Different Types of Aluminium Alloys
by AMC
Posted on September 11, 2025 at 05:01 PM
Aluminium is the second most utilized metal due to its high strength to weight ratio, durability, and light weight. Pure Aluminium can be quite soft and few structural applications exist for pure Aluminium; as such, engineers typically alloy small amounts of other elements to produce aluminium with properties fit for structural applications. Alloying increases strength, formability, and corrosion resistance, while still maintaining aluminium’s low density and good electrical and thermal conductivities.
In this blog, we’ll explore the different types of aluminium alloys, how they are categorized, and the unique aluminium alloy composition and properties that make them ideal for various applications. We’ll also cover how to choose the right material for your needs by comparing aluminium alloys types, discussing the aluminium grades, and reviewing key series in the aluminium alloys series classification system.
What are Aluminium Alloys?
An aluminium alloy is a metallic mixture of aluminium along with one or more alloying combinations such as copper, magnesium, silicon, manganese or zinc. Alloying is beneficial to improve the aluminium alloys properties such as mechanical strength, hardness, and corrosion resistance of the base metal, while still maintaining its low weight and also its good conductivity.
The Two Main Types of Aluminium Alloys
Aluminium alloys fall into two main categories based on how they are produced.
Wrought Aluminium Alloys
Wrought aluminium alloys are shaped from solid billets by rolling, extrusion, or forging. Their uniform structure gives better ductility and fatigue strength, making them suitable for sheets, plates, bars, tubes, and structural components. They are designated by four-digit numbers (e.g., 6061, 2024, 7075) and include both heat-treatable and non-heat-treatable grades.
Cast Aluminium Alloys
Cast aluminium alloys are made by pouring molten aluminium into moulds, allowing complex shapes for engine blocks, pump housings, and machinery parts. They use four-digit numbers with a decimal point (e.g., 356.0), where the first digit indicates the major alloying element. Cast products generally have lower ductility but are excellent for mass production and intricate designs.
Wrought Aluminium Alloy Series (1xxx–7xxx)
The AA classification system for wrought aluminium divides alloys into series based on their principal alloying element. Each series has characteristic properties and common applications. The first digit of the four‑digit designation identifies the series. The summary below outlines the main alloying elements and typical uses for each series.
| Series | Main alloying element(s) | Key properties & common uses |
|---|---|---|
| 1xxx | ≥99 % aluminium | High electrical/thermal conductivity and excellent corrosion resistance; used in electrical conductors, foil and chemical processing equipment. |
| 2xxx | Copper | High strength but lower corrosion resistance; heat‑treatable; used in aircraft fuselages, truck wheels and high‑stress components. |
| 3xxx | Manganese | Moderate strength with good workability; non‑heat‑treatable; common in beverage cans, cooking utensils and general sheet work. |
| 4xxx | Silicon | Low melting point and good wear resistance; used for welding wire, brazing alloys, architectural facades and forged engine pistons. |
| 5xxx | Magnesium | Moderate‑to‑high strength with excellent corrosion resistance and good weldability; ideal for marine components, appliances and automotive parts. |
| 6xxx | Magnesium & silicon | Medium strength, good formability and weldability; heat‑treatable; widely used in structural extrusions, architectural profiles, trucks and recreational equipment. |
| 7xxx | Zinc | Moderate‑to‑very high strength; heat‑treatable; employed in airframe structures, high‑stress parts and sporting equipment. |
Cast Aluminium Alloy Series (1xx.x–8xx.x)
Cast alloys follow a similar classification scheme; however, the composition range is broader and the numbering uses a decimal point to distinguish castings from ingots. The series from 1xx.x to 8xx.x represent increasing alloying content, and the main characteristics are outlined below.
Understanding these series helps designers select the right cast alloy for properties such as fluidity, strength, machinability and corrosion resistance.
