What Are T5 and T6? Aluminum Temper Codes and Their Differences

What Are T5 and T6? Aluminum Temper Codes and Their Differences

T5, T6, T4, and T1 are temper designations used for aluminum alloys to describe the metallurgical condition of the material after manufacturing and heat treatment processes. Especially in 6000 series aluminum alloys, the temper condition is an important parameter that affects mechanical properties, strength, hardness, and performance.

When purchasing an aluminum profile, it is not enough to look only at the alloy designation, such as 6060, 6061, 6063, or 6082. The same aluminum alloy can have different mechanical properties depending on its temper condition.

For this reason, both the alloy and temper designation should be considered when evaluating an aluminum profile or extrusion product.

For example:

• 6063-T5 → 6063 alloy, T5 temper
• 6061-T6 → 6061 alloy, T6 temper
• 6082-T6 → 6082 alloy, T6 temper

So, what do T5 and T6 mean? What is the difference between T5 and T6? Which one provides higher strength? Why is the temper designation important when selecting an aluminum profile?

In this article, we will examine aluminum temper designations and explain the differences between T5 and T6 in detail.

What Is Aluminum Temper?

Temper refers to the metallurgical condition of an aluminum product resulting from specific thermal and/or mechanical treatments applied during or after manufacturing.

Aluminum temper designations are used to indicate how a product has been heat-treated, aged, or mechanically processed.

The temper designation should be considered separately from the alloy designation.

For example, in 6063-T5:

• 6063 → identifies the aluminum alloy
• T5 → identifies the temper condition

The main aluminum temper groups include F, O, H, W, and T. The T temper group generally refers to products that have been thermally treated to produce a stable temper condition.

Especially in extruded aluminum profiles, designations such as T1, T4, T5, and T6 are commonly encountered.

The main difference between these tempers is the sequence of heat treatment and aging processes applied to the aluminum after extrusion or other high-temperature forming operations.

What Is T5?

T5 is an aluminum temper condition in which the material is cooled after a high-temperature shaping process, such as extrusion, and then artificially aged.

In simplified terms, the T5 production sequence can be represented as:

Extrusion → Cooling → Artificial Aging → T5

After extrusion, the profile exits the die at an elevated temperature. The profile is then cooled under controlled conditions and subsequently subjected to artificial aging in an aging furnace.

This process helps develop the desired mechanical properties of the alloy.

T5 temper is particularly common in extruded aluminum profiles.

What Is 6063-T5?

6063-T5 refers to an aluminum profile made from the 6063 alloy and brought to the T5 temper condition through artificial aging after the high-temperature forming process.

6063 is one of the 6000 series aluminum alloys widely used for extrusion applications.

It is commonly encountered in applications such as architectural profiles, door and window systems, and various extruded aluminum products.

However, whether a particular 6063-T5 profile is suitable for a specific application should not be determined solely by its alloy and temper designation. Profile geometry, wall thickness, mechanical properties, applicable standards, and other technical requirements should also be considered.

What Is T6?

T6 is an aluminum temper condition obtained through solution heat treatment followed by artificial aging.

A simplified T6 process can be represented as:

Solution Heat Treatment → Quenching/Cooling → Artificial Aging → T6

During the T6 treatment, the alloy is first heated to an appropriate temperature for solution heat treatment. It is then rapidly cooled or quenched under controlled conditions and subsequently artificially aged.

For heat-treatable aluminum alloys, this process can significantly improve mechanical strength through precipitation hardening.

What Is 6061-T6?

6061-T6 refers to 6061 aluminum alloy in the T6 temper condition.

6061 is one of the widely used 6000 series aluminum alloys and is used in various engineering applications where mechanical properties are important.

What Is 6082-T6?

6082-T6 refers to 6082 aluminum alloy in the T6 temper condition.

6082 is another 6000 series aluminum alloy commonly used where relatively high mechanical strength is required.

Therefore, in the designation 6082-T6:

• 6082 identifies the alloy
• T6 identifies the temper condition

What Is the Difference Between T5 and T6?

The main difference between T5 and T6 is the heat treatment route used to achieve the final temper condition.

