3002 H112 Aluminium Extrusions for Automotive Trim
3002 is a high-purity aluminium alloy with tiny, controlled additions of manganese and magnesium, designed to give a brilliant, uniform finish after chemical or electrolytic brightening and anodising. It is used for decorative automotive trim rather than structural parts. Metline supplies 3002 extrusions and sheet in the H112 and other tempers to trim makers worldwide.
- Alloy
- 3002 (high-purity Al-Mn-Mg)
- Temper
- H112, O, H1x
- Finish
- Bright dip / electropolish + anodise
- Use
- Decorative trim, mouldings
What is 3002 aluminium?
3002 is unusual in the 3xxx series. Most 3xxx alloys, such as 3003, contain about 1 – 1.5 % manganese for strength. 3002 instead starts from very pure aluminium, with iron and silicon each limited to around 0.1 % or less, and adds only small amounts of manganese and magnesium. The result is an alloy whose surface brightens to a mirror-like, colourless finish.
The reason is metallurgical. Iron- and silicon-rich particles in ordinary aluminium scatter light and make an anodised film cloudy or grey. By keeping those impurities very low, 3002 produces a clear anodic film over a highly reflective metal surface. The small manganese and magnesium additions give a little more strength and grain control than pure 1xxx metal while preserving that brightness.
In automotive use, 3002 belongs with the bright-trim family alongside 5252, 5457, 5657 and 6463. It suits window surrounds, roof-rail caps, grille surrounds, badges, bright mouldings and interior trim strips, where appearance matters far more than structural strength.
3002 chemical composition (wt %)
| Element | Minimum | Maximum | Why it matters |
|---|---|---|---|
| Silicon (Si) | — | 0.08 | Kept very low to avoid dulling particles |
| Iron (Fe) | — | 0.10 | Kept very low for clarity of the anodic film |
| Copper (Cu) | — | 0.15 | Small amounts aid brightening |
| Manganese (Mn) | 0.05 | 0.25 | Grain control and modest strength |
| Magnesium (Mg) | 0.05 | 0.20 | Modest strength |
| Zinc (Zn) | — | 0.05 | |
| Titanium (Ti) | — | 0.03 | |
| Vanadium (V) | — | 0.05 | |
| Aluminium (Al) | Remainder | High-purity base |
Composition as published for the registered alloy; confirm the edition your drawing uses. The certificate reports the actual analysis, which is essential for bright-finish work because small changes in iron alter the colour.
Mechanical and physical properties
With less than 0.5 % total alloying content, 3002 behaves mechanically much like commercially pure aluminium: soft, ductile and easily formed, with strength in the same low range as 1100 and below that of 3003. It cannot be heat-treated; strength comes only from cold work.
| Property | 3002 | 1100 (reference) | 3003 (reference) |
|---|---|---|---|
| Strength level, H112 / O | Low (similar to 1xxx) | ~ 75 – 90 MPa tensile | ~ 110 MPa tensile (O) |
| Formability | Excellent | Excellent | Very good |
| Bright-finish quality | Excellent | Fair (cloudier film) | Poor (grey film) |
| Corrosion resistance | Very good | Very good | Very good |
Some data sheets quote 180 – 220 MPa tensile strength for 3002-H112 extrusions. That is not credible for an alloy this dilute in the as-extruded condition; design with values comparable to 1xxx alloys and confirm by test if strength matters. Choose 5657, 5457 or 6463 when more strength is required with a bright finish.
Physical properties (approximate)
- Density
- about 2.70 g/cm³
- Thermal conductivity
- high, above 200 W/m·K
- Melting range
- about 640 – 655 °C
How 3002 trim is brightened and anodised
- Mechanical polish or buffExtrusions or formed parts are polished to remove die lines and handling marks.
- Chemical or electrolytic brighteningPhosphoric-nitric bright dipping or electropolishing levels the surface on a microscopic scale and raises specular reflectance.
- AnodiseA thin, clear sulphuric-acid anodic film, typically about 3 – 10 µm for bright trim, protects the bright surface without clouding it.
- SealHot-water or other sealing closes the pores and improves corrosion and stain resistance.
- Optional colourDyeing or electrolytic colouring before sealing gives bronze, black or other tones.
