Overaged, stretched (T7x511-type)
The normal aerospace condition: high strength with good resistance to stress-corrosion cracking and exfoliation.
Aerospace extrusions
7014 Aerospace Aluminium Extrusions
7014 extrusions are high-strength Al-Zn-Mg-Mn-Cu bars and sections specified on UK and legacy aircraft drawings, heat-treated to an overaged condition for strength with stress-corrosion resistance. They are used for stringers, frames, seat tracks and machined fittings in existing designs. Metline sources 7014 sections to the drawing and specification, or supplies approved alternatives such as 7075-T73511 and 7050-T76511, certified and shipped worldwide.
- Alloy
- 7014 (Zn 5.7, Mg 2.7, Mn 0.5, Cu 0.5)
- Forms
- Bars, angles, T, Z and channel sections
- Condition
- Solution treated, stretched, overaged
- Specification
- Legacy UK / purchaser specs
What are 7014 extrusions?
7014 is a British 7xxx aerospace alloy. Its relatively high magnesium (about 2.7 %) and moderate zinc (about 5.7 %) give high strength, while manganese controls grain structure and copper supports stress-corrosion resistance.
Extruded 7014 bars and sections are solution heat-treated, quenched, stretched to relieve stress and straighten (the "511" suffix in temper designations), and aged. For aerospace structure they are normally taken to an overaged condition, which protects against stress-corrosion cracking where sections are loaded across the grain, for example at fastener holes in stringers and frame flanges.
Extruded sections in 7014 belong mainly to legacy UK airframes. For new structures, designers usually choose 7075, 7050, 7150 or 7175 extrusions, which have SAE AMS specifications and broad mill availability. Metline supports both routes: sourcing 7014 where the drawing requires it, and supplying certified alternatives where the design authority approves them.
7014 chemical composition (wt %)
7014 is defined by British aerospace specifications rather than by a widely published international data sheet. Its nominal composition, given in the titles of BS L 171 and BS L 172, is Zn 5.7 – Mg 2.7 – Mn 0.5 – Cu 0.5. The ranges below are the indicative limits most often quoted for the alloy; the governing values are those of the specification and revision on your order, and every lot is certified against it.
| Element | Nominal | Indicative range | Role |
|---|---|---|---|
| Zinc (Zn) | 5.7 | 5.2 – 6.2 | Main strengthening element with Mg |
| Magnesium (Mg) | 2.7 | 2.2 – 3.2 | Forms MgZn2; high Mg gives strength at modest Zn |
| Manganese (Mn) | 0.5 | 0.3 – 0.7 | Grain control in place of chromium |
| Copper (Cu) | 0.5 | 0.3 – 0.7 | Improves stress-corrosion resistance and strength |
| Silicon (Si) | — | ≤ 0.50 | Impurity |
| Iron (Fe) | — | ≤ 0.50 | Impurity |
| Titanium + zirconium | — | ≤ 0.20 | Grain refinement |
| Aluminium (Al) | Remainder |
Tempers and properties
Property limits for extruded 7014 are set by the governing specification for each section thickness and are reported on the certificate. An earlier version of this page gave about 510 MPa tensile strength and 10 % elongation for T6 and T4 sections, with T4 almost as strong as T6. Those figures could not be confirmed and are not repeated here.
Peak-aged (T6 / T6511)
Maximum strength, but low short-transverse SCC resistance. Used only where the drawing calls for it.
As-extruded or annealed (F / O)
Stock for forging, forming or customer heat treatment.
Physical properties (indicative)
- Density
- ≈ 2.78 – 2.80 g/cm³
- Modulus of elasticity
- ≈ 70 – 72 GPa
- Thermal expansion
- ≈ 23 µm/m·°C
Shapes and sizes
| Shape | Typical use |
|---|---|
| Round, square and rectangular bar | Machined fittings, forging stock |
| Angles and T-sections | Stringers, stiffeners, frame flanges |
| Z and J sections | Fuselage stringers and frame caps |
| Channels and I-sections | Floor beams, seat tracks, spar caps |
| Custom profiles | To drawing, subject to die availability |
Section size, wall thickness and length are confirmed per drawing, since they depend on the die, the press and the specification.
Specifications
| Specification | Scope |
|---|---|
| BS L 171 | Forgings of Al-Zn-Mg-Mn-Cu alloy 7014, up to 150 mm diameter or minor section, supplied as-forged or annealed for use solution treated and overaged |
| BS L 172 | Extruded, rolled or cast forging stock for forgings to BS L 171 |
| UK DTD specifications | Legacy Ministry of Defence material specifications for 7014 bar, section, forgings and plate; still cited on older drawings |
| Purchaser / OEM specifications | Many 7014 orders are placed against the airframe or engine maker's own material specification |
Inspection
- Chemical analysis per cast
- Tensile tests per lot in the longitudinal direction, plus transverse where specified
- Electrical conductivity and hardness to confirm temper
- Dimensional, straightness and twist checks against the section drawing
- Ultrasonic inspection of thick bar and sections when required
- EN 10204 3.1 certificate
Alternatives to 7014 extrusions
| Alloy and temper | Why it is considered |
|---|---|
| 7075-T73511 / T76511 | Widely available, good SCC (T73511) or exfoliation (T76511) resistance |
| 7050-T76511 / T74511 | Higher strength and lower quench sensitivity for thicker sections |
| 7150-T77511 | High compressive strength for upper-wing stringers |
| 7175-T74511 | High toughness and SCC resistance |
Substitution always requires design authority approval, and some sections may need new dies.
How to order 7014 extrusions
- SpecifySection drawing or standard, specification and revision, condition, length and quantity.
- ReviewWe confirm die, sourcing, certification and delivery terms (EXW, FOB, CIF or DAP), or propose an alternative.
- ShipInterleaved and crated for export with the EN 10204 3.1 certificate.
References and standards
- BS L 172 – Extruded, rolled or cast forging stock of Al-Zn-Mg-Mn-Cu alloy (7014)
- ASTM B221 – Aluminum and Aluminum-Alloy Extruded Bars, Rods, Wire, Profiles and Tubes
- ANSI H35.1 – American National Standard Alloy and Temper Designation Systems for Aluminum
- The Aluminum Association – International Alloy Designations and Chemical Composition Limits (Teal Sheets)
7014 aerospace extrusions: frequently asked questions
What does the 511 in an extrusion temper mean?
The section was stretched after quenching to relieve stress, with minor straightening allowed afterwards. It keeps residual stress and distortion low during machining.
Why are 7014 sections overaged?
To improve resistance to stress-corrosion cracking and exfoliation, which matter at fastener holes and flanges loaded across the grain.
Can you make a custom 7014 section?
Yes, subject to die availability and quantity. Send the drawing so we can review it.
What replaces 7014 extrusions in new designs?
7075, 7050, 7150 and 7175 extrusions to SAE AMS specifications are normally used.
Need 7014 sections?
Send the section drawing, specification and quantity. We will confirm sourcing, certification and a delivered price.
