Table of Contents
- Introduction
- Overview of Aluminum Alloy Temper Designations
- Applications and Variations of the O Temper
- Applications and Variations of the F Temper
- Applications and Variations of the W Temper
- Applications and Variations of the H Tempers
- Applications and Variations of the T Tempers
- Understanding the Second and Third Digits in Temper Designations
- Detailed Tables of Temper Designations and Their Applications
- Comparison Table of Aluminum Alloys with Different Tempers
- Summary
- References
Introduction
Aluminum alloys are used extensively across various industries due to their exceptional properties such as high strength-to-weight ratio, corrosion resistance, and ease of fabrication. The performance of aluminum alloys can be significantly altered through different tempering processes. The temper designation of an aluminum alloy provides essential information about the mechanical and physical properties of the material. This article aims to decode the temper designations for aluminum alloys, focusing on the applications and variations of the O, F, W, H, and T tempers. By understanding these designations, engineers and materials scientists can select the most appropriate aluminum alloy for their specific applications.
Overview of Aluminum Alloy Temper Designations
The temper designation system for aluminum alloys is standardized by the Aluminum Association and provides a systematic method for identifying the mechanical treatment of an alloy. The designations consist of a letter followed by one or more digits. The primary temper designations are:
- F (As Fabricated): No special control over thermal or strain-hardening conditions.
- O (Annealed): Annealed to obtain the lowest strength temper.
- H (Strain Hardened): Strengthened by cold working, with additional digits indicating specific treatments.
- W (Solution Heat Treated): Unstable temper applicable only to alloys that age spontaneously at room temperature after solution heat treatment.
- T (Thermally Treated): Indicates thermally treated to produce stable tempers other than F, O, or H, with additional digits indicating specific sequences.
Each of these designations includes variations that provide more specific information about the material’s processing history and properties.
Applications and Variations of the O Temper
Applications
The O temper, or annealed condition, is used for applications requiring maximum ductility and minimum strength. Typical applications include:
- Sheet metal forming: Due to its excellent ductility, O temper aluminum is ideal for complex shapes.
- Deep drawing: Used in the production of intricate parts such as kitchen utensils and automotive components.
- Stamping and spinning: Employed in creating parts requiring extensive shaping without cracking.
Variations
There are no significant variations within the O temper designation as it specifically refers to the fully annealed state of the alloy.
Applications and Variations of the F Temper
Applications
The F temper, or as-fabricated condition, is used when no special control over thermal or strain-hardening conditions is required. Applications include:
- Raw stock for machining: Used as starting material for components that will be further processed.
- Forgings and extrusions: Often employed in aerospace and automotive industries where further processing is anticipated.
Variations
Similar to the O temper, the F temper does not have significant variations as it refers to the as-fabricated state of the alloy.
Applications and Variations of the W Temper
Applications
The W temper, or solution heat-treated condition, is used for applications requiring maximum formability immediately after heat treatment. Typical applications include:
- Aircraft structures: Where immediate forming and later aging are beneficial.
- Heat exchangers: Utilizing the W temper’s unique properties before the material naturally ages.
Variations
- W51: Solution heat-treated and then artificially aged for a short period to reach a specific state.
- W71: Solution heat-treated and aged at room temperature for a longer duration before use.
Applications and Variations of the H Tempers
Applications
The H temper designations are used for strain-hardened alloys. Applications vary widely based on the specific H temper:
- H12 (1/4 Hard): Used in applications requiring moderate strength and formability, such as automotive panels.
- H14 (1/2 Hard): Employed in structural components requiring a balance of strength and formability.
- H18 (Full Hard): Ideal for applications requiring maximum strength, such as aerospace components and pressure vessels.
Variations
- H1X: Strain-hardened only.
- H2X: Strain-hardened and partially annealed.
- H3X: Strain-hardened and stabilized.
- H4X: Strain-hardened and lacquered or painted.
