7020-T6
Solution heat-treated and artificially aged. Normal for sheet and thin plate used flat or welded.
Weldable high-strength structural plate
7020 Aluminium Plate
7020 (EN AW-7020, AlZn4.5Mg1) is the European weldable 7xxx structural alloy. It is stronger than 6082, it can be fusion-welded where 7075 cannot, and its heat-affected zone regains much of its strength by natural ageing after welding. That makes 7020-T6 and T651 plate a standard choice for rail vehicles, truck and trailer frames, cranes and protective structures. Metline supplies 7020 plate cut to size, with EN certification, worldwide.
- Alloy
- EN AW-7020 (AlZn4.5Mg1)
- Tempers
- T6, T651
- Thickness
- 1 – 200 mm
- Standards
- EN 485 · EN 573-3
What is 7020 aluminium plate?
7020 contains about 4.5 % zinc and 1.2 % magnesium, with chromium and zirconium for grain control, and almost no copper. In the 7xxx family, the copper-free Al-Zn-Mg alloys are the ones that can be fusion-welded without hot cracking and without permanent loss of most of their strength.
The metallurgical reason is the natural ageing behaviour of Al-Zn-Mg. Welding heat dissolves the strengthening precipitates near the weld, but because the alloy is not very quench-sensitive, the heat-affected zone cools fast enough to keep zinc and magnesium in solution. Over the following weeks at room temperature, fine precipitates re-form and the zone regains a substantial part of its original strength. 6xxx alloys such as 6082 do not recover in this way.
Designers therefore use 7020 where a welded structure must be lighter than 6082 allows: rail car underframes, bogie parts, crane booms, military vehicle structures and heavy trailer chassis. The alloy is also used unwelded, as machined plate, where a little more strength than 6082 is needed without the corrosion sensitivity and cost of 7075.
7020 chemical composition (wt %)
Limits per EN 573-3. The mill certificate for every lot reports the measured analysis.
| Element | Minimum | Maximum | Role |
|---|---|---|---|
| Zinc (Zn) | 4.0 | 5.0 | With Mg, forms the strengthening MgZn2-type precipitates |
| Magnesium (Mg) | 1.0 | 1.4 | Strengthening partner to zinc |
| Manganese (Mn) | 0.05 | 0.50 | Grain control |
| Chromium (Cr) | 0.10 | 0.35 | Resistance to stress corrosion; grain control |
| Zirconium (Zr) | 0.08 | 0.20 | Inhibits recrystallisation; improves weld-zone toughness |
| Zr + Ti | 0.08 | 0.25 | Grain refinement |
| Silicon (Si) | — | 0.35 | Impurity |
| Iron (Fe) | — | 0.40 | Impurity |
| Copper (Cu) | — | 0.20 | Kept low to preserve weldability |
| Others, each / total | — | 0.05 / 0.15 | |
| Aluminium (Al) | Remainder |
7020 mechanical properties
The table shows minimum values commonly published for EN 485-2 T6/T651 plate. As with all heat-treated plate, minimums fall with thickness. Typical results in plate up to about 40 mm are around 370 – 380 MPa tensile and 310 – 320 MPa proof stress.
| Temper | Thickness | Tensile Rm (min) | Proof Rp0.2 (min) | Elongation (min) |
|---|---|---|---|---|
| T6 | 0.4 – 6 mm (sheet) | 350 MPa | 280 MPa | 7 – 10 % |
| T651 | 6 – 40 mm | 350 MPa | 280 MPa | 9 – 10 % |
| T651 | 40 – 100 mm | 340 MPa | 270 MPa | 8 % |
| T651 | 100 – 150 mm | 330 MPa | 260 MPa | 7 % |
| T651 | 150 – 175 mm | 330 MPa | 260 MPa | 6 % |
Thickness bands and limits follow the EN 485-2 edition named on the order; confirm them against the certificate.
Physical properties (typical)
- Density
- 2.78 g/cm³
- Modulus of elasticity
- about 70 GPa
- Thermal conductivity
- about 130 – 160 W/m·K, depending on temper
- Electrical conductivity
- about 19 – 23 MS/m (33 – 40 % IACS)
- Coefficient of thermal expansion
- about 23.1 µm/m·°C (20 – 100 °C)
- Specific heat
- about 875 J/kg·K
- Melting range
- about 600 – 650 °C
7020-T6 vs 7020-T651
7020-T651
As T6, plus stretching after quenching to relieve residual stress. Standard for plate that will be machined, cut into large blanks or welded into precise assemblies.
