Before starting a project or manufacturing process, we should choose the best material to ensure success. If there are only subtle differences between two aluminum alloys, how to make the decision? Understand the classification, types, series, names, compositions, basic properties and characteristics of most aluminum grades and alloys, as well as temper designation, you are able to select amazing options fast. 

All Aluminum Grades and Alloys - What Type of Aluminum Should Use

Aluminum is the most abundant metal on the earth, comes in silvery-white, soft, non-magnetic, ductile and cost-effective. Let's take an overview of all aluminum alloys and series with their unique features and how they classified.

1.The classification of aluminum

Aluminum alloys can be divided into two categories as the following, but wrought aluminum takes the majority of aluminum products and parts. 

- Cast aluminum alloys: alloying elements >22%, low melting points, and tensile strength.

- Wrought aluminum alloys: alloying elements ≤4%, higher strength, corrosion resistance, conductivity, ductility, etc.

2.The names and types of aluminum

Cast aluminum alloys list and properties

The cast aluminum applied the nomenclature of Aluminum Association, using for numbers, with a decimal between the third and fourth digit. The first number starts from 1 to 9, the middle two numbers indicate the minimum percentage of aluminum and the last digit takes a value of 0 or 1, reveals casting and ingot respectively. The main classes of cast alloys differ in the main elements contained below.

- 1xx.x series: contains minimum 99% aluminum, non-heat-treatable

- 2xx.x series: copper is the main alloying element, heat-treatable

- 3xx.x series: silicon, added copper and/or magnesium, heat-treatable

- 4xx.x series: silicon, heat-treatable

- 5xx.x series: magnesium, non-heat-treatable

- 6xx.x series: unused

- 7xx.x series: zinc, heat-treatable

- 8xx.x series: tin, heat-treatable

- 9xx.x series: other elements

Wrought aluminum alloys list and properties

The most widely used naming scheme of wrought alloys is from International Alloy Designation System, each type of aluminum is given a four-digit number, the first digit presents the dominant alloying element, the second digit (not 0) indicates the variation of the alloy, the last two digits refer to the specific alloy. 

- 1xxx series: essentially pure aluminum with a minimum 99% aluminum content, non-heat treatable, the ultimate tensile strength of 10 to 27 ksi, exceptional corrosion resistance and workability, can be hardened or increase strength through mechanical deformation

Typical 1xxx alloy: 

1100 aluminum (soft, ductile, excellent workability, corrosion resistant, suitable for chemical and food processing, hard-forming applications);

1050 aluminum (popular aluminum sheet grade, low strength compare to other commercial aluminum, most common in H14 temper, used by sheet metal workers)

- 2xxx series: mainly contains copper, added small amounts of magnesium, heat treatable,  ultimate tensile strength of 27 to 62 ksi. It has exceptional strength after heat-treated, prone to corrosion.

Typical 2xxx alloy: 

2024 aluminum (high strength, excellent strength-to-weight ratio, fatigue resistance, high finish, low corrosion resistance, often applied anodized finish);

2011 aluminum (high strength, often used in round bars);

2014 aluminum (high strength, excellent machinability, supplied in aluminum bar and plate, can be interchanged with grade 2011)

- 3xxx series: primarily uses manganese, non-heat treatable, ultimate tensile strength of 16 to 41 ksi, can be work-hardened, moderate strength, great finishing features.

Typical 3xxx alloy:

3003 aluminum (general-purpose, excellent corrosion resistance and workability, can be spun, welded, or brazed)

- 4xxx series: alloyed with silicon, also known as silumin, heat treatable and non-heat treatable, ultimate tensile strength of 25 to 55 ksi, relative low melting points, commonly used as welding wire and brazing alloy.

Typical 4xxx alloy:

4047 aluminum ( good thermal and electrical conductivity, corrosion resistance, a higher melting point)

- 5xxx series: alloyed with magnesium, non-heat treatable, ultimate tensile strength of 18 to 51 ksi, superb corrosion resistance, strain hardenable, weldable, ideal used in marine applications.

Typical 5xxx alloy:

5083 aluminum (highest strength of not heat-treated alloys);

5052 aluminum (resistant to fatigue, corrosion resistance of saltwater and excellent workability, easy to draw or form)

- 6xxx series: alloyed with magnesium and silicon, heat-treatable, ultimate tensile strength of 18 to 58 ksi, not as strong as 2xxx and 7xxx alloys, good formability, weldability, and machinability, mainly used for marine, architectural and general purpose industries.

Typical 6xxx alloy:

6061 aluminum (one of the most widely used alloys, general purpose and versatile heat-treatable alloy, medium strength, good toughness, excellent workability in the annealed condition and excellent corrosion resistance to atmospheric conditions, good finishing characteristics, suitable for anodizing);

6063 aluminum (common extruded aluminum, medium strength, often available in 6063-T6)

- 7xxx series: alloyed with zinc, heat-treatable, ultimate tensile strength of 32 to 88 ksi, the strongest of all wrought alloys, decreased workability and machinability)

Typical 7xxx alloy:

7075 aluminum (outstanding strength, excellent weight-to-strength ratio, can be formed, welded and heat-treated, suitable for aircraft, mobile and highly stressed parts)

- 8xxx series: alloyed with other elements, serve for specific requirements.

Aluminum Alloy Designations

The temper designation follows the cast alloy and wrought alloy with a dash, a letter, and one to three digits.

1. -F: As fabricated

2. -H: Strain hardened (cold worked) 

-H1: Strain hardened only

-H2: Strain hardened and partially annealed

-H3: Strain hardened and stabilized by low-temperature heating

Second digit 

A second digit denotes the degree of hardness

-HX2 = 1/4 hard

-HX4 = 1/2 hard

-HX6 = 3/4 hard

-HX8 = full hard

-HX9 = extra hard

3. -O: Full soft (annealed)

4. -T: Thermally Treated designation

-T1: Cooled from hot working and naturally aged (at room temperature)

-T2: Cooled from hot working, cold-worked, and naturally aged

-T3: Solution heat treated and cold worked

-T4: Solution heat treated and naturally aged

-T5: Cooled from hot working and artificially aged (at elevated temperature)

-T51: Stress relieved by stretching

-T510: No further straightening after stretching

-T511: Minor straightening after stretching

-T52: Stress relieved by thermal treatment

-T6: Solution heat treated and artificially aged

-T7: Solution heat treated and stabilized

-T8: Solution heat treated, cold worked, and artificially aged

-T9: Solution heat treated, artificially aged, and cold worked

-T10: Cooled from hot working, cold-worked, and artificially aged

5. -W: Solution heat treated only

There are also some named aluminum alloys based on the alloying element like Magnox and applications like aerospace alloys. Each aluminum grade has unique characteristics and most suited applications. The selection of material should be from the properties.