Aluminum is not a single material. It is a family of alloys, each engineered for a specific combination of strength, corrosion resistance, formability, machinability, and cost. There are hundreds of registered aluminum alloy designations worldwide, but the vast majority of industrial procurement concentrates on a small number of proven grades across seven main series.

This guide explains how the aluminum alloy designation system works, covers each series from 1xxx through 7xxx in detail, and provides a practical framework for selecting the right alloy for your application. Each section links to detailed comparison articles where you can go deeper on specific alloy pairs.

1. The Aluminum Alloy Designation System

The international aluminum alloy designation system uses a four-digit number to identify wrought aluminum alloys. The first digit identifies the principal alloying element that defines the series. The remaining digits identify the specific alloy within that series or indicate the aluminum purity level.

For example, in the alloy designation 6061: the first digit 6 tells you this is an aluminum-magnesium-silicon alloy. The digits 061 identify the specific composition within the 6xxx family. The designation that follows the alloy number — separated by a hyphen — is the temper code, which describes the heat treatment or cold-working condition: T6 for artificially aged after solution heat treatment, H14 for quarter-hard cold-worked, and so on.

This system is maintained by the Aluminum Association and is recognized globally under standards including ASTM, EN, and ISO. Cast aluminum alloys use a different designation system (A380, A356, etc.) and are outside the scope of this guide, which focuses on wrought flat-rolled products: sheet, plate, and coil.

The seven wrought alloy series at a glance:

The table above is a starting framework. The sections below cover each series in detail, with mechanical properties, temper guidance, application examples, and links to in-depth comparison articles.

2. 1xxx Series: Commercially Pure Aluminum

The 1xxx series alloys contain at least 99.0% aluminum, with the remaining fraction consisting of controlled amounts of iron, silicon, and copper. 1100 is the most widely used grade, containing at least 99.0% aluminum. Higher-purity grades such as 1050 (99.5% Al) and 1070 (99.7% Al) are used in electrical and specialty applications.

Key properties

1xxx aluminum is the softest and most formable wrought aluminum alloy family. Tensile strength in the H14 temper is approximately 124 MPa — well below structural alloys — but formability in the O (annealed) temper is outstanding. The alloys are not heat-treatable; strength is increased only by cold working, captured in the H-series temper codes.

Thermal conductivity is the highest of any common aluminum alloy series at approximately 222 W/m·K for 1100, compared to 163 W/m·K for 3003 and 130 W/m·K for 7075. Electrical conductivity is approximately 59% IACS. Both properties make 1xxx the preferred series for heat transfer and electrical applications.

Applications

• Food-contact packaging: foil, containers, bottle caps — FDA and EU food-contact compliant

• Heat exchanger fins: 36% better thermal conductivity than 3003, directly improving fin efficiency

• Chemical processing tanks: pure aluminum resists organic acids and solvents better than alloyed grades

• Electrical conductors and busbars: highest conductivity in the aluminum alloy family

• Reflective and decorative panels: purer grain structure produces the clearest anodize finish

Common grades and tempers

1100-H14 is the standard specification for general industrial sheet. 1100-O is used for deep drawing and complex forming operations. 1050 and 1060 are specified in markets where higher purity is required for electrical or chemical applications.

→ Compare 1100 vs 3003 aluminum

→ Aluminum sheet vs coil (food packaging section)

3. 2xxx Series: Aluminum-Copper Alloys

The 2xxx series uses copper as the primary alloying element. Copper forms strengthening precipitates (primarily Al2CuMg) during the aging process, raising tensile strength to levels that approach some structural steels. 2024 is the most important grade, with a tensile strength of 483 MPa in the T3 temper.

Key properties

The defining advantage of 2xxx aluminum is its fatigue crack growth resistance. While 7xxx alloys achieve higher static tensile strength, 2024-T3 propagates fatigue cracks more slowly under the same cyclic stress conditions — and its fracture toughness of approximately 36 MPa·m½ is about 33% higher than 7075-T6. These properties are why damage-tolerant aircraft design specifies 2024 for tension-loaded skin panels that experience tens of thousands of pressurization cycles.

The significant trade-off is corrosion resistance. The copper content creates micro-galvanic cells at grain boundaries that accelerate pitting in humid and saline environments. Aircraft-grade 2024 sheet is commonly supplied in Alclad form — with a thin layer of pure aluminum metallurgically bonded to each face as sacrificial corrosion protection.

Fusion welding is not recommended for 2xxx alloys due to hot cracking in the heat-affected zone. Aircraft structures use riveted or bolted joints; modern aerospace manufacturing increasingly uses friction stir welding (FSW), which avoids the liquid-phase issues of fusion welding.

