T6
Solution heat-treated by intensive press quench (usually water) and artificially aged. Standard delivery condition.
GB automotive extrusion alloy
6S02 T6 Automotive Aluminium Extrusions
6S02 is a GB/T 3190 designation for a high-strength, silicon-rich Al-Mg-Si-Cu extrusion alloy aimed at automotive structures. With a guaranteed T6 tensile strength of about 315 MPa and proof strength of 285 MPa, it sits above 6061 and 6082 in strength while keeping good elongation. Metline supplies 6S02-T6 profiles to drawing for vehicle makers and tier suppliers worldwide.
- Alloy
- 6S02 (GB/T 3190)
- Temper
- T6
- Min. strength (T6)
- Rm 315 / Rp0.2 285 MPa
- Standards
- GB/T 33910 · GB/T 3190
What is 6S02 aluminium?
6S02 uses an excess-silicon chemistry: silicon of about 0.9 – 1.15 % against magnesium of 0.5 – 0.7 %, so there is more silicon than needed to form Mg2Si. The surplus silicon and a 0.32 – 0.50 % copper addition raise the ageing response, while manganese and chromium form dispersoids that keep a fine, partly unrecrystallised grain structure. That structure is what gives high strength together with good bending and energy absorption.
Alloys of this type are used for structural profiles in body-in-white, sub-frames, battery enclosures and crash-relevant members, where engineers want T6 proof strength near 300 MPa without the weldability and stress-corrosion concerns of 7xxx alloys.
The designation is specific to the GB system. For global programmes, the closest international comparisons are high-strength crash and structural 6xxx alloys such as 6082 and copper-bearing variants; any substitution must be validated by the part owner, as crash behaviour depends on processing as much as chemistry.
6S02 chemical composition (wt %)
Limits below are those published for 6S02 under GB/T 3190. The tight copper (0.32 – 0.50 %) and chromium (0.10 – 0.30 %) windows are characteristic of the alloy.
| Element | Limit (%) |
|---|---|
| Silicon (Si) | 0.90 – 1.15 |
| Iron (Fe) | 0.30 max |
| Copper (Cu) | 0.32 – 0.50 |
| Manganese (Mn) | 0.15 – 0.40 |
| Magnesium (Mg) | 0.50 – 0.70 |
| Chromium (Cr) | 0.10 – 0.30 |
| Zinc (Zn) | 0.08 max |
| Titanium (Ti) | 0.05 max |
| Others, each | 0.05 max |
| Aluminium (Al) | Remainder |
GB alloy limits can change between editions of GB/T 3190. The mill certificate for each lot shows the actual analysis, and the edition named on your drawing governs.
6S02 mechanical properties
Minimum values are those listed for 6S02-T6 profiles; typical values are indicative and depend on section and quench rate. Crash-relevant parts are often also specified by bending angle or axial crush tests on the drawing.
| Temper | Tensile strength Rm | Proof strength Rp0.2 | Elongation A |
|---|---|---|---|
| T6 (specified minimum) | 315 MPa | 285 MPa | 15 % |
| T6 (typical production) | about 330 – 360 MPa | about 300 – 330 MPa | 12 – 16 % |
Physical properties (typical for this alloy family)
- Density
- about 2.70 g/cm³
- Modulus of elasticity
- about 69 – 70 GPa
- Thermal conductivity
- about 160 – 180 W/m·K in T6
- Coefficient of thermal expansion
- about 23 µm/m·°C
Tempers and heat treatment
Quench sensitivity
Excess-silicon, copper-bearing alloys need fast quenching; section design with even wall thickness helps reach T6 minimums.
Under-aged options
Slightly under-aged tempers can be agreed to improve crush folding at a small cost in strength.
Bend and crush testing
Three-point bend (for example per VDA 238-100) or axial crush tests can be added to the inspection plan.
6S02 profile range
Typical supply range
- Shapes
- Custom open and hollow sections to drawing; round, square and rectangular tube; angle, U, T, Z and H sections
- Round sections
- About 10 – 250 mm diameter, wall roughly 0.5 – 50 mm depending on section
- Rectangular sections
- Typical sizes from about 20 × 10 mm up to 100 × 80 mm and larger custom hollows
- Length
- Mill lengths or cut to drawing, according to vehicle and part
- Finish
- Mill, anodised, e-coat, powder coated or sand-blasted
Tolerances and inspection
Automotive profiles are almost always made to a part drawing, and the drawing tolerances override the general tables. Where the drawing is silent, the general tolerance standard of the order applies. Critical dimensions, such as mating faces, screw bosses and crash-relevant wall thicknesses, should be marked so they can be measured on every lot.
