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Aluminum Alloys

Aluminum is the default metal for parts that must be light, corrosion resistant and quick to machine: a third the density of steel, steel-like strength in the 7000 series, and most grades anodize. Strength spans a 50× range from the 1000 to the 7000 series, so the series and temper matter more than the word on the drawing.

CAD render of a machined aluminum fixture base with a stepped pocket, mounting holes, side threads and fine facing marks.

Aluminum by series

1000 series≥ 99 % pure Al2612 – 165Bus bars, chemical tanks, reflectors
2000 seriesCopper65110 – 610Aerospace structure; not weldable
3000 seriesManganese1135 – 275Sheet metal, roofing, cookware, cans
4000 seriesSilicon2745 – 315Weld filler, brazing sheet, forged pistons
5000 seriesMagnesium5368 – 331Marine, pressure vessels, welded structure
6000 seriesMg + Si5541 – 380Machined parts, extrusions, frames
7000 seriesZinc4221 – 683Aircraft fittings, molds, racing parts
8000 seriesLi, Fe, others1535 – 480Foil (8011), Al-Li aerospace (8090)
CastSi, Cu, Mg18455 – 460Die-cast housings, pump bodies, brackets
Tooling & mold plateCast plate1183 – 495Fixtures, jigs, prototype molds
AdditiveSi, Mg, Sc6240 – 310Powder-bed parts: heat exchangers, brackets
Other aluminumVarious230 – 320Proprietary, clad and specialty grades

Choose aluminum for

Housings, brackets, heat sinks, enclosures, fixtures and any structural part where weight or thermal conductivity matters and the service temperature stays under about 150 °C. A 6061 bracket machines three to four times faster than the same part in 304 stainless, and the part is a third of the weight.

Look elsewhere when

Sustained heat above ~200 °C (use steel, titanium or a nickel alloy), fatigue at high stress, wear (hardened steel), or a high-strength weld: 2000 and 7000 series are generally non-weldable, and a welded 6061-T6 joint keeps about half its strength unless re-heat-treated.

Yield strength against elongation at break, every aluminum grade

No materials in view have both of these properties.

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Aluminum by application

Everyday machined parts
6061-T6 unless there is a reason not to. 6082 is the EN equivalent; 6262 and 6020 for screw-machine work.
Aerospace structure
7075-T6 and 7050-T7451 for fittings and ribs, 2024-T3 for fatigue-loaded skins, 2195 and 8090 where every gram counts.
Marine and welded structure
5083-H116 and 5086 for hulls and tanks; 5052 for lighter sheet work. Weld with 5356 filler.
Electrical conductors
1350 for bus bar (61 % IACS); 6101-T6 where the conductor also carries load.
Heat exposure to ~250 °C
Forged pistons and compressor wheels — still far below steel, so check the temperature first.
Cast housings in volume
A380 for die casting; A356 and A357 for heat-treated structural castings.
Fixtures, jigs, prototype molds
MIC6 and ATP-5 for flatness; QC-10 and Hokotol when the mold must run thousands of shots.

Manufacturing notes

CNC machining

D = 6 mmPlan view · exaggerated

Feed per tooth mm/tooth

Ø6 mm · 3-flute carbide end mill

Distance the cutter advances between successive teeth (chip load). Published per material; independent of tool diameter.

Polycarbonate has the highest feed per tooth (0.0762 mm/tooth); 304 and Ti-6Al-4V the lowest (0.0127 mm/tooth).

n = 1,000 vc / (πD)vf = fz × z × nD = 6 mm · z = 3 flutes · diagram not to scale

Aluminum is the fastest metal we cut. 6061, 6082, 7075 and 2024 all hold tight tolerances; 6262 and 2011 are the free-machining grades for high-volume turned parts. Long thin walls in 6061 move after machining — we stress-relieve, or pick 7075 or MIC6 when flatness is on the drawing.

Sheet metal

Minimum inside radius mm

Smallest published inside radius for a 90° bend at the selected sheet thickness.

6061-T651 has the highest minimum inside radius at 1.6 mm (5.6 mm); 3003-H14 the lowest (0 mm).

Rᵢ = (Rᵢ/t) × tt = sheet thicknessOutside radius = Rᵢ + t90° bends · grain direction and temper matter

5052-H32 is the standard bend-and-weld sheet; 3003 for deep forming. 6061-T6 sheet cracks on tight bends unless it is bent in T4 and aged afterwards.

