What 3003 is
3003 is aluminium with manganese as the main addition, typically 1.0-1.5%, plus a small copper content. The manganese lifts strength above the 1xxx pure grades without the magnesium that gives 5052 its higher strength and slightly lower ductility. Like the 3xxx and 5xxx families, it is non-heat-treatable: strength comes from cold work, so the temper designation is the lever rather than a quench.
In sheet metal work it appears where a part must be formed deeply — a drawn cover, a rounded housing, a bracket with a tight inside radius — or where a low-cost alloy is wanted and the mechanical demand is modest.
Typical properties for engineering reference
Typical values for sheet in common tempers. Actual values vary by temper and by mill.
| Property | Typical value |
|---|---|
| Alloy content | ~1.0-1.5% Mn, small Cu addition |
| Tensile strength (O / H14) | ~110-145 MPa / ~145-185 MPa |
| Yield strength (O / H14) | ~40-50 MPa / ~125-150 MPa |
| Elongation (O) | ~25-30% — excellent for deep forming |
| Density | 2.73 g/cm3 |
| Heat treatable | No — cold work only |
| Weldability | Good, all common processes |
| Corrosion resistance | Good in atmosphere; not for marine service without a finish |
Where it fits, and where it does not
3003 sits below 5052 in strength and below 6061 in everything that follows from heat treatment. Against 1100 it is the better default: similar forming behaviour, more strength, comparable cost. The honest summary is that 3003 is chosen for the forming operation first and the mechanical duty second.
It is the wrong choice where a part must carry load, where the environment is aggressive, or where an anodised structural finish is wanted. For a bent enclosure seeing coastal air, 5052 is the more durable answer. Where the part is a machined structural component, 6061-T6 is the only one of the three that qualifies.
Fabrication notes
3003 forms beautifully: tight inside radii that would tear 6061-T6 are routine, and deep draws that would need an intermediate anneal in 5052 are done in one operation. Laser cutting is straightforward and the soft cut edges deburr easily.
Welding is standard, with the usual aluminium caveats — surface oxide removed before welding and filler matched to the parent. Where the part will be finished, anodising responds normally, although the manganese content gives a slightly greyer tone than pure aluminium, which matters on decorative work matched to a sample.