T6
Solution heat-treated, quenched and aged to peak strength. Suits beams that are cut and machined but not heavily straightened.
GB/T 33910 automotive alloy
7A46 T6 / T651 / T7651 Automotive Aluminium Profile
7A46 is a Chinese-standard Al-Zn-Mg-Cu extrusion alloy listed in GB/T 33910, the national specification for aluminium profiles used in motor vehicles. In the peak-aged condition it is specified at a minimum of about 410 MPa tensile and 390 MPa yield, placing it in the same strength class as 7021 and 7129. Metline supplies 7A46 profiles in T6, T651 and T7651 to drawing for buyers who build to GB/T 33910 or need a 7xxx crash alloy, worldwide.
- Alloy
- 7A46 (Al-Zn-Mg-Cu)
- Tempers
- T6, T651, T7651
- Min. strength
- Rm 410 MPa, Rp0.2 390 MPa
- Standard
- GB/T 33910
What is 7A46 aluminium?
In the Chinese designation system, a letter after the first digit (as in 7A46) marks a national alloy that is not registered with the Aluminum Association. 7A46 is one of the 7xxx grades written into GB/T 33910 for vehicle extrusions, intended for bumper beams, sill reinforcements, anti-intrusion beams and other parts sized by yield strength.
Like 7129, 7A46 contains a controlled copper addition (0.10 – 0.40 %) alongside its zinc and magnesium, while chromium is held to 0.06 % or less. Copper increases peak strength and helps stress-corrosion behaviour in aged tempers; the low chromium keeps quench sensitivity down so that hollow sections can be quenched consistently.
Because 7A46 is a national grade, export buyers often ask how it compares with familiar alloys. In strength it sits with 7021-T6 and 7129-T6; in processing it behaves like other high-zinc 7xxx extrusion alloys, needing careful quenching, controlled ageing and attention to residual stress.
7A46 chemical composition
7A46 limits are set in GB/T 3190 and referenced by GB/T 33910. The table shows the published limits we have been able to verify; the full analysis of every element is reported on the mill certificate for each lot.
| Element | Limit (wt %) | Comment |
|---|---|---|
| Zinc (Zn) | Main alloying element | Strengthening with Mg (MgZn2 precipitates) |
| Magnesium (Mg) | Major alloying element | Strengthening with Zn |
| Copper (Cu) | 0.10 – 0.40 | Peak strength and SCC behaviour |
| Chromium (Cr) | ≤ 0.06 | Kept low to limit quench sensitivity |
| Fe, Si, Mn, Ti, others | Per GB/T 3190 | Impurity and grain-refiner limits |
| Aluminium (Al) | Remainder |
Some product listings show 7A46 with about 1 % manganese and no zinc. That cannot be right for a 7xxx alloy, whose defining element is zinc. Always check the certificate against GB/T 3190.
Mechanical properties of 7A46 profiles
Minimum values below are those listed for 7A46 extrusions under GB/T 33910 in the peak-aged condition. Over-aged T7651 trades some strength for better stress-corrosion and exfoliation resistance, so its strength is lower than T6, not higher.
| Temper | Tensile strength | Yield strength (0.2 %) | Elongation | Comment |
|---|---|---|---|---|
| T6 / T651, specified minimum | 410 MPa | 390 MPa | 10 % | Peak strength |
| T7651 | Below T6 values | Below T6 values | Similar or higher | Over-aged for SCC resistance; minimums per agreed specification |
Physical properties (typical for this alloy class)
- Density
- about 2.78 – 2.80 g/cm³
- Modulus of elasticity
- about 70 GPa
- Thermal conductivity
- about 130 – 150 W/m·K
- Coefficient of thermal expansion
- about 23.5 µm/m·°C
T6, T651 and T7651 explained
T651
As T6, with controlled stretching after quenching to relieve residual stresses. Profiles stay straighter during machining and carry lower built-in stress, which also helps SCC resistance.
T7651
Stretched, then over-aged. Strength drops by a margin agreed in the specification, but resistance to stress corrosion and exfoliation improves markedly. Preferred for parts exposed to road salt and sustained stress.
