T6 / T6511
Solution heat-treated, quenched and artificially aged; T6511 is also stretched and may receive minor straightening. Uniform properties for profiles and tubes.
Weldable high-strength extrusion
7005 T6 Automotive Aluminium Profile
7005 is an aluminium-zinc-magnesium alloy designed for welded structures: it extrudes into tubes and profiles, welds without filler cracking problems when the right wire is used, and regains strength in the weld zone by natural ageing. In T6 and T53 it gives around 290 – 345 MPa yield, making it a popular choice for vehicle frames, trailers, motorcycle and bicycle frames. Metline supplies 7005 profiles and tubes to drawing, worldwide.
- Alloy
- 7005 (Al-Zn-Mg-Mn-Zr)
- Tempers
- T6, T53, T5
- Min. yield (T53)
- 303 MPa (ASTM B221)
- Strength
- Weldable; HAZ recovers by ageing
Why 7005 is used for welded vehicle structures
Most high-strength aluminium alloys lose much of their strength next to a weld. 7005 is different: its zinc-magnesium precipitates dissolve in the heat-affected zone and then re-form at room temperature, so a welded 7005 frame steadily recovers strength over the weeks after welding, without a full re-heat treatment.
The alloy carries about 4.5 % zinc and 1.4 % magnesium, with manganese, chromium and zirconium to control grain structure. Copper is kept very low, which helps weldability and general corrosion resistance. 7005 is moderately quench-insensitive, so it can be supplied as T5 or T53 (press-quenched and aged) as well as the fully heat-treated T6.
In vehicles, 7005 is used where 6061 or 6082 would be heavier and where the structure is fabricated by welding: frames, sub-frames, trailer chassis, roll cages, racks and battery-protection members. It is also a classic bicycle and motorcycle frame tube alloy, which gives a large base of proven welding practice.
7005 chemical composition (wt %)
Registered Aluminum Association limits, also used in EN 573-3 for EN AW-7005. Some published tables show 7005 with 1 – 2 % copper and 0.35 – 0.80 % silicon; those values are incorrect for this alloy, whose copper limit is 0.10 % maximum.
| Element | Minimum | Maximum | Role |
|---|---|---|---|
| Zinc (Zn) | 4.0 | 5.0 | Strengthening with Mg |
| Magnesium (Mg) | 1.0 | 1.8 | Strengthening with Zn |
| Manganese (Mn) | 0.20 | 0.70 | Grain-structure control, toughness |
| Chromium (Cr) | 0.06 | 0.20 | Grain control, SCC resistance |
| Zirconium (Zr) | 0.08 | 0.20 | Inhibits recrystallisation |
| Titanium (Ti) | 0.01 | 0.06 | Grain refiner |
| Copper (Cu) | — | 0.10 | Kept low for weldability |
| Silicon (Si) | — | 0.35 | Impurity |
| Iron (Fe) | — | 0.40 | Impurity |
| Others, each / total | — | 0.05 / 0.15 | |
| Aluminium (Al) | Remainder |
Mechanical properties of 7005 extrusions
7005 does not reach 7075-type strengths; claims of 500 MPa or more for 7005-T6 are not realistic. The values below reflect published typical data and ASTM B221 minimums.
| Temper / basis | Tensile strength | Yield strength (0.2 %) | Elongation |
|---|---|---|---|
| T53, specified minimum (ASTM B221, thin sections) | 345 MPa / 50 ksi | 303 MPa / 44 ksi | 10 % |
| T53, typical | about 390 MPa | about 340 MPa | about 15 % |
| T6 / T6511, typical | about 350 MPa | about 290 MPa | about 13 % |
Physical properties (typical)
- Density
- 2.78 g/cm³
- Modulus of elasticity
- about 71 GPa
- Thermal conductivity
- about 140 – 150 W/m·K
- Coefficient of thermal expansion
- about 23 µm/m·°C
- Melting range
- about 605 – 645 °C
7005 tempers explained
T53
Cooled from the extrusion temperature and given a controlled artificial ageing. Higher strength than T6 in thin sections and a common choice for frame tubing.
T5
Press-quenched and aged; a cost-effective temper for open profiles where the highest strength is not required.
As-welded condition
After welding, store assemblies at room temperature for several weeks, or apply an agreed artificial ageing cycle, before full loading.
7005 standards and supply range
| System | Designation | Typical product standard |
|---|---|---|
| Aluminum Association / UNS | 7005 / A97005 | ASTM B221 (extrusions and tube) |
| European (EN) | EN AW-7005 / AlZn4.5Mg1.5Mn | EN 755-2, EN 573-3 |
| China (GB) | 7005 | GB/T 3190, GB/T 6892, GB/T 33910 |
| Section | Typical size range |
|---|---|
| Round tube | OD about 10 – 300 mm, wall 1 – 20 mm |
| Square tube | About 10 × 10 to 150 × 150 mm, wall 1 – 10 mm |
| Rectangular tube | About 10 × 20 to 200 × 300 mm, wall 1 – 10 mm |
| Angle, channel and custom profiles | To drawing |
7005 T6 profile supply range
- Section types
- Open profiles (angle, channel, T, hat), single- and multi-cell hollows, round, square and rectangular tube, solid bar
- Circumscribing circle
- Typically up to about 250 – 300 mm for 7xxx; larger sections reviewed case by case
- Wall thickness
- From about 1.5 – 2 mm for hollows, depending on section complexity
- Length
- Mill lengths of 3 – 7 m, or cut to exact length, bent, punched or machined on request
- Surface
- Mill finish, anodised, e-coated, powder coated or prepared for chrome or paint
- Documents
- EN 10204 3.1 certificate, dimensional report, PPAP-style records on request
Extrusion dies are made to your drawing. Send the section with critical dimensions and tolerances.