Applications

• Aircraft fuselage lower skin and pressure bulkheads (2024-T3): tension-loaded, fatigue-critical

• Lower wing skin panels: cyclic bending loads, damage-tolerance design

• Fuselage frames and bulkheads (2024-T351): thick plate, precision-machined

• Helicopter rotor fittings and propeller blades: high-cycle rotating fatigue loading

Common grades and tempers

2024-T3 (sheet, cold-worked, naturally aged) is the most widely specified. 2024-T351 (stress-relieved plate) is standard for machined structural components. 2024-T4 is used for forming operations before final aging.

→ Compare 2024 vs 7075 aluminum for aerospace

4. 3xxx Series: Aluminum-Manganese Alloys

The 3xxx series adds manganese (typically 1.0 to 1.5%) to the aluminum base. Manganese dissolves into the aluminum matrix as a solid-solution strengthener, raising tensile strength approximately 20% above the 1xxx series without significantly affecting corrosion resistance, formability, or weldability. 3003 is by far the most widely used grade and is among the highest-volume aluminum alloys produced globally.

Key properties

3003-H14 delivers 152 MPa tensile strength — modest by engineering standards, but sufficient for the vast majority of general fabrication applications. The alloy is not heat-treatable. Corrosion resistance is excellent in atmospheric, freshwater, and petroleum environments. Weldability is outstanding with standard MIG/TIG processes using ER4043 filler wire.

The most important practical difference from 1xxx is the H24 temper, which provides a combination of ductility and strength well-suited to roll-forming operations. 3003-H24 can be corrugated into roofing profiles, drawn into cookware shapes, and formed into HVAC duct sections without cracking — while retaining enough strength for the finished component’s service requirements.

Applications

• Roofing sheet and corrugated cladding (3003-H24): the global standard for aluminum roofing

• HVAC ductwork (3003-H14): formed into duct sections and sealed with Pittsburgh lock seams

• Liquid storage tanks: petroleum products, water, aviation fuel

• Cookware and kitchen equipment: deep-drawn with good surface hardness

• Channel letter coil for signage: continuous bending on letter-bending machines

• General industrial sheet fabrication: the default “commercial-grade” aluminum sheet

Common grades and tempers

3003-H14 for general sheet; 3003-H24 for roofing and forming; 3003-O for deep drawing. 3004 is used for beverage can bodies and shares similar properties with higher Mg content.

5. 4xxx Series: Aluminum-Silicon Alloys

The 4xxx series uses silicon as the primary alloying element. Silicon reduces the melting point and increases fluidity, which is why 4xxx alloys are most commonly used as welding filler wire and brazing alloys rather than as base metal sheet or plate.

Key properties and role

4043 is the most widely used welding filler wire for aluminum. Its silicon content (4.5 to 6.0%) produces a fluid weld pool that fills joints cleanly and resists hot cracking — making it the standard filler for welding 6xxx-series structural alloys and 3xxx-series sheet. When 6061 components are MIG or TIG welded, ER4043 is typically the default filler specification.

4032 is a specialty alloy used for pistons and engine components. Its low coefficient of thermal expansion and good wear resistance at elevated temperatures make it suitable for high-temperature mechanical applications where standard aluminum alloys would soften.

Unlike most other series, 4xxx alloys are rarely purchased as flat-rolled sheet or plate for fabrication. Procurement of 4xxx material is almost always in the form of welding wire spools or brazing sheet with a 4xxx cladding layer.

When 4xxx matters for sheet buyers

If you are welding 6061, 5052, or 3003 sheet and plate, 4043 filler wire is the standard consumable you need to specify alongside your base metal order. Knowing the 4xxx series designation helps you understand why ER4043 is specified and what properties it contributes to the weld joint.

6. 5xxx Series: Aluminum-Magnesium Alloys

The 5xxx series is the corrosion-resistant workhorse of the aluminum alloy family. Magnesium is the primary alloying element, typically ranging from 0.5% (in the lower-strength grades) to 4.9% (in the marine-grade 5083). Higher magnesium content produces both higher strength and better resistance to corrosion in saltwater and marine atmospheres.

Key properties

The defining characteristic of 5xxx alloys is their corrosion resistance. When aluminum is exposed to air, it forms a self-healing aluminum oxide film that blocks further corrosion. Magnesium strengthens and thickens this film, making 5xxx alloys significantly more resistant to pitting and stress-corrosion cracking in chloride environments than 1xxx, 3xxx, or 6xxx alloys.

The alloys are not heat-treatable; strength is achieved through cold working (H-series tempers) or alloy composition alone. 5083 — with its 4.9% magnesium content — delivers 275 to 350 MPa tensile strength in the H116 temper without any heat treatment, making it one of the stronger non-heat-treatable alloys available.

Weldability is excellent across the 5xxx series. MIG and TIG welding with ER5356 or ER5183 filler wire achieves 90% or more of parent-metal strength in the weld zone, making 5xxx the natural choice for welded marine structures, pressure vessels, and tank construction.