| Series | Main alloying element(s) | Key properties & typical applications |
|---|---|---|
| 1xx.x | ≥99 % aluminium | Very high conductivity and excellent corrosion resistance; used in electrical rotors and thermal conductors. |
| 2xx.x | Copper with magnesium | High strength but lower corrosion resistance; used in cylinder heads, pistons, housings and bearings. |
| 3xx.x | Silicon with copper and/or magnesium | High strength and wear resistance with good corrosion resistance; used in motor parts, structural parts, marine and aircraft castings. |
| 4xx.x | Silicon | Moderate strength, high ductility and good impact resistance; suitable for bridge railings, dental equipment and cookware. |
| 5xx.x | Magnesium | Moderate‑to‑high strength with high corrosion resistance and good machinability; common in architectural and ornamental castings and welded assemblie. |
| 7xx.x | Zinc | Good finish, corrosion resistance and high strength through heat treatment; used in automotive parts, mining equipment and brazing castings. |
| 8xx.x | Tin | Low friction; mainly used for bearing and bushing applications. |
Aluminium Alloy Composition
The performance of an aluminium alloy depends on which elements are added and in what quantities. Each alloying element influences the mechanical and chemical behaviour of the alloy. Below is an overview of how the primary alloying elements affect aluminium:
| Alloying Element | Key Effects on Aluminium | Typical Applications |
|---|---|---|
| Copper (Cu) | Increases strength, enables precipitation hardening, but lowers ductility and corrosion resistance. | Aerospace, defence, and high-strength structural parts. |
| Manganese (Mn) | Improves solution strengthening, enhances strain hardening, retains ductility and corrosion resistance. | Cooking utensils, heat exchangers, roofing sheets. |
| Silicon (Si) | Reduces melting temperature, improves fluidity and wear resistance; with magnesium forms heat-treatable alloys. | Welding wires, brazing alloys, automotive engine parts. |
| Magnesium (Mg) | Boosts strength through solid-solution hardening, enhances strain hardening. | Shipbuilding, trucks, pressure vessels. |
| Magnesium + Silicon (Mg₂Si) | Forms magnesium-silicide, making alloys heat-treatable and easy to extrude. | Handrails, automotive frames, bicycle frames, structural profiles. |
| Zinc (Zn) | With Mg and Cu, produces highest-strength heat-treatable alloys. | Aerospace, armoured vehicles, sporting equipment. |
| Other elements (Fe, Cr, Ni, Ti, Zr) | Refine grain structure, enhance high-temperature strength, improve machinability. | Specialized industrial and machining alloys. |
| Lead (Pb) & Bismuth (Bi) | Improve machinability but reduce weldability. | Free-machining aluminium products. |
Example compositions of popular wrought alloys
The table below lists typical compositions for several widely used wrought aluminium grades. These values are representative; actual specifications may vary slightly by supplier. The compositions illustrate how varying alloying elements tailor properties for specific applications
| Alloy | Cu (%) | Mg (%) | Si (%) | Zn (%) | Mn (%) | Other notes |
|---|---|---|---|---|---|---|
| 2024 | 4.9 | 1.8 | 0.5 | 0.25 | 0.9 | High strength and good fatigue resistance; low corrosion resistance. |
| 5083 | 0.1 | 4.9 | 0.4 | 0.25 | 1.0 | Exceptional corrosion resistance in seawater; highest strength among non‑heat‑treated grades. |
| 6061 | 0.4 | 1.2 | 0.8 | 0.25 | 0.15 | Common “structural” alloy with good corrosion resistance and weldability. |
| 7050 | 2.6 | 2.6 | 0.12 | 6.7 | 0.10 | High strength, fatigue resistance and stress‑corrosion resistance; used for thick plates and aerospace components. |
| 7075 | 2.3 | 2.5 | — | 6.2 | — | One of the strongest wrought alloys; good fatigue strength but lower corrosion resistance due to copper. |
Properties of Aluminium Alloys
Aluminium alloys share certain desirable characteristics, low density, good conductivity and non‑magnetic behaviour, yet their mechanical and corrosion properties vary widely depending on composition and processing. The following table summarises key property trends across the wrought series, helping designers quickly assess the trade‑offs between strength, workability, corrosion resistance and weldability. Remember that within each series there are many specific alloys whose exact properties depend on temper and processing. The aluminium alloys properties vary by series:
| Series | Mechanical & physical properties | Corrosion and weldability |
|---|---|---|
| 1xxx | Very soft, high ductility and excellent electrical/thermal conductivity | Outstanding corrosion resistance; readily weldable; used when strength is not critical. |
| 2xxx | High strength and good fatigue resistance; heat‑treatable | Lower corrosion resistance; often clad with 6xxx or pure aluminium for protection; welding requires care. |
| 3xxx | Moderate strength, good formability and work hardening ability | Good corrosion resistance and weldability; widely used for cooking utensils and beverage cans. |
| 4xxx | Low melting point and moderate strength | Good wear resistance and excellent fluidity for casting; often used as filler metals; weldability depends on silicon content. |
| 5xxx | Highest strength of non‑heat‑treatable alloys; excellent fatigue properties | Very good corrosion resistance (especially in marine environments) and weldability; used in shipbuilding, pressure vessels and cryogenic tanks. |
| 6xxx | Medium strength with good toughness; heat‑treatable and easily extruded | Good corrosion resistance and weldability; the most versatile series for structural applications. |
| 7xxx | Highest strength among aluminium alloys | Moderate corrosion resistance (may require protective coatings); welding can be challenging due to stress‑corrosion susceptibility; used in aerospace and sporting equipment. |
Heat‑Treatable vs. Non‑Heat‑Treatable Aluminium Alloys
Aluminium alloys can be classified not only by their composition but also by how they gain strength. Some alloys respond to heat treatment, where controlled heating and cooling increase hardness and tensile strength. Others rely on mechanical working processes to improve performance, making it essential to distinguish between heat-treatable and non-heat-treatable grades when selecting materials for critical applications.