Casting
A380 for die casting; A356-T6 for sand and investment castings that will be heat-treated.
3D printing
AlSi10Mg on powder-bed fusion; Scalmalloy or 7A77 when strength must approach wrought 7000-series alloys.
Finishing
Type II anodize (clear or dyed) on 5000 and 6000 series; Type III hardcoat for wear; chem-film (MIL-DTL-5541) where conductivity must stay; bead blast, powder coat, paint. 2000 and 7000 series anodize darker and less evenly; high-silicon cast alloys anodize gray.

Finishes for aluminum

All 111 finishes

88 of our 111 surface finishes take aluminum: 41 recommended outright, 20 with process care, 27 in limited cases. Each finish opens to its datasheet — thickness, hardness, salt-spray hours, spec codes and the aluminum-specific notes — and the configurator prices it on the grade you pick.

Illustrative CAD render of the same aluminum fixture with visible milling marks.
As-machined
Illustrative CAD render of the same aluminum fixture with a matte bead-blasted surface.
Bead blasted
Illustrative CAD render of the same aluminum fixture with a black anodized surface.
Black anodized
FinishGroupOn aluminumThickness, µmHardness, HVSalt spray, hCost
Anodizing Type IIAnodizing, conversion & passivationYes5–25200–400336$$
Chemical Conversion CoatingAnodizing, conversion & passivationYes0.1–1.5—168$
Hard Anodizing Type IIIAnodizing, conversion & passivationYes25–75350–550336$$$
Copper PlatingPlating & metallizingWith care5–3050–250—$$
Decorative Nickel-Chrome PlatingPlating & metallizingWith care0.3–1700–1,00096–500$$$
Electroless Nickel PlatingPlating & metallizingWith care5–75450–1,000100–1,000$$$
CerakotePaint, powder & polymer coatingsYes20–30—500–1,000$$$
Electrophoretic CoatingPaint, powder & polymer coatingsYes15–35—500–1,000$$
Epoxy CoatingPaint, powder & polymer coatingsYes50–200—500–1,000$$$
HVOF Carbide CoatingPVD, CVD & thermal sprayWith care50–5001,000–1,400—$$$$
Plasma Spray CoatingPVD, CVD & thermal sprayWith care50–500500–900—$$$$
Aluminum Chromium Nitride PVDPVD, CVD & thermal sprayLimited1–52,900–3,400—$$$$
Bead BlastingMechanical finishing & post-processingYes0——$
Brushed FinishMechanical finishing & post-processingYes0——$$
DeburringMechanical finishing & post-processingYes0——$
Chemical EtchingMarking, decoration & colourYes5–100——$$$
Dot Peen MarkingMarking, decoration & colourYes50–500——$
Embossing and DebossingMarking, decoration & colourYes200–1,000——$$$

70 more finishes accept aluminum — see the full material × finish matrix →

Aluminum — frequently asked

Is 6061 or 7075 better for a machined part?

6061-T6 for almost everything: it costs about a third as much, machines faster, welds and anodizes cleanly. Step up to 7075-T6 only when the design needs its roughly 80 % higher yield strength and the part will not be welded.

Which aluminum is "aerospace grade"?

Mostly the copper-bearing 2000 series (2024, 2124, 2219) and zinc-bearing 7000 series (7075, 7050, 7175), plus the Al-Li grades 2195, 2060 and 8090. 6061 is used in aircraft too, but for brackets and non-critical structure — it is not what a drawing means by "aerospace aluminum".

Which aluminum resists saltwater?

The 5000 series — 5083, 5086 and 5052 — is the marine standard: it is not heat-treatable, so there are no copper-rich phases to corrode, and it welds well. Avoid 2000 and 7000 series in salt spray unless they are clad or coated.

Can aluminum be welded?

1000, 3000, 5000 and 6000 series weld readily (TIG or MIG with 4043 or 5356 filler). Heat-treatable 6000 series loses strength in the weld zone; 2000 and 7000 series are generally considered non-weldable for structural use — design those parts as one machined piece or fasten them.

How much does aluminum cost compared with steel?

Per kilogram aluminum costs more, but a part is one-third the weight and machines several times faster, so for machined parts the finished piece is usually cheaper or equal. The 5000 and 6000 series are the cheapest aluminum; the aerospace 2000 and 7000 series cost several times more per kilogram. Upload the part for a priced comparison.