After welding
The heat-affected zone recovers by natural ageing over roughly 30 – 90 days. A post-weld artificial ageing cycle can speed this up where the structure allows it.
7020 standards and equivalents
| System | Designation | Note |
|---|---|---|
| European (EN) | EN AW-7020 / EN AW-AlZn4.5Mg1 | Plate to EN 485-1/-2/-3/-4; chemistry to EN 573-3 |
| German Werkstoff | 3.4335 (AlZn4.5Mg1) | Former DIN designation |
| ISO | AlZn4.5Mg1 | ISO 209 |
| British (former) | H17 | Superseded by EN |
| Aluminum Association | 7020 | Registered international alloy |
| China (GB) | 7020 | GB/T 3190 |
Welded rail vehicle structures are usually fabricated under EN 15085, and structural design follows EN 1999 (Eurocode 9) with HAZ strength reductions for 7020 given in the code.
7020 plate sizes and weights
Supply range
- Thickness
- 1 – 6 mm sheet; 6 – 200 mm plate
- Width
- 1000 – 2500 mm
- Length
- 2000 – 8000 mm and cut-to-size
- Common sizes
- 1250 × 2500, 1500 × 3000, 1520 × 3020, 1525 × 3660 mm
- Surface protection
- PE film on one or both faces, paper interleaving
- Cut tolerance
- Saw-cut blanks typically ±1 – 2 mm on length and width; tighter on request
7020 weighs 2.78 kg per m² per millimetre, about 3 % heavier than 6082 at the same thickness, which is easily outweighed by the thinner sections its strength allows.
| Thickness (mm) | kg per m² | 1250 × 2500 mm (kg) | 1500 × 3000 mm (kg) |
|---|---|---|---|
| 2 | 5.56 | 17.4 | 25.0 |
| 3 | 8.34 | 26.1 | 37.5 |
| 4 | 11.12 | 34.8 | 50.0 |
| 5 | 13.90 | 43.4 | 62.5 |
| 6 | 16.68 | 52.1 | 75.1 |
| 8 | 22.24 | 69.5 | 100.1 |
| 10 | 27.80 | 86.9 | 125.1 |
| 12 | 33.36 | 104.2 | 150.1 |
| 15 | 41.70 | 130.3 | 187.6 |
| 20 | 55.60 | 173.7 | 250.2 |
| 25 | 69.50 | 217.2 | 312.8 |
| 30 | 83.40 | 260.6 | 375.3 |
| 40 | 111.20 | 347.5 | 500.4 |
| 50 | 139.00 | 434.4 | 625.5 |
| 60 | 166.80 | 521.2 | 750.6 |
| 80 | 222.40 | 695.0 | 1000.8 |
| 100 | 278.00 | 868.8 | 1251.0 |
Welding, machining and surface treatment
Welding
MIG and TIG with 5356, 5183 or 5556 filler. Avoid 4xxx fillers, which give weak, brittle welds in Al-Zn-Mg. Clean oxide and degrease thoroughly; keep heat input moderate to limit the width of the softened zone.
Weld design
Place welds away from the highest stresses, avoid welds that leave sustained tensile stress across the short-transverse direction, and remove sharp notches at weld toes to support fatigue life.
Stress corrosion
Al-Zn-Mg alloys can be sensitive to stress corrosion cracking in weld zones with high residual stress. Correct filler choice, joint design and, where required, post-weld ageing or peening reduce the risk.
Machining
Good machinability, with crisp chips. T651 limits distortion; for very large pockets, rough machine, rest, then finish.
Cutting
Saw, waterjet and plasma cutting are all used. Plasma leaves a heat-affected edge that is usually machined back.
Surface treatment
Anodising, painting and powder coating give good protection. Zinc content can give a slightly uneven anodised colour, so it suits protective rather than decorative finishes.
Typical applications of 7020 plate
Rail vehicles
Underframes, bogie components, brackets and welded body sections where 7020 saves weight over 6082 while staying weldable.