The second digit indicates the degree of strain-hardening, ranging from 1 (1/8 hard) to 8 (full hard).
Detailed Table of H Temper Variations
| Temper Designation | Description | Applications |
|---|---|---|
| H11 | 1/8 Hard, strain-hardened | Moderate formability with some strength |
| H12 | 1/4 Hard, strain-hardened | Automotive panels, moderate strength |
| H13 | 3/8 Hard, strain-hardened | Higher strength than H12 with some formability |
| H14 | 1/2 Hard, strain-hardened | Structural components, balance of strength and formability |
| H16 | 3/4 Hard, strain-hardened | Higher strength applications |
| H18 | Full Hard, strain-hardened | Aerospace components, pressure vessels |
| H19 | Strain-hardened to exceed standard hardening limits | Maximum strength applications requiring ultimate hardness |
| H22 | 1/4 Hard, strain-hardened and partially annealed | Moderate strength applications |
| H24 | 1/2 Hard, strain-hardened and partially annealed | Balance of strength and formability |
| H26 | 3/4 Hard, strain-hardened and partially annealed | Higher strength applications |
| H28 | Full Hard, strain-hardened and partially annealed | High-strength applications |
| H32 | 1/4 Hard, strain-hardened and stabilized | Stabilized for thermal stability |
| H34 | 1/2 Hard, strain-hardened and stabilized | Structural components with thermal stability |
| H36 | 3/4 Hard, strain-hardened and stabilized | High-strength components with stability |
| H38 | Full Hard, strain-hardened and stabilized | Maximum strength with thermal stability |
| H39 | Strain-hardened to exceed standard hardening limits and stabilized | Ultimate strength with thermal stability |
| H42 | 1/4 Hard, strain-hardened and lacquered/painted | Decorative applications |
| H44 | 1/2 Hard, strain-hardened and lacquered/painted | Decorative and functional applications |
| H46 | 3/4 Hard, strain-hardened and lacquered/painted | High-strength decorative applications |
| H48 | Full Hard, strain-hardened and lacquered/painted | Maximum strength with decorative finish |
Applications and Variations of the T Tempers
Applications
The T temper designations apply to thermally treated alloys to achieve stable conditions other than F, O, or H. Applications include:
- T3 (Solution heat-treated and cold worked): Used in aircraft skins and structural components.
- T4 (Solution heat-treated and naturally aged): Employed in automotive body panels and aerospace structures.
- T6 (Solution heat-treated and artificially aged): Ideal for high-strength applications such as heavy-duty structural components and machinery parts.
Variations
- T1: Cooled from an elevated temperature shaping process and naturally aged.
- T5: Cooled from an elevated temperature shaping process and artificially aged.
- T7: Solution heat-treated and overaged/stabilized.
- T9: Solution heat-treated, artificially aged, and cold worked.
Detailed Table of T Temper Variations
| Temper Designation | Description | Applications |
|---|---|---|
| T1 | Cooled from an elevated temperature shaping process and naturally aged | Structural shapes, profiles, and extrusions |
| T2 | Cooled from an elevated temperature shaping process, cold worked, and naturally aged | Products requiring additional cold working |
| T3 | Solution heat-treated and cold worked | Aircraft skins, structural components |
| T4 | Solution heat-treated and naturally aged | Automotive body panels, aerospace structures |
| T5 | Cooled from an elevated temperature shaping process and artificially aged | General structural applications |
| T6 | Solution heat-treated and artificially aged | High-strength structural components, machinery parts |
| T7 | Solution heat-treated and overaged/stabilized | Applications requiring dimensional stability |
| T8 | Solution heat-treated, cold worked, and artificially aged | High-strength, high-precision applications |
| T9 | Solution heat-treated, artificially aged, and cold worked | High-strength and high-precision components |
| T10 | Cooled from an elevated temperature shaping process, cold worked, and artificially aged | Complex structural applications requiring high strength |
Understanding the Second and Third Digits in Temper Designations
Second Digit
If a second digit follows the first, it describes the aluminum alloy’s remaining capacity to be further strain-hardened. The number represents an approximate percentage between the “O” temper (re-softened aluminum via annealing) and the accepted strain-hardening limit (i.e., “8”).