An important point is that T6 does not automatically mean “better” than T5 in every application.

T5 and T6 describe different treatment routes. The appropriate temper depends on the alloy, profile geometry, required mechanical properties, applicable standards, and intended application.

Therefore, temper selection should not be based simply on which designation sounds stronger.

Is T5 or T6 Stronger?

This is one of the most frequently asked questions when purchasing aluminum profiles.

However, it is not technically correct to make a universal strength ranking for all aluminum alloys based only on the temper designation.

Different temper conditions of the same alloy can have different mechanical properties. However, the actual results depend on:

• alloy composition,
• product geometry,
• cross-sectional dimensions,
• wall thickness,
• heat treatment conditions,
• aging conditions,
• applicable product standards.

For example, comparing 6063-T5 and 6061-T6 is not simply a comparison between T5 and T6 because the alloy is also different.

A proper comparison should consider mechanical properties such as:

• tensile strength,
• yield strength,
• elongation,
• hardness.

These values should be evaluated according to the relevant product standard or technical specification.

What Is Artificial Aging?

Understanding artificial aging is important when explaining both T5 and T6 tempers.

Artificial aging is a controlled heat treatment in which an aluminum alloy is held at a specific temperature for a specified period to develop its mechanical properties.

In 6000 series aluminum alloys, the presence of magnesium and silicon allows suitable alloys to respond to precipitation hardening through appropriate heat treatment and aging.

In simplified terms:

Heat Treatment + Controlled Aging → Improved Mechanical Properties

For optimum results, however, temperature, time, and cooling conditions must be controlled according to the alloy and product.

What Is Solution Heat Treatment?

Another important concept for understanding T6 is solution heat treatment.

During solution heat treatment, the alloy is heated to an appropriate temperature so that alloying elements can dissolve into the aluminum solid solution.

The material is then rapidly cooled or quenched to retain the desired metallurgical condition.

Artificial aging is subsequently applied.

The simplified T6 process is:

Heating → Solution Heat Treatment → Quenching → Artificial Aging

For suitable alloys, this process enables precipitation hardening and the development of higher mechanical properties.

T5 and T6 in Aluminum Extrusion

In aluminum extrusion, the selected temper is important for achieving the required mechanical properties.

During extrusion, the aluminum billet is heated and forced through a die to produce the desired profile cross-section.

The profile can then pass through production stages such as:

Billet → Heating → Extrusion → Cooling → Stretching → Cutting → Aging

For T5 temper, the extruded product is cooled and then artificially aged.

For T6 temper, the product undergoes solution heat treatment followed by artificial aging according to the requirements of the T6 temper.

Proper control of temper conditions during extrusion production is important for ensuring that the final mechanical properties meet the specified requirements.

T5 and T6 in 6000 Series Aluminum Alloys

T5 and T6 are particularly common temper designations for 6000 series aluminum alloys.

Examples include:

• 6060-T5
• 6060-T6
• 6061-T6
• 6063-T5
• 6063-T6
• 6082-T6

These designations are frequently encountered in the aluminum extrusion industry.

6000 series alloys are magnesium-silicon-based alloys that can develop improved mechanical properties through appropriate heat treatment.

However, not every alloy is used in every temper condition in the same way. Therefore, during technical purchasing processes, it is important to evaluate the alloy + temper + product standard + mechanical properties together.

Why Are T5 and T6 Important When Selecting an Aluminum Profile?

When purchasing an aluminum profile, it is important to consider more than just dimensions and price per kilogram.

The temper condition is also an important part of the product's technical specification.

The temper designation becomes particularly important when:

1. Mechanical Strength Is Important

If the profile is expected to carry a load or withstand specific mechanical forces, its temper condition should be considered.

2. A Technical Specification Is Required

A project or customer specification may require a particular alloy and temper.

For example, a specification may state 6063-T5 or 6061-T6.

3. Compliance With Standards Is Required

The mechanical properties of aluminum products should be evaluated according to the relevant standards. The temper designation is an important part of this technical evaluation.

4. Product Performance Matters

Products made from the same alloy can have different mechanical properties depending on their temper condition.