Tolerance and inspection framework
- General dimensional tolerances
- EN 755-9 for EN orders; ASTM B221 with ANSI H35.2 tables for ASTM orders; GB/T 14846 where a GB drawing applies
- Straightness and twist
- Per the same standards, or tighter values agreed for long members and parts that go straight into robotic welding
- Wall thickness
- Measured at drawing-defined points; closed hollow sections are checked for eccentricity and die-line quality
- Mechanical testing
- Tensile test per lot to EN ISO 6892-1 or ASTM B557, with hardness (Webster or Brinell) for in-process checks
- Microstructure
- Grain size and recrystallised surface layer checked on request, which matters for crash and bending performance
- Documentation
- EN 10204 3.1 certificate; PPAP-style first-article dimensional report on request for series parts
Joining, machining and finishing
Like other copper-bearing 6xxx alloys, 6S02 machines cleanly in T6 and can be MIG, TIG, laser or friction-stir welded, with ER4043 or ER5356 filler for arc processes. The heat-affected zone loses a large share of its T6 strength, so crash and load paths are usually designed around mechanical joints, adhesive bonding or welds in low-stress areas. The copper content means painted or anodised finishes are recommended where parts see road salt.
Mill finish
Supplied as extruded and aged, for parts that are welded, bonded or painted later in the body shop or e-coat line.
Anodising
Clear or coloured anodic films for trim, roof rails and visible parts. Film class is specified in micrometres, for example AA15 or AA20 for exterior exposure.
E-coat (electrophoretic paint)
Thin, uniform paint that penetrates hollow sections; often used after anodising for a smooth, durable finish on trim.
Powder coating
Thicker polyester or epoxy layers for chassis brackets, racks and accessories that see stone chipping.
Conversion coating
Chromium-free titanium or zirconium pre-treatment before adhesive bonding or painting, improving bond durability.
Machining and fabrication
Cut-to-length, CNC machining, punching, bending and drilling on request, so profiles arrive ready for assembly.
Where 6S02 profiles are used
- Body-in-white: sills, A/B-pillar reinforcements, roof and floor cross-members
- Crash management: bumper beams and crash boxes where the design calls for a high-strength 6xxx alloy
- EV battery enclosures: side-impact rails and cross-beams
- Sub-frames and chassis: extruded arms and cradle members
- Two-wheelers and light vehicles: frame tubes and structural sections
For decorative trim, door frames or complex thin housings, lower-strength alloys such as 6063, 6463 or 6106 are easier to extrude and finish.
6S02 compared with international alloys
| Property | 6S02-T6 | 6082-T6 | 6061-T6 | 6005A-T6 |
|---|---|---|---|---|
| Min. tensile (thin wall) | 315 MPa | 290 MPa | 260 MPa | 270 MPa |
| Min. proof (thin wall) | 285 MPa | 250 MPa | 240 MPa | 225 MPa |
| Copper | 0.32 – 0.50 % | 0.10 % max | 0.15 – 0.40 % | 0.30 % max |
| Extrudability | Moderate | Moderate | Moderate | Good |
How to order 6S02 profiles
- SpecifyAlloy and temper (6S02-T6), section drawing, lengths, finish and annual volume; tell us whether an international alternative is acceptable.
- Confirm the standardGB/T 33910 and GB/T 3190 for GB orders, or the OEM material specification; ASTM B221 or EN 755 for alternatives.
- QuoteWe confirm availability, tolerances, certification and delivery terms (EXW, FOB, CIF or DAP) for your plant or port.
- Process and inspectProfiles are cut, finished, inspected to drawing and packed for export.
- Document and shipEach lot ships with an EN 10204 3.1 mill test certificate, lot traceability and a packing list, in seaworthy export packing. Third-party inspection can be arranged on request.
References and standards
- GB/T 3190 – Wrought aluminium and aluminium alloys: chemical composition
- GB/T 33910 – Aluminium and aluminium alloy extruded profiles for automobiles
- ASTM B221 – Aluminum and Aluminum-Alloy Extruded Bars, Rods, Wire, Profiles, and Tubes
- EN 755-2 – Extruded rod/bar, tube and profiles: mechanical properties
- IATF 16949 – Quality management system requirements for automotive production and relevant service parts organisations
6S02 automotive aluminium (aluminum) extrusions: frequently asked questions
What kind of alloy is 6S02?
A GB-registered, silicon-rich Al-Mg-Si alloy with copper, manganese and chromium additions, designed for high-strength automotive extrusions.
How strong is 6S02-T6?
Minimum tensile strength is about 315 MPa and minimum proof strength about 285 MPa, with about 15 % elongation.
Is there an international equivalent?
There is no exact AA or EN equivalent. 6082-T6 is the nearest common alternative, though it is somewhat weaker; substitutions must be approved by the part owner.
Can 6S02 be welded?
Yes, by MIG, TIG, laser or friction stir welding, with strength loss in the heat-affected zone as for other 6xxx alloys.
Do you supply 6S02 outside China?
Yes. Metline supplies 6S02 profiles worldwide with certificates and export packing.
Need 6S02 profiles?
Send the section drawing, temper and volume. We will reply with feasibility, certification and delivered pricing.