- 2: 25% of the accepted limit
- 4: 50% of the accepted limit
- 6: 75% of the accepted limit
- 8: Maximum strain hardening
- 9: Exceeds accepted limits
Third Digit
A third digit represents some special variation to the normal process associated with the first two digits. This digit is less commonly used but indicates modifications or further refinement to the standard temper designation.
Detailed Tables of Temper Designations and Their Applications
Table of Aluminum Alloys with O Temper
| Alloy | O Temper (Annealed) Applications |
|---|---|
| 1100 | Deep drawing, spun hollowware |
| 3003 | Chemical equipment, cooking utensils |
| 5052 | Marine hardware, pressure vessels |
| 6061 | Complex extrusions, automotive parts |
| 7075 | Aerospace applications, structural components |
Table of Aluminum Alloys with F Temper
| Alloy | F Temper (As Fabricated) Applications |
|---|---|
| 1100 | Raw stock for machining, non-critical applications |
| 3003 | Architectural applications, electrical components |
| 5052 | Automotive parts, pressure vessels |
| 6061 | Extrusions, forgings |
| 7075 | Aircraft structures, military applications |
Table of Aluminum Alloys with W Temper
| Alloy | W Temper (Solution Heat Treated) Applications |
|---|---|
| 2024 | Aircraft structures, automotive components |
| 6061 | Structural applications, heat exchangers |
| 7075 | High-stress components, aerospace fittings |
Table of Aluminum Alloys with H Tempers
| Alloy | H Temper Variations | Applications |
|---|---|---|
| 1100 | H12, H14, H18 | Packaging, heat exchangers |
| 3003 | H12, H14, H18 | Automotive panels, roofing |
| 5052 | H32, H34, H36 | Marine applications, pressure vessels |
| 6061 | H12, H14, H18 | Structural components, machinery parts |
| 7075 | H32, H34, H36 | Aerospace components, high-stress parts |
Table of Aluminum Alloys with T Tempers
| Alloy | T Temper Variations | Applications |
|---|---|---|
| 2024 | T3, T4, T6 | Aircraft skins, structural components |
| 6061 | T5, T6, T651 | General structural applications, machinery parts |
| 7075 | T6, T651, T73 | Aerospace components, high-strength applications |
Comparison Table of Aluminum Alloys with Different Tempers
| Alloy | Temper | Description | Applications |
|---|---|---|---|
| 1100 | O | Fully annealed | Deep drawing, spun hollowware |
| 1100 | H14 | 1/2 Hard, strain-hardened | Packaging, heat exchangers |
| 3003 | O | Fully annealed | Chemical equipment, cooking utensils |
| 3003 | H14 | 1/2 Hard, strain-hardened | Automotive panels, roofing |
| 5052 | O | Fully annealed | Marine hardware, pressure vessels |
| 5052 | H34 | 1/2 Hard, strain-hardened and stabilized | Marine applications, pressure vessels |
| 6061 | O | Fully annealed | Complex extrusions, automotive parts |
| 6061 | T6 | Solution heat-treated and artificially aged | High-strength structural components, machinery parts |
| 7075 | O | Fully annealed | Aerospace applications, structural components |
| 7075 | T651 | Solution heat-treated, stress-relieved by stretching, and artificially aged | Aerospace components, high-stress applications |
Summary
Understanding the temper designations of aluminum alloys is crucial for selecting the right material for specific applications. The temper designations provide detailed information about the mechanical treatment and resultant properties of the alloy. By understanding these designations, engineers and material scientists can optimize the performance and longevity of their products.
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