An aluminium alloy number is not a stock code — it is a compressed statement about composition. The first of the four digits says which element was added to the aluminium, and therefore, indirectly: how much the alloy will take, how it behaves in contact with water, whether it can be welded and what a mill can make of it after remelting. Below is a guide to all eight series and to what follows from them once the material lands on the weighbridge.

How to read an aluminium alloy designation

Alloys for plastic working — profile, sheet, bar, tube, wire — are designated in Europe with the EN AW prefix and four digits, under EN 573-3. The abbreviation stands for European Norm Aluminium Wrought. Next to the digits you will often find the chemical notation in square brackets, for example EN AW-6060 [AlMgSi].

The digits read as follows:

  • First digit — the alloy family, that is the main alloying element. This is the one that carries most of the information.
  • Second digit — a modification of the base alloy; zero means the original variant. In the 1xxx series this digit describes control of impurities.
  • Last two digits — an identifier of the individual alloy within the family. The exception is the 1xxx series, where they state purity: 1050 means at least 99.50% aluminium, 1070 means 99.70%.
  • A trailing letter (2017A, 6005A) — a variant registered in Europe, with a composition slightly different from the American original.

Polish workshop practice still uses the older PN designations: PA38 is EN AW-6060, PA4 is 6082, PA6 is 2017A, PA11 is 5754, PA13 is 5083 and PA9 is 7075. A drawing marked PA4 therefore describes material from the 6xxx series.

1xxx series — commercially pure aluminium

Main addition: none — minimum 99% aluminium.

The softest and most ductile family, with the best electrical and thermal conductivity of the whole set and very good corrosion resistance. The price is low strength — in the range of 70–110 MPa, several times less than in structural alloys.

Where you meet it: busbars and power conductors, aluminium foil, heat exchangers, tanks and process equipment in the chemical and food industries, decorative sheet, heat sinks.

2xxx series — aluminium with copper (duralumin)

Main addition: copper, 2–6%.

Classic duralumin. Precipitation hardened, it reaches strength comparable with structural steel — 2024 in T3 temper is around 470 MPa — but pays for it with the worst corrosion resistance in the family and poor weldability. Hence the cladding with pure aluminium and the anodising on aerospace parts.

Where you meet it: aviation and defence, fasteners, tooling, and free-machining alloys for turning work (2007, 2011, 2030). PA6 on a workshop drawing is 2017A.

3xxx series — aluminium with manganese

Main addition: manganese, around 1–1.5%.

Not heat treatable — it is strengthened by cold work. Moderate strength (110–200 MPa) comes together with very good formability, weldability and atmospheric corrosion resistance. This is the most everyday family of aluminium sheet.

Where you meet it: roofing, gutters and flashings, radiators and heat exchangers, air conditioning, beverage can bodies (3004, 3104), cookware, and 3003 and 3103 sheet across hundreds of industrial uses.

4xxx series — aluminium with silicon

Main addition: silicon, 4–13%.

Silicon lowers the melting point and improves fluidity, which is why the 4xxx series rarely appears as a structural product — more often as a consumable. Alloy 4043 is the most widespread aluminium welding wire, and Al-Si layers on clad sheet act as the braze in heat exchangers. The structural exception is pistons (4032), which owe their wear resistance and low thermal expansion to silicon.

5xxx series — aluminium with magnesium (AlMg)

Main addition: magnesium, 0.5–5.5%.

The family with the best resistance to seawater and aggressive environments, not heat treatable, strengthened by cold work. Strength of 200–350 MPa combined with good weldability makes it a structural material wherever corrosion matters.

Where you meet it: hulls and superstructures of vessels, tankers and storage tanks, car body panels (5754 — the former PA11), welded structures (5083 — PA13), can ends (5182), anodised sheet (5005). In scrap buying this is the family known as AlMg sheet, separated by thickness and fraction size.

6xxx series — aluminium with magnesium and silicon

Main addition: magnesium and silicon together.

The most important family in everyday scrap practice. Heat treatable, with strength of 150–330 MPa, good corrosion resistance and weldability — but above all outstandingly suited to extrusion. The vast majority of aluminium profile worldwide is made from this series.

Where you meet it: window and door joinery and façades (6060 and 6063, that is PA38), load-bearing structures, trailers, cranes and bridges (6082, that is PA4), rail vehicles (6005A), general-purpose profile and plate (6061), free-machining bar with bismuth and lead additions (6262).

A shared family does not mean a shared grade in scrap buying, though. We take 6060 joinery profile and 6082 structural profile separately, because they feed different melts — mixed together they settle as the weaker grade, not as an average of the two.

