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Aluminum Alloys Guide

Alloy: is simply a mixture of metals melted together to form a new metal with characteristics distinct from those metals from which it is made.

Aluminum alloy: is an alloy primarily of pure aluminum, mixed with different alloying elements that give rise to an entire range of materials, each of which is designed to maximize a particular characteristic such as strength, ductility, formability, machine-ability, or electrical conductivity.

Subdivisions of T Temper – Thermally Treated

Letter

Meaning

T1

Naturally aged after cooling from an elevated temperature shaping process, such as extruding.

T2

Cold worked after cooling from an elevated temperature shaping process and then naturally aged.

T3

Solution heat treated, cold worked and naturally aged.

T4

Solution heat treated and naturally aged.

T5

Artificially aged after cooling from an elevated temperature shaping process

T6

Solution heat treated and artificially aged

T7

Solution heat treated and stabilized (overaged).

T8

Solution heat treated, cold worked and artificially aged.

T9

Solution heat treated, artificially aged and cold worked.

T10

Cold worked after cooling from an elevated temperature shaping process and then artificially aged.

 

Additional digits indicate stress relief.

Examples:

TX51 or TXX51 – Stress relieved by stretching.

TX52 or TXX52 – Stress relieved by compressing.

 

 

CAST ALUMINUM ALLOY DESIGNATION SYSTEM

Alloy Series

Principal Alloying Element

1xx.x

99.000% minimum Aluminum

2xx.x

Copper

3xx.x

Silicon Plus Copper and/or Magnesium

4xx.x

Silicon

5xx.x

Magnesium

6xx.x

Unused Series

7xx.x

Zinc

8xx.x

Tin

9xx.x

Other Elements

 

Aluminum Alloys And Their Characteristics

If we consider the seven series of wrought aluminum alloys, we will appreciate their differences and understand their applications and characteristics.

1xxx Series Alloys – (non-heat treatable – with ultimate tensile strength of 10 to 27 ksi) this series is often referred to as the pure aluminum series because it is required to have 99.0% minimum aluminum. They are weldable. However, because of their narrow melting range, they require certain considerations in order to produce acceptable welding procedures. When considered for fabrication, these alloys are selected primarily for their superior corrosion resistance such as in specialized chemical tanks and piping, or for their excellent electrical conductivity as in bus bar applications. These alloys have relatively poor mechanical properties and would seldom be considered for general structural applications. These base alloys are often welded with matching filler material or with 4xxx filler alloys dependent on application and performance requirements.

2xxx Series Alloys – (heat treatable– with ultimate tensile strength of 27 to 62 ksi) these are aluminum / copper alloys (copper additions ranging from 0.7 to 6.8%), and are high strength, high performance alloys that are often used for aerospace and aircraft applications. They have excellent strength over a wide range of temperature. Some of these alloys are considered non-weldable by the arc welding processes because of their susceptibility to hot cracking and stress corrosion cracking; however, others are arc welded very successfully with the correct welding procedures. These base materials are often welded with high strength 2xxx series filler alloys designed to match their performance, but can sometimes be welded with the 4xxx series fillers containing silicon or silicon and copper, dependent on the application and service requirements.

3xxx Series Alloys – (non-heat treatable – with ultimate tensile strength of 16 to 41 ksi) These are the aluminum / manganese alloys (manganese additions ranging from 0.05 to 1.8%) and are of moderate strength, have good corrosion resistance, good formability and are suited for use at elevated temperatures. One of their first uses was pots and pans, and they are the major component today for heat exchangers in vehicles and power plants. Their moderate strength, however, often precludes their consideration for structural applications. These base alloys are welded with 1xxx, 4xxx and 5xxx series filler alloys, dependent on their specific chemistry and particular application and service requirements.

4xxx Series Alloys – (heat treatable and non-heat treatable – with ultimate tensile strength of 25 to 55 ksi) These are the aluminum / silicon alloys (silicon additions ranging from 0.6 to 21.5%) and are the only series which contain both heat treatable and non-heat treatable alloys. Silicon, when added to aluminum, reduces its melting point and improves its fluidity when molten. These characteristics are desirable for filler materials used for both fusion welding and brazing. Consequently, this series of alloys is predominantly found as filler material. Silicon, independently in aluminum, is non-heat treatable; however, a number of these silicon alloys have been designed to have additions of magnesium or copper, which provides them with the ability to respond favorably to solution heat treatment. Typically, these heat treatable filler alloys are used only when a welded component is to be subjected to post weld thermal treatments.

5xxx Series Alloys – (non-heat treatable – with ultimate tensile strength of 18 to 51 ksi) These are the aluminum / magnesium alloys (magnesium additions ranging from 0.2 to 6.2%) and have the highest strength of the non-heat treatable alloys. In addition, this alloy series is readily weldable, and for these reasons they are used for a wide variety of applications such as shipbuilding, transportation, pressure vessels, bridges and buildings. The magnesium base alloys are often welded with filler alloys, which are selected after consideration of the magnesium content of the base material, and the application and service conditions of the welded component. Alloys in this series with more than 3.0% magnesium are not recommended for elevated temperature service above 150 deg F because of their potential for sensitization and subsequent susceptibility to stress corrosion cracking. Base alloys with less than approximately 2.5% magnesium are often welded successfully with the 5xxx or 4xxx series filler alloys. The base alloy 5052 is generally recognized as the maximum magnesium content base alloy that can be welded with a 4xxx series filler alloy. Because of problems associated with eutectic melting and associated poor as-welded mechanical properties, it is not recommended to weld material in this alloy series, which contain higher amounts of magnesium with the 4xxx series fillers. The higher magnesium base materials are only welded with 5xxx filler alloys, which generally match the base alloy composition.

