed applications of 6063 aluminum extrusions; profile geometry, alloy, temper and wall thickness are separate variables.
6063 aluminium alloy — Uses section
Extrusion — Materials, aluminum
Limits: The sources establish general application, not the suitability of a particular profile for a particular window system; Wall thickness alone is not a quality verdict.
Sources
- 6063 aluminium alloy. Wikipedia. Reference report. Accessed 10 November 2026.
What it supports: Overview of 6063 alloy composition, common extrusion use, window and door frame applications, and published T5 and T6 mechanical property values.
Limits: Encyclopedia summary of secondary sources, not the Aluminum Association standard itself; Property values depend on thickness, temper condition and product standard; they cannot be used as acceptance limits without the applicable specification. - Extrusion. Wikipedia. Reference report. Accessed 10 November 2026.
What it supports: General explanation of extrusion, die cross-sections, hot extrusion and aluminum as a commonly extruded material.
Limits: Encyclopedia overview, not an extrusion tolerance or alloy standard; Process temperatures and equipment descriptions are general and not supplier-specific.
Research limits
- Reference values are quoted from an encyclopedia summary, not from the governing standard or a mill certificate.
- The values apply to a stated thickness range and cannot be used as acceptance limits for an arbitrary order.
- No mechanical test was performed for this edition.
- Property values are secondary-source reference values.
- No order-specific acceptance limit is provided.
Exclusions: Mechanical testing.; Standard text review.; Supplier certificates..