Welding, forming and protection
Welding
TIG and MIG weld well with ER5356 or ER5556 filler. Avoid 4043: silicon-rich weld metal on Al-Zn-Mg base gives low ductility. Keep heat input low, clean the oxide immediately before welding and allow natural ageing before proof loading.
Stress corrosion
Like all Al-Zn-Mg alloys, 7005 can crack under sustained tensile stress in damp or salty service if the temper, residual stress and grain structure are wrong. Specify a controlled ageing practice, avoid cold forming after ageing, keep assembly stresses low, and ask for SCC test data (for example ASTM G47 alternate immersion) on critical parts.
Forming and bending
Stretch bending and rotary-draw bending are best done in the freshly quenched (W) or T4 condition, then aged to T5 or T6. Bending in the fully aged condition needs generous radii and raises residual stress.
Machining
Machines more cleanly than 6xxx alloys in the aged condition, with short chips and a good finish using sharp carbide tools and flood coolant.
Surface finishing
Accepts anodising, e-coating and powder coating. Zinc-rich alloys anodise with a slight yellow-grey tint, so check colour needs for visible parts. Coatings also add a barrier against galvanic and stress corrosion.
Joining to steel
Isolate 7005 from steel, carbon fibre and copper with sealants, coatings or insulating washers, and use coated fasteners, to avoid galvanic corrosion in wet road environments.
Automotive uses of 7005
- Frames and sub-frames: welded tubular structures for specialist, off-road and racing vehicles
- Trailers and truck bodies: chassis rails, cross-members and ramp frames
- Two-wheelers: motorcycle and bicycle frame tubes, swing arms and handlebars
- Racks and carriers: roof rails, ladder racks and cargo-management members
- EV structures: battery-pack frames and protection members where welding is used
- Rail and bus: welded body frames and floor members
7005 is an extrusion and tube alloy. It is not normally used for cylinder heads, crankcases or cast wheels, which are made from casting alloys such as A356, nor for outer body panels, which use 5xxx and 6xxx sheet.
7005 compared with 6061, 7003 and 7020
| Property | 7005-T6 | 6061-T6 | 7003-T5 | 7020-T6 |
|---|---|---|---|---|
| Typical yield strength | about 290 MPa | about 276 MPa | about 300 MPa | about 280 – 320 MPa |
| Weld-zone recovery by natural ageing | Yes | No | Yes | Yes |
| Post-weld heat treatment needed | Usually no | For full strength | Usually no | Usually no |
| SCC sensitivity | Moderate | Very low | Moderate | Moderate |
| Typical market | Frames, tube | General | Bumper beams | Welded structures (Europe) |
7020 is the closest European relative and is often specified interchangeably for welded structures; see our 7020 tube page.
How to order 7005 automotive profiles
- SpecifyAlloy and temper (7005-T6 or T53), section or tube size, length, quantity and any cutting, bending or machining.
- Confirm the standardASTM B221, EN 755-2, GB/T 33910 or your OEM specification.
- QuoteWe confirm availability, tolerances, certification and delivery terms (EXW, FOB, CIF or DAP) for your plant or port.
- Process and inspectProfiles are extruded, heat-treated, straightened, cut, inspected and tensile-tested per lot.
- Document and shipEach lot ships with an EN 10204 3.1 mill test certificate and packing list, in seaworthy export packing by sea or air; third-party inspection 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 755-2 – Extruded rod/bar, tube and profiles: mechanical properties
- EN 573-3 – Aluminium and aluminium alloys: chemical composition and form of wrought products
- The Aluminum Association – Aluminum Design Manual (welded properties of 7005)
- ASTM G47 – Determining Susceptibility to Stress-Corrosion Cracking of 2XXX and 7XXX Aluminum Alloy Products
7005 automotive aluminium (aluminum) profiles: FAQ
Is 7005 stronger than 6061?
Moderately. Typical 7005-T6 yield is about 290 MPa against 276 MPa for 6061-T6, and T53 reaches about 340 MPa. The bigger advantage is in welded parts, where 7005 recovers strength by natural ageing.
Do 7005 frames need heat treatment after welding?
Usually not. The weld zone regains much of its strength at room temperature over several weeks. Some makers apply a short artificial ageing cycle to speed this up.
Which filler wire should be used for 7005?
ER5356 or ER5556. Avoid ER4043, which gives brittle welds on Al-Zn-Mg alloys.
What is 7005-T53?
A temper where the extrusion is cooled from the press and then given a controlled artificial ageing. ASTM B221 guarantees 345 MPa tensile and 303 MPa yield for thin sections.
Is 7005 suitable for engine parts?
No. Engine blocks and heads are cast alloys. 7005 is used for extruded and welded structures.
Can you supply 7005 tube cut to length?
Yes, cut to length and deburred, with mill certificates, shipped worldwide.
Building a welded frame in 7005?
Send tube sizes or profile drawings and quantities. We will confirm availability, certification and a delivered price.