Thicker anodic films improve durability against road salt and car-wash chemicals but slightly reduce brightness. Agree film thickness and test requirements, for example CASS or neutral salt spray and alkaline resistance, with your vehicle maker.
3002 extrusion and sheet supply
Typical supply range
- Profiles
- Trim sections, channels, caps, round and rectangular tube to drawing; typically within a 10 – 250 mm envelope
- Wall thickness
- From about 0.5 mm for trim sections
- Sheet and strip
- Thin gauges for stamped badges and roll-formed mouldings
- Tempers
- H112 (extrusions), O and H1x (sheet and drawn products)
- Surface protection
- Interleaved or film-protected to preserve decorative surfaces
Bright-trim extrusions need a "decorative surface" classification on the drawing that identifies the significant surfaces.
Automotive uses of 3002
- Exterior bright trim: window and door belt mouldings, roof-rail caps, grille surrounds
- Badges and emblems: stamped and brightened sheet parts
- Interior trim: dashboard and door inserts, speaker grille frames, sill plates
- Lighting: reflector components and lamp bezels
- Commercial vehicles: decorative strips on buses and coaches
3002 is not used for body structure, engine or chassis parts. Load-bearing extrusions use 6xxx alloys such as 6063, 6061 and 6082.
3002 compared with other bright-trim alloys
| Alloy | Base | Strength | Brightness | Typical form |
|---|---|---|---|---|
| 3002 | High-purity Al + low Mn, Mg | Low | Excellent | Extrusions, sheet |
| 5657 | High-purity Al + ~0.8 % Mg | Low – moderate | Excellent | Sheet, extrusions |
| 5457 | Al + ~1 % Mg + Mn | Moderate | Very good | Sheet, extrusions |
| 5252 | Al + ~2.5 % Mg | Moderate | Very good | Sheet for trim and bumper covers |
| 6463 | Al-Mg-Si, low Fe | Moderate – good (heat-treatable) | Very good | Extrusions |
For trim that must also carry load or be clipped tightly, 6463 gives a good bright finish with heat-treatable strength.
How to order 3002 extrusions
- SpecifyAlloy and temper (3002-H112), profile drawing with significant surfaces, length, quantity and finishing route.
- Confirm the standardYour drawing and appearance standard; ASTM B221 or EN 755-9 for dimensional tolerances.
- QuoteWe confirm availability, tolerances, certification and delivery terms (EXW, FOB, CIF or DAP) for your plant or port.
- Process and inspectProfiles are inspected for dimensions and surface quality and packed with interleaving to protect decorative faces.
- Document and shipEach lot ships with an EN 10204 3.1 mill test certificate, heat or lot traceability and a packing list, in seaworthy export packing. Third-party inspection can be arranged on request.
References and standards
- The Aluminum Association – International Alloy Designations and Chemical Composition Limits (Teal Sheets)
- ASTM B221 – Aluminum and Aluminum-Alloy Extruded Bars, Rods, Wire, Profiles, and Tubes
- EN 573-3 – Aluminium and aluminium alloys: chemical composition and form of wrought products
- Aluminum Anodizers Council – Alloys suitable for anodizing
- ASM Handbook, Vol. 5 – Surface Engineering: chemical brightening and anodizing of aluminum
3002 aluminium (aluminum) for automotive trim: frequently asked questions
What is 3002 aluminium used for?
Decorative parts that are brightened and anodised, such as automotive trim, mouldings, badges and reflectors. It is chosen for appearance, not strength.
Why does 3002 anodise brighter than 3003?
3003 contains about 1.2 % manganese and more iron, which form particles that make the anodic film grey. 3002 has very low iron and silicon and only traces of manganese, so the film stays clear.
Is 3002 strong enough for structural parts?
No. Its strength is similar to commercially pure aluminium. Use 6063, 6061 or 6463 where the trim must carry load.
What does H112 mean for 3002 extrusions?
As extruded, with only incidental strain hardening and no further thermal treatment. It is the normal temper for 3002 profiles.
Can 3002 be coloured?
Yes. After brightening and anodising, the film can be dyed or electrolytically coloured before sealing.
Does Metline supply 3002 internationally?
Yes. Metline supplies 3002 extrusions and sheet to order worldwide with certificates and protective export packing.
Making bright trim?
Send the profile drawing, finish and quantity. Our team will confirm feasibility and send a delivered quotation.
