UK aluminium grades

Order the wrong aluminium grade and the problem doesn't show up straight away. It shows up six months later, as corrosion on a marine fitting that should have been 5083, or as a streaky, uneven finish on a window frame that needed a cleaner 6063 billet. By then, the metal's cut, fitted, and the mistake is expensive to undo.

That happens because the wrong grade either fails the job outright or costs more than it needed to. A splashback doesn't need structural strength, and a boat fitting doesn't need a decorative finish, so the grade has to match what the metal is actually being asked to do. This guide groups aluminium grades UK projects typically call for into three families based on the job, and if your project doesn't fit neatly into what follows, choosing the right aluminium grade covers the wider picture.

Three families cover almost every job; here's how to tell them apart.

1050A for Splashbacks & Decorative Work

1050A is what you reach for when looks and workability matter more than strength. It's a commercially pure aluminium, around 99.5 per cent aluminium with small amounts of iron and silicon making up the rest. That purity is what gives it three practical advantages.

What 1050A offers for decorative and surface work:

  • Takes a polish well and bends, folds, and cuts without much resistance.
  • Costs less to produce than the magnesium or silicon-rich grades further up the range.
  • Suits kitchen splashbacks, decorative trim, and any clean reflective finish without complicated fabrication.

What it won't do is carry a load, so framing that needs to hold weight calls for a different grade. An aluminium sheet cut to your exact measurements, with a tolerance of -0 mm to +2 mm, removes the need for any on-site trimming.

5083 & 5251 for Welding & Marine Environments

If the project involves welding, boats, or anything that's going to sit near salt air, 5083 or 5251 is the grade that holds up. Both are part of the 5000 series, alloyed with magnesium rather than heat-treated, which gives them their corrosion resistance and weldability. 5083 is the stronger and more widely available of the two, while 5251 is a step down in strength but still suited to general marine and outdoor fabrication, where 5083 would be overkill.

Both grades are also available as plate, which we stock in 6082, 5083, and 5251 alongside its HE30 and tooling grades, so the same comparison applies whether you're ordering bar or sheet stock.

Why 5083 Welds Cleanly When Other Grades Crack

5083 doesn't rely on heat treatment for its strength, so welding doesn't soften it as a 6000-series alloy would. The National Institute of Standards and Technology tested 5083-H131 and 7075-T6 in salt solutions and found that both alloys lost strength and ductility compared to dry conditions, with the drop larger in 5083 under the conditions tested [1].

The same research traced the cracking of the two alloys to different causes:

  • 7075 to the hydrogen absorbed into the metal.
  • 5083 to a dissolution reaction at the crack tip.

That distinction matters for welded marine structures because it's the dissolution mechanism, not hydrogen embrittlement, that governs 5083's behaviour under long-term saltwater exposure. Aluminium round bar in 5083 or 5251 is available cut to length for fabrication work.

6082 & 6063 for Structural & Anodised Work

6082 and 6063 are both 6000-series alloys, strengthened by heat treatment rather than alloying alone, and together they cover most structural and architectural aluminium work. The choice between the two comes down to what matters more, load-bearing strength or a clean anodised finish.

Beyond bar and angle, both alloys turn up regularly in architectural cladding work, where aluminium façade panels take advantage of the same strength-versus-finish trade-off covered here.

6082 for Load-Bearing Strength

6082 is the stronger of the two and the one to specify for frames, brackets, and anything carrying a real load. It machines well and holds its strength after fabrication, which is why it turns up across construction and general engineering work. Aluminium angles in 6082 are suitable for bracing, shelving frames, and structural support where strength is the priority.

6063 for Anodising & Clean Extruded Profiles

6063 trades some strength for a smoother extruded surface, and that surface is what makes it the standard choice for anodised window, door, and architectural trim frames.

A study of industrial 6063 extrusions found that visible streaking after anodising came down to magnesium-silicide particles left over from casting. Zones with fewer, larger particles develop wider, deeper etch pits than zones with more, smaller ones. Because etch pits are always larger than the particles that form them, even a small difference between two areas of the same extrusion shows up as a band of contrasting brightness once anodised [2].

Grain size, by contrast, did not make a measurable difference between the zones tested. In practice, that means the quality of a 6063 billet before extrusion has more bearing on a clean anodised finish than anything done afterwards. Aluminium channel in 6063 is a common choice for window tracking and edge framing.

Which Aluminium Grade Should You Order?

Right now, the grade question can feel like guesswork, since alloy numbers mean little until you know what they're for. Match the job to the right family, and the choice stops being a guess. This guide sorts every common job into one of three groups.

Match the job to the family, then refine by gauge and finish:

  • Splashbacks and decorative work point to 1050A.
  • Welding and marine exposure point to 5083 or 5251.
  • Structural framing and anodised finishes point to 6082 or 6063.

Click Metal stocks all four grades cut to your exact dimensions, with no minimum order and UK-wide delivery. With over 70 years of experience and a free cutting service, the team can talk you through close calls like 6082 against 6063 before you commit.

Call 01794 526090 or enquire online to get the right grade specified before you order.

External Sources

[1] National Institute of Standards and Technology (NIST), Richard E. Ricker, Eun Lee, R. Taylor, C. Lei, B. Pregger, E. Lipnickas, Chloride Ion Activity and Susceptibility of Al Alloys 7075-T6 and 5083-H131 to Stress Corrosion Cracking (2018): https://www.nist.gov/publications/chloride-ion-activity-and-susceptibility-al-alloys-7075-t6-and-5083-h131-stress

[2] PubMed Central (PMC), Juan Asensio-Lozano, Beatriz Suárez-Peña, George F. Vander Voort, Effect of Processing Steps on the Mechanical Properties and Surface Appearance of 6063 Aluminium Extruded Products (2014): https://pmc.ncbi.nlm.nih.gov/articles/PMC5455931/