5052 vs 5083: the key distinction

5052 (2.2 to 2.8% Mg) is the general-purpose marine-atmosphere alloy: fuel tanks, automotive panels, HVAC equipment, and applications requiring moderate corrosion resistance with good formability. 5083 (4.0 to 4.9% Mg) is the structural marine alloy: hull plating, bulkheads, offshore structures, and LNG cargo tanks where continuous seawater exposure and structural integrity are non-negotiable requirements.

The H116 and H321 tempers of 5083 are specifically engineered to resist exfoliation corrosion and stress-corrosion cracking in seawater. These tempers are accepted by all major classification societies including DNV, ABS, and Lloyd’s Register for hull plating certification.

Applications

• Ship hull plating, bulkheads, and marine structural components (5083-H116)

• LNG cargo tank walls: strength increases at cryogenic temperatures (−196°C)

• Fuel and water tanks, automotive body panels (5052-H32)

• Pressure vessels and storage tanks for chemicals and petroleum products

• Offshore platform structural components and naval vessel superstructures

→ Compare 5052 vs 6061 aluminum

→ Compare 5083 vs 5052 for marine applications

7. 6xxx Series: Aluminum-Magnesium-Silicon Alloys

The 6xxx series is the most widely used family of aluminum alloys in the world. By combining magnesium and silicon in the right proportions — which form the strengthening precipitate Mg2Si during aging — these alloys achieve an excellent balance of strength, corrosion resistance, formability, weldability, and machinability at a competitive price. 6061 and 6063 together account for the large majority of global aluminum extrusion volume.

6061: the structural workhorse

6061-T6 is arguably the most versatile structural aluminum alloy available. Its tensile strength of 310 MPa is adequate for the vast majority of industrial, transportation, and construction applications. It machines exceptionally well, welds with good results using ER4043 filler, and resists corrosion effectively in atmospheric and freshwater environments. When engineers specify “structural aluminum” without further qualification, 6061-T6 is almost always what they mean.

The T651 temper adds stress relief by stretching after solution heat treatment, producing plate with excellent dimensional stability for precision machining. For thick-plate machined components such as machine bases, fixture plates, and tooling, 6061-T651 is the standard specification.

6063: the architectural choice

6063 is optimized for extrusion rather than sheet, and its lower silicon and iron content produces a finer grain structure that anodizes to a cleaner, more transparent finish than 6061. These properties make 6063 the global standard for window frames, curtain wall systems, door frames, solar panel frames, and all architectural aluminum profiles where surface appearance is part of the design specification. The T5 temper (air-cooled directly from the extrusion press, then aged) delivers 186 MPa tensile strength at the lowest processing cost. T6 is specified where higher strength is needed.

Applications

• Structural frames, industrial racking, machine bases (6061-T6)

• Window and door frames, curtain wall systems (6063-T5)

• Solar panel frames and LED heat sinks (6063-T5)

• Precision machined components and tooling plates (6061-T651)

• Marine deck fittings and non-immersed structural components (6061-T6)

• Automotive structural parts and bicycle frames (6061-T6)

→ Compare 6061 vs 7075 aluminum

→ Compare 5052 vs 6061 aluminum

→ Compare 6061 vs 6063 for extrusion and architecture

8. 7xxx Series: Aluminum-Zinc Alloys

The 7xxx series achieves the highest static tensile strength of any common aluminum alloy family. Zinc is the primary alloying element (typically 5 to 8%), combined with magnesium and copper to form dense, fine precipitates (primarily MgZn2) that block dislocation movement with exceptional efficiency. 7075-T6 delivers 572 MPa tensile strength — approaching the strength of some structural steels at roughly one-third the weight.

Key properties

The extraordinary strength of 7xxx alloys comes with trade-offs. Corrosion resistance is poor, particularly for stress-corrosion cracking (SCC): 7075 in the T6 temper is among the most SCC-susceptible common aluminum alloys. Sustained tensile stress combined with humid or chloride environments can cause cracks to propagate at stress levels far below the static yield strength. The solution is temper selection: 7075-T73 and T7351 are over-aged to coarsen the grain boundary precipitates, dramatically reducing SCC susceptibility at a cost of approximately 12% tensile strength reduction.

Fusion welding is generally not recommended for 7xxx alloys due to hot cracking risk and significant HAZ strength loss. Friction stir welding is used in aerospace manufacturing where welded joints are required. Aerospace structures primarily use riveted and bolted connections.

Machinability is excellent. 7075-T6 and T651 are among the best-machining aluminum alloys, producing clean chip formation and good surface finishes at high cutting speeds.