| Category | Strengthening Method | Common Grades | Key Characteristics | Typical Applications |
|---|---|---|---|---|
| Heat-Treatable Alloys | Solution heat treatment → quenching → aging | 6061, 7075, 2024 | High strength even in thin gauges; can be precipitation-hardened; more expensive to process | Aerospace structures, defence equipment, high-performance automotive parts |
| Non-Heat-Treatable Alloys | Cold working (strain hardening) | 3003, 5052, 1100-O | Retain properties regardless of heat treatment; easier to form and weld; require thicker sections for same strength | Marine components, roofing, chemical tanks, fuel tanks |
Choosing the Right Aluminium Alloy
Choosing an aluminium alloy means weighing the issues of strength, environment, fabrication mode of action, and price. The guidelines below identify the most common issues with practical examples.
- Strength issues – If ultimate strength and fatigue resistance are of primary importance, then heat-treatable alloys such as 2xxx and 7xxx series are the right choice. Alloys such as 2024 are used very frequently on aircraft fuselages, while 7075 and 7050 are generally the oldest strength prone response to mechanical and aerospace engineering spaceflight.
- Environment issues – The 5xxx series (for example: 5083) alloys have very good corrosion resistance; thus they are more appropriate for applications involving marine, chemical or for cryogenic storage. The 2xxx grades have limited corrosion resistance and should normally have some sort of protective coating (liquids would separate the aluminium from the environmental exposure).
- Weldability and formability – If the product can be made from non-heat-treatable alloys of the 3xxx or 5xxx series, choose those non-heat-treatable alloys. 5052 grade gives a wonderful combination of strong weldability and oxidation or corrosion resistance, 3003 readily forms into duct work, utensils or fuel tanks.
- Cost issues – 1xxx and 3xxx series aluminium alloys have low cost, but have limited strength for their weight category. Normally, the 6xxx series of alloys (6061) has sufficient strength, corrosion resistance, and price regime allow it to be applied to a wide variety of uses, and workflows (e.g., structural, and architectural design).
- Use-case issues – Aerospace engineers will common 2024, 7050, and 7075 grades of aluminium alloys in their support structures for aircraft. Marine and chemical equipment also commonly use 5083, and 5052 as its high oxidisation resistant coatings make them convenient for longevity in terrible environments. Last, construction will typically use the extrusion of 6061, 6063 alley grades whereas packaging will use series of 3xxx alloys including a seamer to make a seamless can; 3004 is the common choice for Lake of Ontario and even many fruit cup manufacturers.
Conclusion and Call to Action
When selecting an aluminium alloy, consider the strength you need, the environment in which you are working, how the material will be fabricated and of course the budget. Heat-treatable 2xxx or 7xxx series alloys are a great choice for applications requiring high strength, while magnesium-rich 5xxx grades are ideal for more corrosive environments. If welding and formability are priorities, then consider non-heat-treatable 3xxx or 5xxx alloys. Amardeep Steel Centre stocks a comprehensive range of aluminium alloys from all major series, offering plenty of material options to meet your project requirements.
Explore our full range of aluminium alloys by type today, download our aluminium alloy series comparison chart, or request a quote based on your project specifications; our technical experts are standing by to assist you in choosing the right aluminium alloy for your application.