7075 ALUMINUM ALLOY MATERIAL PROPERTIES

Aluminum 7075 is the major alloy in 7000 Series and zinc and copper are the major alloying elements. It possesses high static strength and is used in airframe structures and for highly stressed parts. 7075 is available in several types of tempers such as T6, T651, T73, T7351 and T76.

T6 temper has the highest strength but lowest toughness and resistance to stress-corrosion cracking. Since toughness decreases with a decrease in temperature, the T6 temper is not generally recommended for cryogenic applications. The T73 temper provides much improved stress-corrosion resistance over T6 temper with a decrease in strength. The T76 temper provides improved exfoliation resistance and limited stress corrosion resistance over T6 temper with some decrease in strength.

Alloying content of aluminum 7075 is given in the following chart.

Aluminum 6061 Content (% by weight)
Content Wt. % Content Wt. %
Aluminum 87.1 - 91.4 Iron Max 0.50
Silicon Max 0.40 Copper 1.2 - 2.0
Manganese Max 0.30 Chromium 0.18 - 0.28
Magnesium 2.1 - 2.9 Zinc 5.1 - 6.1
Titanium Max 0.20 Others Max 0.15

Some of the important temper designations of aluminum 7075 are summarized below.

  • T6 temper is solution heat treated and then artificially aged.
  • T651 temper is solution heat treated; stress relieved by stretching then artificially aged.
  • T73 temper is solution heat-treated and then artificially overaged in order to achieve the best stress corrosion resistance.
  • T7351 temper is solution heat-treated, stress-relieved by stretching a controlled amount and then artificially overaged in order to achieve the best corrosion resistance.
  • T76 temper is solution heat-treated and then artificially overaged in order to achieve a good exfoliation corrosion resistance.
  • T7651 temper is solution heat-treated, stress-relieved by stretching a controlled amount and then artificially overaged in order to achieve a good exfoliation corrosion resistance.

Some of the characteristics of aluminum 7075-T6/T651 and 7075-T73/T7351 are summarized below.

Aluminum 7075 Characteristics
Characteristic Al 7075-T6, T651 Al 7075-T73, T7351
General resistance to corrosion Rated C (Should be protected against corrosion at least on laying surfaces)
Stress-corrosion cracking Rated C (Service failures with sustained tension stress acting in short transverse direction relative to grain structure; limited failures in laboratory tests of short transverse specimens) Rated B (No known instance of failure in service; limited failures in laboratory tests for short transverse specimens)
Workability (Cold) Rated D (Ratings are A through D)
Machineability Rated B (Ratings are A through E)
Brazeability, Gas and Arc Welding Rated D (No commonly used welding methods have been developed)
Resistance Spot and Seem Welding Rated B (Weldable with special techniques)

Aluminum 7075 Mechanical Properties:

Reference:

  • MMPDS-01, Metallic Materials Properties Development and Standardization (2003)
  • AA-FMA-17, The Aluminum Association, Forming and Machining Aluminum (1988)
  • AA-38, The Aluminum Association, Structural Design with Aluminum (1987)