It is also the material mills want most: clean 6xxx scrap comes back from the melt as an extrusion billet, that is, into the same application it came from. We write more about that loop in our piece on aluminium recycling in a closed loop.

7xxx series — aluminium with zinc

Main addition: zinc, 4–8%, usually with magnesium and copper.

The strongest aluminium alloys there are — 7075 in T6 temper reaches about 570 MPa, the level of medium-strength steel at one third of the mass. The cost is susceptibility to stress corrosion cracking and difficult welding (the weldable 7020 being the exception).

Where you meet it: aerospace structures, sports and climbing equipment, bicycle frames, injection moulds, armour components. Workshops know it as "dural" or PA9.

8xxx series — other elements

Main addition: everything that does not fit the previous families.

The most heterogeneous group. Its largest share is taken by foil alloys with iron and silicon — 8011 and 8079 are packaging and household foil, 8006 goes into deep drawn products. A separate branch is aluminium-lithium alloys (8090), lighter and stiffer than ordinary aerospace grades.

Casting alloys have their own designations

Everything above concerns wrought alloys. Castings are designated differently: with the EN AC prefix and five digits, under EN 1706 — for example EN AC-46000 [AlSi9Cu3(Fe)], the most common high-pressure die casting alloy, or EN AC-42000 [AlSi7Mg], which most aluminium wheels are made from.

The difference is not formal but physical: casting alloys contain 9 to 12% silicon, whereas in wrought alloys silicon rarely exceeds 1–2%. Silicon improves fluidity and mould filling, but it also means a casting cannot serve as feedstock for profile. That is the first reason castings and profiles are settled as two separate grades.

The letter after the number: the temper

A full product designation carries one more suffix describing the condition after processing, under EN 515:

  • F — as fabricated, no controlled treatment.
  • O — annealed, the softest and most ductile state.
  • H (H14, H24) — strain hardened; the digits state the degree of hardening and whether the material was annealed or stabilised afterwards.
  • T (T4, T5, T6, T66) — heat treated: solution treated and naturally aged (T4) or artificially aged (T6), or cooled straight from the extrusion temperature and aged (T5).

For a designer this is essential information. For scrap valuation it is irrelevant. The temper changes the hardness of the finished product but not the chemical composition, and it disappears on remelting. A 6060-T66 profile and a 6060-T5 profile are the same material in scrap buying.

What the series means in scrap buying

A mill buys composition, not appearance. And composition obeys one simple, unforgiving rule: alloying elements can be added to a melt, but in practice they cannot be taken out of it. Copper from the 2xxx series, zinc from the 7xxx series or silicon from castings will not be melted out of liquid aluminium — the only way to lower the concentration is dilution with primary metal, and primary costs several times more than scrap.

Four practical conclusions follow:

  • Keep profile separate from castings. This is the most common and most expensive mistake on the heap: silicon from castings closes the route back to an extrusion billet.
  • Set aside aerospace, sports and "dural" parts. Alloy 6060 permits at most 0.15% zinc while 7075 carries over 5% — on the order of a hundred kilograms of dural in five tonnes of profile is enough to push the batch out of spec.
  • Separate turnings by machine and by alloy. For the same reason we do not take turnings from 7xxx alloys or from free-machining alloys with bismuth in this grade — bismuth binds magnesium into hard phases and degrades the product.
  • Steel and iron are worse than they look. Screws, hinges and embedded bushings bring in iron, which forms brittle AlFeSi phases and is equally impossible to remove. That is why clean profile settles higher than profile with its hardware still on.

Material sorted by alloy family returns to the same application. Mixed material goes into silicon-rich casting alloys — still recycling, but one class down and for less money. That gap is the whole case for sorting at source, which we cover in more detail in our guide to aluminium grades in scrap buying.

Quick reference: where you meet each series

  • 1xxx — power cable, foil, heat exchangers, chemical tanks.
  • 2xxx — aviation, fasteners, free-machining bar.
  • 3xxx — roofing, gutters, radiators, cans, air conditioning.
  • 4xxx — welding wire, exchanger braze layers, pistons.
  • 5xxx — AlMg sheet, car bodies, tankers, marine vessels.
  • 6xxx — window and façade profile, structures, trailers, machinery.
  • 7xxx — dural, sports equipment, bicycle frames, moulds.
  • 8xxx — packaging and household foil, aerospace lithium alloys.
  • EN AC-4xxxx — castings: housings, cylinder heads, wheels, gearbox casings.

You do not have to identify the series yourself — that is what branch staff are for. We assess the grade visually and by the characteristics of the material, and where the alloy is not obvious we confirm the composition with a handheld spectrometer. Do you have a steady waste stream from production? Send photos and an approximate tonnage and we will price your aluminium by its actual alloy family rather than an averaged rate.