7075 tempers: T6 vs T73

The temper choice for 7075 applications depends on the environment. T6 provides maximum strength (572 MPa) and is appropriate for indoor or dry environments where SCC is not a concern: UAV frames, sporting equipment, indoor structural fixtures. T73 and T7351 trade 12% strength for dramatically improved SCC resistance and are specified for outdoor structural fittings, landing gear, and any application with sustained tensile load in a humid or corrosive environment.

Applications

• Aircraft upper wing skin and primary structural fittings (7075-T6/T651): compression-loaded, strength-critical

• Landing gear components (7075-T73/T7351): high static load with SCC resistance required

• UAV and drone frames: maximum strength-to-weight ratio for lightweight aerial vehicles

• High-performance sporting goods: bicycle frames, climbing equipment, precision sports hardware

• Precision machined structural components: excellent machinability from plate or bar stock

9. How to Choose: Matching the Series to Your Application

The table below maps common applications to the recommended alloy series and specific grade. For detailed comparison of closely related alloys, follow the internal links to dedicated comparison articles.

Decision framework

• Start with the environment: marine saltwater immersion demands 5xxx; aerospace structure requires 2xxx or 7xxx; general industrial defaults to 6xxx or 3xxx

• Identify the governing property: if fatigue is the design driver, choose 2024 over 7075 even though 7075 is stronger statically; if surface finish drives the spec, 6063 outperforms 6061

• Check fabrication method: extrusions almost always use 6xxx; stamped sheet uses 1xxx, 3xxx, or 5xxx; precision-machined parts use 6061-T651 or 7075-T651

• Factor in cost: 1xxx and 3xxx are the most economical; 6xxx is the mid-range baseline; 2xxx and 7xxx carry a significant premium that is only justified when their unique properties are required

• Verify temper: the same alloy in the wrong temper can fail in service — confirm the temper designation alongside the alloy number in every specification

10. Aluminum Alloy Price Guide: Which Series Costs More and Why

Aluminum alloy prices are driven by raw material costs (the LME aluminum price plus alloying element costs), conversion premiums (rolling, heat treatment, certification), and market supply-demand dynamics. Here is a practical guide to relative pricing across the series.

Key price drivers by series

• 1xxx and 3xxx: The lowest conversion premium and commodity-scale production volumes keep these alloys at the lowest price point. 1100 carries a slight premium over 3003 because high-purity aluminum requires tighter refining controls.

• 5xxx: Magnesium is an affordable alloying element, but marine-grade 5083-H116 commands a premium due to the additional testing, temper control, and classification society certification required for hull plating applications.

• 6xxx: Heat treatment adds cost above 1xxx and 3xxx, but the broad demand and large production volumes keep 6061 at a moderate price. 6063 is often priced similarly to 6061 despite its simpler composition, because the extrusion premium applies to both.

• 2xxx and 7xxx: The copper and zinc alloying elements are more expensive than manganese or magnesium. More significantly, aerospace-grade production requires tighter composition control, more extensive mechanical testing, and full lot traceability — all of which add cost beyond the raw material premium. AMS-certified 7075-T651 or 2024-T351 plate can cost two to three times more per kilogram than 6061-T651.

11. Wrought vs Cast Aluminum: A Note on Scope

This guide covers wrought aluminum alloys — alloys that are mechanically worked (rolled, extruded, drawn, or forged) into flat-rolled sheet, plate, coil, and extruded shapes. The 1xxx through 7xxx designation system applies specifically to wrought alloys.

Cast aluminum alloys use a different designation system (A380, A356, ADC12, etc.) and are produced by pouring molten metal into moulds rather than mechanical working. Cast alloys are common in automotive engine components, pump housings, and complex near-net-shape parts, but they do not produce flat-rolled sheet or plate. If you are sourcing aluminum sheet, plate, coil, or extrusion, you are working with wrought alloys and the 1xxx–7xxx system applies.

12. We Supply All Major Aluminum Alloy Series

We supply flat-rolled aluminum sheet, plate, and coil across all the major alloy series covered in this guide. Our stock includes the most widely specified grades in the tempers and dimensions most commonly requested by industrial and commercial buyers.

• 1xxx series: 1100 in O, H14, H16, H18 — food-grade, sublimation-coated, and mill-finish available

• 3xxx series: 3003 in H14, H24, H32 — roofing coil, channel letter coil, and general sheet

• 5xxx series: 5052-H32, 5083-H116/H321 — marine plate with DNV/ABS/LR certification available

• 6xxx series: 6061-T6/T651, 6063-T5/T6 — structural sheet and plate, anodized finishes

• 7xxx series: 7075-T6/T651/T73 — commercial and AMS-certified material

• 2xxx series: 2024-T3/T351 — available with aerospace documentation on request

Cut-to-size service, surface treatment (anodizing, PE/PVDF coating, sublimation coating), and Mill Test Certificate documentation are available across all alloy families.

Contact us with your alloy, temper, thickness, width, length, and application requirements. We will respond within 24 hours with pricing and availability.