Trucks and trailers
Chassis members, tipper bodies and special-vehicle frames that must carry high payloads.
Protective structures
Military vehicle hulls, crash structures and protective panels; projects normally specify their own test and certification requirements.
Lifting equipment
Crane booms, access-platform arms and lifting beams, where lighter structures increase reach and payload.
Bridges and platforms
Portable bridges, industrial platforms and support frames assembled by welding.
Sport and frames
Bicycle components and lightweight frames, usually from 7020 tube and plate together.
A typical example: a rail car builder replacing 6082-T6 floor members with 7020-T651 can reduce plate thickness by around 15 % for the same proof stress, while keeping the same welding procedure family with 5xxx filler.
7020 compared with 6082, 7005 and 7075
| Property | 6082-T651 | 7020-T651 | 7005-T6 | 7075-T651 |
|---|---|---|---|---|
| Typical tensile strength | 330 – 340 MPa | 370 – 380 MPa | about 350 MPa | 570 MPa |
| Typical proof strength | 300 – 310 MPa | 310 – 320 MPa | about 290 MPa | 505 MPa |
| Fusion weldability | Good | Good | Good | Poor |
| HAZ recovery | Little | Good (natural ageing) | Good (natural ageing) | Not welded |
| Typical use | General structures | High-strength welded structures | Extruded frames, tube | Machined high-strength parts |
For general structures, 6082 or 6061 is usually sufficient. For unwelded parts that need very high strength, choose 7075. Where a welded, load-bearing structure must be as light as possible, 7020 is usually the first alloy to evaluate.
How to order 7020 plate
- SpecifyAlloy and temper (for example 7020-T651, 25 × 1500 × 3000 mm), thickness, width and length or a drawing, quantity, and the governing standard (EN 485 / EN 573-3 or your drawing).
- QuoteWe confirm availability, tolerances, certification and delivery terms (EXW, FOB, CIF or DAP) for your destination.
- ProcessPlate is saw-cut or waterjet-cut to size where required, film-protected on request and inspected for dimensions and surface.
- DocumentEach shipment carries a mill test certificate to EN 10204 3.1 with chemistry and mechanical results, plus the packing list; third-party inspection can be arranged.
- ShipSeaworthy wooden cases or fumigated pallets, dispatched by sea or air to your port or door.
For a fast quote, include the welding process you plan to use and any rail, defence or class requirements, so we can confirm the right temper and documentation. Pallet weight, protective film, neutral marking and export documents (commercial invoice, packing list, certificate of origin) are arranged to your requirements.
References and standards
- EN 485-2 – Aluminium and aluminium alloys: sheet, strip and plate, mechanical properties
- EN 573-3 – Chemical composition and form of wrought products
- EN 1999-1-1 (Eurocode 9) – Design of aluminium structures
- EN 15085 – Railway applications: welding of railway vehicles and components
- The Aluminum Association – International Alloy Designations and Chemical Composition Limits
7020 aluminium (aluminum) plate: FAQ
What is 7020 aluminium plate?
A weldable high-strength Al-Zn-Mg plate, designated EN AW-7020 / AlZn4.5Mg1 / 3.4335, used for welded and machined structures in rail, vehicle, lifting and defence applications.
Can 7020 be welded?
Yes. It is one of the weldable 7xxx alloys. Use 5xxx filler such as 5356 or 5183. The heat-affected zone recovers much of its strength through natural ageing after welding.
Is 7020 stronger than 6082?
Yes. 7020-T651 has a minimum proof stress of about 280 MPa in plate up to 40 mm, against 240 – 255 MPa for 6082-T651.
7020 or 7075 for a welded structure?
7020. 7075 is far stronger but is not suitable for fusion welding, while 7020 is designed to be welded.
What is the difference between 7020-T6 and T651?
Both are solution treated and artificially aged. T651 is also stretched to relieve residual stress, so it distorts less when machined.
Can 7020 be anodised?
Yes, for protection. Because of its zinc content the colour may be uneven, so it is better for protective than decorative finishes.
What affects the price of 7020 plate?
The aluminium price, thickness, plate size, temper, tolerances, cutting, quantity, packing and delivery terms.
Need 7020 plate for a welded structure?
Send the temper, size, quantity, welding process and destination. We will confirm availability, documents and a delivered price.