6XXX Series Alloys – (heat treatable – with ultimate tensile strength of 18 to 58 ksi) These are the aluminum / magnesium - silicon alloys (magnesium and silicon additions of around 1.0%) and are found widely throughout the welding fabrication industry, used predominantly in the form of extrusions, and incorporated in many structural components. The addition of magnesium and silicon to aluminum produces a compound of magnesium-silicide, which provides this material its ability to become solution heat treated for improved strength. These alloys are naturally solidification crack sensitive, and for this reason, they should not be arc welded autogenously (without filler material). The addition of adequate amounts of filler material during the arc welding process is essential in order to provide dilution of the base material, thereby preventing the hot cracking problem. They are welded with both 4xxx and 5xxx filler materials, dependent on the application and service requirements.

7XXX Series Alloys – (heat treatable – with ultimate tensile strength of 32 to 88 ksi) These are the aluminum / zinc alloys (zinc additions ranging from 0.8 to 12.0%) and comprise some of the highest strength aluminum alloys. These alloys are often used in high performance applications such as aircraft, aerospace, and competitive sporting equipment. Like the 2xxx series of alloys, this series incorporates alloys which are considered unsuitable candidates for arc welding, and others, which are often arc welded successfully. The commonly welded alloys in this series, such as 7005, are predominantly welded with the 5xxx series filler alloys.

 

Buymetal.com Alloys

Alloy 2124
This alloy exhibits good strength retention and creep resistance at elevated temperatures up to 350° F (177°C). With high strength and good machinability and has excellent exfoliation corrosion resistance.

2124-T851: short-transverse ductility and fracture toughness guarantees

Alloy 2024
Heat treatable with high strength, good machinability and fair corrosion resistance. It welds very poorly.

2024-O: Annealed (or "soft", bendable condition)
2024-T3: Heat treated, cold worked and naturally aged
2024-T351: Heat treated, cold worked and naturally aged
2024-T851: good strength retention and creep resistance at elevated temperatures up to 350 degrees. short-transverse ductility, high strength and good machinability and has excellent exfoliation corrosion resistance.

Alloy 3003
This alloy is not heat treatable but welds very well and has very good workability. Like alloy 1100 it is somewhat soft and difficult to machine.

3003-H14: Strain hardened
3003-H22: Strain hardened, partially annealed

Alloy 5083
Alloy 5083 also retains exceptional strength after welding. It has the highest strength of the non-heat treatable alloys but is not recommended for use in temperatures in excess of 65°C.

5083-H116: high strength welded applications, with excellent marine environment corrosion resistance.
5083-H321: Work hardened by rolling then stabilized by low-temperature heat treatment to quarter hard

Alloy 5052
Strong, not heat treatable, easily welded, with excellent corrosion characteristics.

5052-H32: Strain-hardened and stabilized


Alloy 5086
Very strong, not heat treatable, with excellent corrosion resistance and good weldability.

5086-H116: Strain-hardened only
5086-H32: Strain-hardened and stabilized
5086-H34: Strain-hardened and stabilized

Alloy 6061
Heat treatable, easily welded, with very good corrosion resistance and finishing characteristics. Very commonly used for architectural products

6061-O: Annealed (or "soft", bendable condition)
6061-T4: Heat treated and naturally aged
6061-T6: Heat treated and artificially aged
6061-T65: Heat treated and artificially aged
6061-T6511: Heat treated and artificially aged
Structural - Aluminum Association: extruded product with inside radius corners used for structural applications and fabrication where greater strength, lightweight and corrosion resistance are important.
Tapered Legs - American Standard: extruded product with inside radius corners used for structural applications and fabrication where greater strength, lightweight and corrosion resistance are important.

Alloy 6063
This heat treatable is specifically designed for extrusions, very popular for architectural shapes.

6063-T52: Cooled from an elevated temperature shaping process and artificially aged

Alloy 7050
High strength, excellent corrosion resistance, heat treatable, and weldable, but has poor workability.

7050-T7451: Heat treated, overaged and strengthened

Alloy 7075
Heat treatable, this alloy is the strongest and hardest aluminum alloy. It has good machining characteristics but is not very easliy welded nor is it very workable.

7075-7351: very high strength, good stress-corrosion cracking resistance, used for highly stressed structural parts. Applications include aircraft fittings, gears and shafts, fuse parts, meter shafts and gears, missile parts, regulating valve parts, worm gears, keys, and various other commercial aircraft, aerospace and defense equipment.

7075-73511: Solution heat treatment and specially artificially aged. Applies to 7075 alloy extrusions which have been specially aged to make the material resistant to stress-corrosion
7075-T6: Heat treated and artificially aged
7075-T651: Heat treated and artificially aged

Cast Tool & Jig

high-quality, accurately machined aluminum plate which received a thermal stress relieving treatment to provide dimensional stability when machining. Typically, it can be heated repeatedly to temperatures as high as 800°F (427°C, when cooled it will return to its basic dimension with a minimum of distortion, depending upon the extent of machining.

K100S: Dimensionally stable aluminum plate with vacuum integrity combined with improved mechanical properties, excellent corrosion resistance and Micro-Sheen finish.
MIC-6: cast to near net thickness with a stress-relieved, granular structure to virtually eliminate distortion from machining and end use temperature fluctuations.

 

DISCLAIMER
This Data is indicative only and must not be seen as a substitute for the full specification from which it is drawn. In particular, the mechanical property requirements vary widely with temper, product and product dimensions. The information is based on our present knowledge and is given in good faith. However, no liability will be accepted by the Company is respect of any action taken by any third party in reliance thereon. As the products detailed may be used for a wide variety of purposes and as the Company has no control over their use; the Company specifically excludes all conditions or warranties expressed or implied by statute or otherwise as to dimensions, properties and/or fitness for any particular purpose.