Standards, equivalents and supply range
| Item | Detail |
|---|---|
| Composition standard | GB/T 3190 |
| Product standard | GB/T 33910 (vehicle profiles); GB/T 6892 for general industrial profiles |
| International equivalent | No direct AA, EN or JIS equivalent; 7021 and 7129 are the nearest functional alternatives |
| Shape | Typical outer size | Wall thickness |
|---|---|---|
| Square tube | 10 × 10 to 200 × 200 mm | 1 – 20 mm |
| Round tube | OD 10 – 300 mm | 1 – 30 mm |
| Rectangular tube | 10 × 20 to 200 × 400 mm | 1 – 20 mm |
| T and U profiles | 20 × 20 to 200 × 200 mm (T); to drawing (U) | 1 – 20 mm |
7A46 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.
Joining, forming and protection
Welding
Copper-bearing high-strength 7xxx alloys are sensitive to hot cracking in fusion welding. For structural joints use self-piercing rivets, flow-drill screws, bolts or bonding; if welding is unavoidable, qualify the procedure with 5xxx filler and test joints.
Stress corrosion
Like all Al-Zn-Mg alloys, 7A46 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 7A46 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 applications of 7A46
| Component | Preferred temper | Reason |
|---|---|---|
| Front and rear bumper beams | T6 / T7651 | High yield for bending loads |
| Sill and rocker inserts | T7651 | Side-impact strength with SCC margin |
| Door anti-intrusion beams | T6 / T651 | Compact, high-strength section |
| Battery-pack protection beams | T7651 | Strength plus durability against road salt |
| Seat cross-members and brackets | T651 | Straightness for machining |
7A46 is not a heat-exchanger or engine alloy. Radiators use 3xxx brazing sheet and microchannel tube, and engine parts are cast. Like all peak-aged 7xxx alloys, 7A46 loses strength with prolonged exposure above roughly 120 °C.
7A46 compared with 7021, 7129 and 7003
| Property | 7A46-T6 | 7021-T6 | 7129-T6 | 7003-T5 |
|---|---|---|---|---|
| Yield strength | ≥ 390 MPa (min.) | about 390 MPa (typ.) | about 390 MPa (typ.) | ≥ 260 MPa (min.) |
| Copper | 0.10 – 0.40 % | ≤ 0.25 % | 0.50 – 0.90 % | ≤ 0.20 % |
| Main standard | GB/T 33910 | EN 755-2 | ASTM B221 | EN 755-2 |
| Weldability | Poor – fair | Fair | Poor – fair | Good |
How to order 7A46 profiles
- SpecifyAlloy and temper (7A46-T6, T651 or T7651), drawing, length, quantity and machining.
- Confirm the standardGB/T 33910 or your OEM specification, including minimum properties for T7651 and any SCC tests.
- QuoteWe confirm availability, tolerances, certification and delivery terms (EXW, FOB, CIF or DAP) for your plant or port.
- Process and inspectProfiles are extruded, quenched, stretched, aged, cut and inspected, with tensile tests 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
- GB/T 33910 – Aluminium and aluminium alloy extruded profiles for motor vehicles
- GB/T 3190 – Chemical composition of wrought aluminium and aluminium alloys
- ASTM G47 – Determining Susceptibility to Stress-Corrosion Cracking of 2XXX and 7XXX Aluminum Alloy Products
- EN 573-3 – Aluminium and aluminium alloys: chemical composition and form of wrought products
- IATF 16949 – Quality management system requirements for automotive production and relevant service parts organisations
7A46 automotive aluminium (aluminum) profiles: FAQ
What standard covers 7A46 automotive profiles?
GB/T 33910, the Chinese standard for aluminium extruded profiles for motor vehicles, with composition limits in GB/T 3190.
Is T7651 stronger than T6?
No. T7651 is over-aged, so its strength is lower than T6. It is chosen for better resistance to stress corrosion and exfoliation, not for extra strength.
What is the international equivalent of 7A46?
There is no direct equivalent. In strength and use it is closest to 7021-T6 and 7129-T6.
Can 7A46 be welded?
It is not recommended for structural welds because of hot-cracking risk. Mechanical fastening and bonding are preferred.
Can Metline certify 7A46 to an OEM specification?
Yes. Tell us the specification and test requirements; each lot ships with an EN 10204 3.1 certificate.
Sourcing 7A46 profiles?
Send your drawing, temper and volumes. We will reply with feasibility, certification and a delivered price.
