Stamping
Aluminium has lower formability limits and higher springback than mild steel. Generous radii, optimised draw beads and simulation with the actual 6A16 forming-limit curve keep splits and wrinkles under control.
Automotive body sheet
6A16 T4Pa / T6Bb Automotive Body Sheet
6A16 is a GB/T 3190 body sheet alloy of the 6016 type, listed in GB/T 33227 for automotive sheet and strip. Supplied in pre-aged T4P (often coded T4Pa), it stamps and hems well and gains strength in the paint bake (tested in the T6B or T6Bb condition). Metline supplies 6A16 sheet and coil in standard and high bake-response grades to vehicle makers and stampers worldwide.
- Alloy
- 6A16 (GB/T 3190)
- Tempers
- T4P / T4Pa
- Thickness
- About 0.7 – 1.5 mm
- Standards
- GB/T 33227 · GB/T 3190
What is 6A16 body sheet?
6A16 is a national variant of the 6016 family, registered in GB/T 3190 and used in the Chinese automotive sheet standard GB/T 33227. Like 6016, it relies on silicon and magnesium for age hardening, with copper held low (0.02 – 0.20 %) for corrosion resistance. Its composition windows are adapted to local scrap and processing routes and to the bake cycles used in many paint shops.
The alloy is normally sold in two strength grades: a standard (S) grade for general outer and inner panels, and an improved bake-response (IBR) grade that develops more strength in the paint oven for better dent resistance. Both are delivered in a pre-aged T4P condition, often written T4Pa, to stabilise properties during storage.
For programmes outside China, 6016 (EN AW-6016) is the closest international alloy, and many drawings list both. We can supply either and certify to the standard named on the drawing.
6A16 chemical composition (wt %)
Limits below are those published for 6A16 under GB/T 3190. The copper, iron and chromium limits are widely cited; confirm the full table against the edition named on your drawing, and check the lot certificate for the actual analysis.
| Element | 6A16 (wt %) |
|---|---|
| Silicon (Si) | 0.6 – 1.2 |
| Iron (Fe) | 0.40 max |
| Copper (Cu) | 0.02 – 0.20 |
| Manganese (Mn) | 0.01 – 0.25 |
| Magnesium (Mg) | 0.7 – 1.3 |
| Chromium (Cr) | 0.10 max |
| Zinc (Zn) | 0.25 – 0.8 |
| Titanium (Ti) | 0.15 max |
| Others, each / total | 0.05 / 0.15 |
| Aluminium (Al) | Remainder |
6A16 mechanical properties
Properties below are typical specification values for 6A16 T4P body sheet, 0.70 – 1.50 mm thick, as used in GB/T 33227-style purchase specifications. The bake test is 2 % pre-strain and a laboratory bake cycle stated in the order.
| Property | Standard grade (S) | Improved bake response (IBR) |
|---|---|---|
| Tensile strength Rm, T4P | ≥ 220 MPa | ≥ 230 MPa |
| Proof strength Rp0.2, T4P | 100 – 150 MPa | 110 – 150 MPa |
| Elongation A50, T4P | ≥ 24 % | ≥ 24 % |
| Strain-hardening exponent n (10 – 20 %) | ≥ 0.24 | ≥ 0.24 |
| Plastic strain ratio r (10 %) | ≥ 0.5 | ≥ 0.5 |
| Proof strength after pre-strain and bake (T6B) | 220 – 280 MPa | 240 – 300 MPa |
Physical properties (typical)
- Density
- 2.70 g/cm³
- Modulus of elasticity
- about 70 GPa
- Thermal conductivity
- about 170 – 190 W/m·K
Additional requirements often called up for body panels include flat-hem grade, paint-brush line (roping) grade, dent resistance, forming-limit curve and high-strain-rate tensile data; specify which ones you need reported.
