7075 Aluminum Alloy
7075 aluminum alloy, supplied by GNEE, is a zinc-based aluminum alloy known for its high strength, excellent fatigue resistance, and moderate machinability. However, it is not suitable for welding and offers lower corrosion resistance compared with many other aluminum alloys. Due to its relatively higher cost, 7075 aluminum is typically used only in applications where lower-cost alloys cannot meet performance requirements.
This alloy is commonly available in several heat-treated tempers, including 7075-O, 7075-T6, and 7075-T651.
History
The 7075 aluminum alloy was first developed in 1936 by Sumitomo Metal in Japan. During the pre-war period, it was notably used in the airframe construction of the Imperial Japanese Navy's Zero fighter aircraft, highlighting its early adoption in high-strength aerospace applications.
Basic Properties
Like other aluminum alloys, 7075 aluminum has a density of approximately 2.73 g/cm³ (0.098 lb/in³), providing an excellent balance between strength and weight.
Mechanical Properties
The mechanical performance of GNEE 7075 aluminum alloy varies significantly depending on the temper condition.
7075-O (Annealed)
In the O temper (non-heat-treated) condition, 7075 aluminum exhibits:
Maximum tensile strength of up to 40,000 psi (276 MPa)
Maximum yield strength of up to 21,000 psi (145 MPa)
Elongation of approximately 9–10%
7075-T6
In the T6 temper, achieved through solution heat treatment and artificial aging:
Ultimate tensile strength ranges from 74,000 to 78,000 psi (510–538 MPa)
Yield strength ranges from 63,000 to 69,000 psi (434–476 MPa)
Elongation is typically 5–8%
7075-T651
The T651 temper, which includes stress relief by stretching:
Ultimate tensile strength ranges from 67,000 to 78,000 psi (462–538 MPa)
Yield strength ranges from 54,000 to 67,000 psi (372–462 MPa)
Elongation falls between 3 and 9%.
Applications
GNEE 7075 aluminum alloy is extensively used in aircraft structural components, including wings and fuselages, where high strength and low weight are essential. Its performance advantages also make it popular in other demanding applications, such as
Rock climbing and mountaineering equipment
High-performance bicycle components
R/C hobby-grade chassis plates (commonly using 7075-T6 and 6061)
Military applications, including components for M16 rifles used by the U.S. armed forces
While alternative alloys such as 7005 and 6061 are also used in some industries, 7075 remains a preferred choice when maximum strength is required.
7075 aluminum is a high-performance aluminum alloy with distinct characteristics, including very high strength, moderate corrosion resistance, and poor weldability. Its properties result from a high zinc content combined with chromium additions. Zinc plays a dual role by promoting effective precipitation hardening while significantly increasing both yield strength and ultimate tensile strength. It strengthens the alloy by restricting partial dislocation movement, while the presence of chromium helps limit grain growth, thereby improving toughness and ductility.
Often referred to as 7075 aircraft aluminum or aviation aluminum, GNEE 7075 aluminum is extensively used in aerospace applications, particularly for aircraft structural components and skin panels. Structural parts are typically supplied in T7X series tempers, while aircraft skins are most commonly produced in the T6 temper. The fatigue performance of 7075 aluminum is comparable to that of 2000-series aluminum alloys, making it highly suitable for aircraft structures and rocket load-bearing components where strength and fatigue resistance are critical.