Therefore, simply stating “6063 aluminum profile” may not always provide sufficient technical information.

What Is the Difference Between Alloy and Temper?

These two concepts are often confused.

Alloy refers to the chemical composition and alloy designation of the aluminum.

Temper refers to the metallurgical condition resulting from the thermal and/or mechanical treatments applied to the product.

For example:

6063-T5

6063: Aluminum alloy

T5: Temper condition achieved by cooling after a high-temperature forming process and subsequent artificial aging

Another example:

6082-T6

6082: Aluminum alloy

T6: Temper condition achieved through solution heat treatment and artificial aging

Therefore, it is not technically correct to say that “T5 is an aluminum alloy” or “T6 is an aluminum alloy.”

T5 and T6 are temper designations.

Difference Between T5, T6, T4, and T1

Several temper conditions may be encountered in 6000 series aluminum products.

These descriptions provide a general explanation of the temper system. The final mechanical properties of a specific product should always be evaluated according to the relevant alloy and product standard.

How Do You Read an Aluminum Material Designation?

When reading an aluminum material designation, the alloy should be identified first, followed by the temper designation.

For example:

6063-T5

6063: Aluminum alloy

T5: Cooled after a high-temperature forming process and artificially aged

6061-T6

6061: Aluminum alloy

T6: Solution heat-treated and artificially aged

6082-T6

6082: Aluminum alloy

T6: Solution heat-treated and artificially aged

Therefore, in technical quotations, purchase orders, and product specifications, it is important to specify the alloy and temper together when required.

What Information Should Be Included When Ordering an Aluminum Profile?

When purchasing an aluminum profile or billet, providing the correct technical specification makes it easier to compare quotations and ensure that production is carried out according to the required specifications.

Depending on the product, the following information may be specified:

• Aluminum alloy
• Temper
• Profile or cross-sectional dimensions
• Wall thickness
• Length
• Surface finish
• Mechanical property requirements
• Applicable standard
• Tolerances
• Packaging requirements
• Quantity

For example, a technical request may specify:

6063-T5 aluminum extrusion profile

Specifying the alloy and temper together provides a clearer technical definition of the required material.

Frequently Asked Questions About T5 and T6 Aluminum

What does T5 mean in aluminum?

T5 is a temper condition in which aluminum is cooled after a high-temperature forming process and subsequently artificially aged.

What does T6 mean in aluminum?

T6 is a temper condition in which aluminum undergoes solution heat treatment followed by artificial aging.

Is T5 or T6 stronger?

It is not technically correct to establish a universal strength ranking for all aluminum alloys based only on the temper designation. Mechanical properties should be evaluated according to the alloy, product geometry, and applicable standard.

What does 6063-T5 mean?

6063-T5 refers to 6063 aluminum alloy in the T5 temper condition. It is a commonly encountered designation for extruded aluminum profiles.

What does 6061-T6 mean?

6061-T6 refers to 6061 aluminum alloy in the T6 temper condition, which involves solution heat treatment followed by artificial aging.

What is the main difference between T5 and T6?

The main difference is the heat treatment route. T5 refers to cooling after a high-temperature forming process followed by artificial aging, while T6 refers to solution heat treatment followed by artificial aging.

Why is the aluminum temper designation important?

The temper designation indicates the metallurgical condition of the aluminum product and is an important technical parameter when evaluating its mechanical properties.

Conclusion

T5 and T6 are two commonly encountered aluminum temper designations, particularly in extruded aluminum products.

T5 refers to products that are cooled after a high-temperature forming process and subsequently artificially aged, while T6 refers to products that undergo solution heat treatment followed by artificial aging.

Therefore, designations such as 6063-T5, 6061-T6, and 6082-T6 provide information about both the aluminum alloy and its temper condition.

When selecting an aluminum profile, the appropriate temper should not be determined simply by asking “T5 or T6?” Instead, the alloy, mechanical properties, profile geometry, operating conditions, and applicable technical standards should be evaluated together.

As Biser Aluminium, we supply aluminum billets and extrusion profiles in different alloys and temper conditions and evaluate technical requirements to help determine product specifications suitable for your project.