T4, T4P and the paint-bake response
6xxx body sheet is delivered soft enough to stamp and gains most of its in-service strength in the paint shop. After the body is e-coated, the bake oven (typically 170 – 190 °C for 20 – 30 minutes) acts as an artificial ageing treatment: fine Mg-Si precipitates form and the yield strength of the panel rises. Strain from stamping adds a further work-hardening increment. This is the bake-hardening or paint-bake response, and it is why a door skin can be pressed easily yet resist dents on the road.
| Condition | What it means | Why it matters for 6A16 |
|---|---|---|
| T4 | Solution heat-treated and naturally aged at room temperature | Natural ageing continues for weeks; formability slowly falls and bake response weakens |
| T4P (T4 pre-aged) | Solution treated, then given a short pre-ageing treatment (roughly 70 – 100 °C) immediately after quenching | Stabilises properties during storage and gives a stronger, faster bake response |
| T6B / T8X test state | T4P sheet pre-strained about 2 % and baked in the laboratory (for example 185 °C for 20 minutes) | Simulates the painted panel; used to verify dent resistance |
| T6 | Fully artificially aged to peak strength | For structural parts that need maximum strength and little forming |
Suffix letters such as T4Pa or T6Bb are supplier or OEM sub-codes for a specific pre-ageing or bake cycle. Always state the cycle and test method in the order.
Surface texture, pre-treatment and lubricant
Body sheet is ordered not just by alloy and temper but by surface texture, pre-treatment and lubricant, because these decide how the coil behaves in the press shop, the adhesive line and the paint shop. The codes below are the ones most purchase specifications use; your OEM specification may use its own names for the same options.
| Option | Code | What it does | Where it is used |
|---|---|---|---|
| Mill finish | MF | Roll-ground surface straight from cold rolling, with a fine directional pattern | Inner panels and structural parts |
| Electro-discharge textured | EDT | Surface printed from work rolls textured by spark erosion; a random, isotropic micro-pattern holds lubricant and gives an even paint appearance | Visible outer panels: bonnets, doors, roofs, tailgates |
| Ti/Zr conversion pre-treatment | P / TiZr | Thin titanium-zirconium conversion layer applied on the finishing line; stabilises the oxide for durable adhesive bonding | Bonded and riveted body structures |
| Cleaned only | NP | Degreased and pickled surface, no pre-treatment film | Parts pre-treated by the customer |
| Dry lubricant (hot-melt) | DO | Wax-type lubricant that is solid at room temperature; clean handling and good deep-drawing performance | Complex outer panels and automated lines |
| Wet oil (electrostatic) | EO | Thin, even film of forming oil laid down electrostatically, typically about 0.5 – 1.5 g/m² per side | General stamping |
Lubricant type and coating weight must be compatible with your adhesives, sealers and pre-treatment chemistry. Confirm both with the paint shop before the first trial coil of 6A16.
6A16 sheet and coil sizes and tolerances
Typical supply range
- Thickness
- About 0.7 – 1.5 mm for closures and outer panels; up to about 3 – 4 mm for structural parts
- Width
- About 800 – 2400 mm
- Form
- Coil (for blanking lines) or cut sheet and blanks, typically 800 – 5500 mm long
- Tempers
- T4, T4P; T6 on request for structural parts
- Standards
- EN 485 / EN 573-3, ASTM B209, GB/T 33227, JIS H4000, or the OEM specification
Body sheet tolerances are tighter than general-purpose sheet because blanks feed automated presses and lasers. The schedule below is typical for cut sheet and coil in the 0.7 – 1.5 mm range used for closures; the governing figures are those of your order standard (EN 485-4, ASTM B209 or GB/T 33227) or the OEM specification, whichever is tighter.
| Thickness (mm) | Width 800 – 1600 mm | Width 1600 – 1800 mm | Width 1800 – 2400 mm |
|---|---|---|---|
| 0.70 – 1.00 | ±0.03 | ±0.05 | ±0.08 |
| 1.00 – 1.20 | ±0.04 | ±0.06 | ±0.09 |
| 1.20 – 1.50 | ±0.05 | ±0.07 | ±0.10 |
Other dimensional and quality checks
- Width and length
- Plus-only tolerances on slit width and cut length, typically a few millimetres on blanks over 2 m
- Squareness
- Diagonal difference controlled so that blanks register correctly in the press
- Flatness
- Measured as wave height per metre; outer-panel sheet is levelled to avoid surface distortion after stamping
- Surface
- No cuts, roll marks or pick-up on the exposed face of outer-panel sheet; minor cosmetic marks allowed on inner and structural grades
- Paint-brush lines (roping)
- Graded by stretching and stoning a sample; outer panels need the best grade
- Hemming
- Flat-hem test graded on cracking at the bend, usually after pre-straining and ageing
Stamping, hemming and joining 6A16
Hemming
Outer panels are hemmed around inner panels at doors, bonnets and tailgates. Good flat-hem performance depends on low iron-particle content and a fine grain; roller hemming is common for tight radii.
