7003-T6 Aluminum
A 7000-series Al-Zn-Mg-Zr alloy, for welded extrusions
Typical values for the temper in the title
7003 is a zinc-magnesium alloy with zirconium and almost no copper, intended for extrusion and welding. In T6 its tensile strength is 380–400 MPa.
It is used for welded extrusions in vehicles, rail and bicycle frames, where more strength than the 6000 series is needed while still welding.
Mechanical and physical properties
| Property | Value | Note |
|---|---|---|
| Tensile strength Rm | 380–400 MPa | |
| Yield strength Rp0.2 | 340–360 MPa | |
| Elongation A | 13% | |
| Hardness | 100 HB | |
| Modulus of elasticity E | 71.7 GPa | |
| Density ρ | 2.78 g/cm³ | |
| Machinability | 65% | relative rating in the site database |
Chemical composition (wt %)
| Element | Range | Role |
|---|---|---|
| Zn zinc | 5.0–6.5 | strengthening |
| Mg magnesium | 0.5–1.0 | strengthening |
| Zr zirconium | 0.05–0.25 | controls the grains |
| Fe iron | max 0.35 | |
| Si silicon | max 0.30 | |
| Mn manganese | max 0.30 | |
| Cr chromium | max 0.20 | |
| Ti titanium | max 0.20 | |
| Cu copper | max 0.20 | |
| Al aluminum | balance |
Common tempers
7003 is supplied mostly as extrusions in the T5 and T6 tempers.
| Temper | Properties | When to choose it |
|---|---|---|
| T5 | slightly lower strength | cooled from extrusion and aged |
| T6 | Rm 380–400 MPa | maximum strength |
Applications
- Welded extrusions in vehicles
- Rail structures
- Bicycle frames
- Welded structures of medium-high strength
- Structural tubes and profiles
Fabrication
Welding
Welds well, usually with ER5356 filler, and the heat-affected zone regains strength by natural aging.
Extrusion
Extrudes well into profiles.
Corrosion
More susceptible than the 6000 series to stress corrosion cracking. Controlled welding and heat-treatment procedures matter.
Compared with similar materials
| Material | Rm / Rp0.2 | Welding | When it is the better choice |
|---|---|---|---|
| 7005-T6 | 350 / 290 MPa | Excellent — ER5356 | another weldable 7000-series alloy · material page |
| 7020-T651 | 350 / 280 MPa | Excellent — ER5356 | a European counterpart for plate and extrusions · material page |
| 6082-T6 | 310 / 260 MPa | Good — ER4043 | more available and more corrosion resistant, at lower strength · material page |
Common mistakes
Testing a welded structure right after welding
Strength in the weld zone keeps rising for weeks.
Ignoring stress corrosion susceptibility
Controlled welding and heat-treatment procedures are needed.
Replacing 7003 with 7075 to gain strength
7075 does not weld.
Equivalents, standards and supply
| EN | EN AW-7003 (AlZn6Mg0.8Zr) |
|---|---|
| Standards | EN 755-2 |
| Forms | extrusion profile |
| Producers | Hydro · Constellium |
Learn more
Values are typical and for comparison only. For design, rely on the standard and on the mill certificate. Sources: Aluminum Association (composition), ASM and MatWeb data sheets, and the METAL HUB materials database.
Updated: October 31, 2026