7050-T7451 Aluminum
A 7000-series Al-Zn-Mg-Cu alloy, for thick aerospace parts
Typical values for the temper in the title
7050 was developed as an improvement on 7075 for thick sections. Instead of chromium it contains zirconium, which is less sensitive to the cooling rate in heat treatment. So even at the center of a thick plate it reaches high strength; in T7451 the tensile strength is 496–531 MPa.
In addition, its usual tempers (T74 and T76) are overaged, giving much better stress corrosion resistance and higher toughness than 7075-T6. It is the alloy of fuselage frames, bulkheads and wing panels.
Mechanical and physical properties
| Property | Value | Note |
|---|---|---|
| Tensile strength Rm | 496–531 MPa | |
| Yield strength Rp0.2 | 434–469 MPa | |
| Elongation A | 11% | |
| Hardness | 143 HB | |
| Modulus of elasticity E | 71 GPa | |
| Density ρ | 2.83 g/cm³ | |
| Machinability | 60% | relative rating in the site database |
Chemical composition (wt %)
| Element | Range | Role |
|---|---|---|
| Zn zinc | 5.7–6.7 | forms the strengthening precipitates with magnesium |
| Cu copper | 2.0–2.6 | adds strength and improves stress corrosion resistance |
| Mg magnesium | 1.9–2.6 | part of the strengthening precipitates |
| Zr zirconium | 0.08–0.15 | controls the grains and reduces quench sensitivity |
| Fe iron | max 0.15 | |
| Si silicon | max 0.12 | |
| Mn manganese | max 0.10 | |
| Ti titanium | max 0.06 | |
| Cr chromium | max 0.04 | |
| Al aluminum | balance |
Common tempers
T6 is rarely used for 7050. The overaged tempers are the reason to choose it.
| Temper | Properties | When to choose it |
|---|---|---|
| T7451 | Rm 496–531 MPa, Rp0.2 434–469 MPa | overaged and stress relieved: the common thick-plate temper |
| T7651 | slightly higher strength | good exfoliation resistance, moderate stress corrosion resistance |
| T74 | overaged | forgings |
Applications
- Fuselage frames and bulkheads
- Wing panels and primary structure
- Parts machined from thick plate (50–150 mm)
- Military aircraft structures
- Aerospace forgings
Fabrication
Machining
Machines well, and the T7451 temper (stress relieved) allows large amounts of material to be removed from thick plate without significant distortion.
Welding
Fusion welding is not recommended: the alloy is prone to hot cracking, and the heat-affected zone weakens.
Corrosion and protection
More resistant to stress corrosion cracking than 7075-T6, but it still needs protection: conversion coating, anodizing and paint.
Compared with similar materials
| Material | Rm / Rp0.2 | Welding | When it is the better choice |
|---|---|---|---|
| 7075-T6 | 503–572 / 434–503 MPa | Not recommended — FSW | for thin parts, where thickness does not limit strength · material page |
| 2024-T4 | 470–480 / 325–345 MPa | Not recommended — Hot Cracking | for fatigue-loaded parts such as fuselage skin · material page |
| 7068-T6511 | 710 / 683 MPa | Not recommended | when maximum strength in bar is needed · material page |
Common mistakes
Choosing 7075-T6 for thick plate
At the center of thick plate 7075 does not reach full strength, and T6 is susceptible to stress corrosion cracking. For thick plate, 7050-T7451.
Welding 7050
Fusion welding creates cracks and a weak zone. Join with bolts or rivets.
Ordering without a temper
T7451 and T7651 differ in corrosion resistance. The drawing should state the temper.
Equivalents, standards and supply
| EN | 3.4144 |
|---|---|
| ASTM | 7050 |
| AMS | 4342 |
| Standards | ASTM B209 / AMS 4342 |
| Forms | plate · rod |
| Producers | Alcoa · Constellium · VSMPO · Kaiser |
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