Joining
Bodies are joined by self-piercing rivets, clinching, adhesive bonding, resistance spot welding with special electrodes, laser and friction stir welding. Ti/Zr pre-treated surfaces give the most durable adhesive joints.
Shelf life
T4-type sheet ages at room temperature. Use coils within the shelf life agreed with the supplier, and store them cool and dry.
Corrosion
With phosphate or zirconium pre-treatment and e-coat, 6xxx panels perform well. Copper-bearing alloys need good coating integrity to avoid filiform corrosion at edges.
Recycling
Press-shop offcuts are segregated by alloy and returned for closed-loop recycling into new body sheet.
Because 6A16 is used mainly for visible panels, surface protection during slitting, blanking and transport is as important as mechanical properties: specify interleaving or protective film for EDT outer-panel coils if blanks are stored before stamping.
Where 6A16 sheet is used
- Outer closures: bonnets, doors, boot lids and tailgates
- Roof panels and wings
- Inner panels: door and bonnet inners with deep draws
- Body structural parts: reinforcements where moderate strength is enough
- EV and commercial vehicles: battery covers, cab and box panels
6A16 compared with other body sheet alloys
| Property | 6A16 | 6016 | 6181 | 6111 |
|---|---|---|---|---|
| Copper | 0.02 – 0.20 % | 0.20 % max | 0.10 % max | 0.50 – 0.9 % |
| T4P proof strength (typical spec) | 100 – 150 MPa | about 80 – 140 MPa | about 115 – 170 MPa | about 140 – 180 MPa |
| Hemming | Excellent | Excellent | Very good | Good |
| Standards system | GB | EN / AA | EN / AA | AA |
6A16 and 6016 are close substitutes for outer panels; 6181 or 6111 are the choices when higher post-bake strength is needed.
How to order 6A16 body sheet
- SpecifyAlloy and temper (e.g. 6A16-T4P), outer, inner or structural grade, surface (MF/EDT, Ti/Zr), lubricant and weight, thickness, width, coil ID/OD or blank size, and annual volume.
- Confirm the standardYour OEM material specification, or EN 485 / ASTM B209 / GB/T 33227, with the bake-test cycle and formability tests to be reported.
- QuoteWe confirm availability, tolerances, certification and delivery terms (EXW, FOB, CIF or DAP) for your plant or port.
- Process and inspectCoils are slit or blanked, checked for dimensions, surface and properties, and packed eye-to-sky or eye-to-wall in sealed, desiccated export cases.
- 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 33227 – Aluminium and aluminium alloy sheet and strip for automobiles
- EN 573-3 – Aluminium and aluminium alloys: chemical composition and form of wrought products
- EN 485-2 – Sheet, strip and plate: mechanical properties
- The Aluminum Association – International Alloy Designations and Chemical Composition Limits (Teal Sheets)
6A16 automotive body sheet (aluminum): frequently asked questions
What do T4Pa and T6Bb mean?
T4Pa is a supplier or OEM code for a specific pre-aged T4P condition. T6Bb denotes the same material after a defined pre-strain and paint-bake simulation, used to check final strength.
Is 6A16 equivalent to 6016?
It is a 6016-type alloy and performs similarly, but its composition windows differ. Use the alloy named on the drawing, or get approval for substitution.
What is the difference between the S and IBR grades?
The IBR (improved bake response) grade gains more strength in the paint bake, reaching about 240 – 300 MPa proof strength after the test cycle, against 220 – 280 MPa for the standard grade.
What thickness range is used for body panels?
Typically 0.7 – 1.5 mm, with outer panels usually 0.9 – 1.2 mm.
Which surface should I order for outer panels?
EDT texture with Ti/Zr pre-treatment and dry lubricant is common for visible outer panels; mill finish suits inner and structural parts.
Do you supply 6A16 worldwide?
Yes. Metline supplies 6A16 and 6016 sheet and coil worldwide with mill certificates and sealed export packing.
Need 6A16 body sheet?
Send the grade, surface, size and volume. We will reply with availability, certification and delivered pricing.
