Aluminium Tempers Designations Explained: What F, O, H and T Really Mean

TL;DR: Aluminium temper tells you how the metal was treated after it was made. It is important because it changes how strong, hard, or bendable the metal is. Even if two pieces are the same alloy, different tempers mean they will act differently.

Tempers use letters like O for soft, H for strain-hardened, and T for heat-treated. For example, 6061-T6 is a common strong alloy used for structures, while O tempers are better for bending and shaping. Picking the wrong temper can lead to cracking or parts that are too weak for the job. Always check both the alloy and the temper before you buy.

Aluminium temper sounds technical. But it’s not complicated.

Temper simply tells you how aluminium was processed after it was made, and what that means for strength, formability, and use.

This guide explains aluminium temper and temper designations in simple terms. It also shows how heat treatment changes common aluminium alloys like 6061 aluminium, 7075 aluminium, and 5052 aluminium sheet.

What is Aluminium Temper?

Aluminium temper describes the combination of heat treatment and mechanical work applied after the metal is produced.

Temper affects:

• Strength
• Hardness
• Ductility
• Corrosion behaviour
• Suitability for forming or machining

Temper designations use letters and numbers. The letter tells you the processing method. The numbers add detail.

A 6061 aluminium sheet in O temper behaves nothing like 6061 T6 aluminium. Same alloy. Totally different use.

The Five Basic Temper Types

All aluminium tempers fall under five main letters. Everything else is a variation of these.

1. F temper – as fabricated

This is aluminium in its basic manufactured state.

• No controlled heat treatment
• No controlled cold working
• Properties can vary

Used when strength is not critical or when the material will be processed further.

Typical uses:

• As-cast products
• Early-stage extrusions
• Semi-finished material

2. O temper – as annealed

This is fully softened aluminium.

• Maximum ductility
• Lowest strength
• Easy to bend, draw, or form

Used where shaping is more important than strength.

Typical uses:

• Foil
• Deep-drawn cookware
• Formed sheet products

3. H temper – strain hardened

This applies only to non-heat-treatable aluminium alloys like 1xxx, 3xxx, and 5xxx series.

Strength comes from cold working, not heat treatment.

H tempers are written as H followed by two digits.

The first digit shows how it was treated:

• H1: strain hardened only
• H2: strain hardened and partially annealed
• H3: strain hardened and stabilised

The second digit shows the hardness level:

• 2: quarter hard
• 4: half hard
• 6: three-quarter hard
• 8: full hard

Example: H14 means strain hardened and half hard.

Typical uses:

• Roofing sheets
• Beverage can stock
• Automotive panels
• Marine-grade sheets

4. T temper – heat-treated

This applies only to heat-treatable aluminium alloys like 2xxx, 6xxx, and 7xxx series.

Strength comes from controlled heat treatment and ageing.

Common T tempers you’ll see in the market:

• T1: Cooled after hot forming, then allowed to age naturally
• T2: Cooled after hot forming, then cold worked and naturally aged
• T3: Solution heat-treated, then cold-worked and naturally aged
• T4: Solution heat-treated, then naturally aged
• T5: Cooled after hot forming, then artificially aged
• T6: Solution heat-treated, then artificially aged
• T7: Solution heat-treated, then over-aged for stability
• T8: Solution heat-treated, then cold-worked and artificially aged
• T9: Solution heat-treated and artificially aged, then cold worked
• T10: Cooled after hot forming, then cold worked and artificially aged

T6 is the most common and most specified temper in structural aluminium.

Typical uses:

• Extrusions
• Automotive parts
• Structural profiles
• Aerospace components

If you want the quote for any of these products, you can fill out our RFQ form and we’ll match you with multiple sellers who can share quotes with you.

Other: W temper – solution heat treated

This is a temporary condition.

• Material is freshly solution heat-treated
• Properties change with time
• Rarely sold or specified

Used mainly in labs or controlled production environments.

How to Read an Aluminium Temper?

A full aluminium designation looks like this: 6063-T6 or 5052-H32

Here’s how to read it:

• The alloy number tells you the chemistry
• The temper tells you the processing
• Together, they define performance

Important rule:

Not every temper works with every alloy.

For example:

• 6063-H14 is wrong
• 3003-T6 is wrong

If you see this in a listing or datasheet, that’s a red flag.

How Temper Impacts Real-world Use?

Temper selection affects cost, performance, and failure risk.

If the temper is too hard:

• Cracking during bending
• Poor formability
• Higher scrap rate

If the temper is too soft:

• Low load capacity
• Deformation in service
• Shorter product life

This is why buyers should always ask for alloy plus temper, not just aluminium alloy.

Common Examples of Aluminium Alloy Tempers and Applications

Common Mistakes Seen in Product Listings

These come up often in aluminium buying and selling platforms.

Using H temper for 6xxx alloys
Using T temper for 3xxx or 5xxx alloys
Calling hardness a temper
Copy-pasting tempers without checking standards

If you’re sourcing aluminium, don’t ignore this. You can get in touch with us at +91 81001 08283 or send us an email at enquiry@alcirclebiz.com

Why this matters on AL Biz

On AL Biz, aluminium products are listed across sheets, coils, extrusions, castings, and aluminium scrap.

Clear temper information helps buyers compare offers properly, and sellers avoid disputes.

If you’re listing aluminium products, always include:

• Alloy
• Temper
• Form (sheet, extrusion, billet, etc.)
• Intended application, if possible

Final Takeaway

In aluminium extrusion and flat-rolled products, temper choice depends on what the part needs to do. O temper works best when forming is critical. T temper is used when strength and consistency matter. H temper increases hardness in non-heat-treatable aluminium alloys. That’s why different tempers show up across architecture, automotive, transport, and general manufacturing.

On AL Biz, the global aluminium B2B marketplace, sellers list aluminium products with clear alloy and temper details. This helps buyers compare offers properly and avoid costly mistakes.

If you need help matching aluminium alloys to the right tempers for your listings on AL Biz, do it properly. That’s how serious buyers and sellers operate.