7075 Aluminum Alloy

7075 Introduction to Aluminum Alloy:

7075 aluminum alloy is a cold-treated forging alloy with high strength, which is far superior to mild steel.

7075Alu is one of the strongest alloys commercially available. General corrosion resistance, good mechanical properties and anode reaction.

Smaller grains allow for deeper drilling performance, increased tool wear resistance, and exceptional thread rolling.

Zinc is the main alloying element in 7075.Adding magnesium to the alloy containing 3%-7.5% zinc can form MgZn2 with significant strengthening effect, which makes the heat treatment effect of the alloy far better than that of the Aluminum-zinc binary alloy.

With the increase of zinc and magnesium content, the tensile strength of the alloy will be further increased, but the ability to resist stress corrosion and spalling corrosion will be decreased.Under heat treatment, can achieve very high strength characteristics.

7075 materials are generally added with a small amount of copper, chromium and other alloys, among which the 7075-T651 aluminum alloy is particularly high quality, known as the best aluminum alloy products, high strength, far better than any soft steel.The alloy also has good mechanical properties and anode reaction.

Representative applications are aerospace, mold processing, mechanical equipment, fixture, especially for the manufacture of aircraft structures and other requirements of high strength, strong corrosion resistance of high stress structure.

7075 Aluminum alloy corresponding grade:

• Chinese standard :7A09 GB/T3190–2008
• Japanese Standard :A7075 JIS H4000-1999 JIS H4080-1999
• Non-standard :76528 IS 733-2001 IS737-2001
• Russian standard :B95/1950 ROCT 4785-1974
• EN: EN AW – 7075 / AlZn5.5 MgCu EN573-3-1994
• German standard: AlZnMgCu1.5 DIN172.1-1986 / w – 3.4365 / nr
• French standard :7075 A-Z5GU NFA50-411 NFA50-451
• BS 1470-1988 7075 C77S BS 1470-1988
• American standard: 7075 / A97075 AA/UNS

7075 Chemical composition of aluminum alloy:

7075 Mechanical properties of aluminum alloy:

Basic properties

Aluminium 7075A has a density of 2.810 g/cm³.

7075-0

Un-heat-treated 7075 (7075-0 temper) has a maximum tensile strength of no more than 280 MPa (40,000 psi), and maximum yield strength of no more than 140 MPa (21,000 psi). The material has an elongation (stretch before ultimate failure) of 9–10%.

As is the case for all 7075 aluminum alloys, 7075-0 is highly corrosion-resistant combined with generally acceptable strength profile.

7075-T6

T6 temper 7075 has an ultimate tensile strength of 510–540 MPa (74,000–78,000 psi) and yield strength of at least 430–480 MPa (63,000–69,000 psi). It has a failure elongation of 5–11%.

The T6 temper is usually achieved by homogenizing the cast 7075 at 450°C for several hours, quenching, and then ageing at 120°C for 24 hours. This yields the peak strength of the 7075 alloys. The strength is derived mainly from finely dispersed eta and eta’ precipitates both within grains and along grain boundaries.

7075-T651

T651 temper 7075 has an ultimate tensile strength of 570 MPa (83,000 psi) and yield strength of 500 MPa (73,000 psi). It has a failure elongation of 3–9%. These properties can change depending on the form of material used. The thicker plates may exhibit lower strengths and elongation than the numbers listed above.

7075-T7

T7 temper has an ultimate tensile strength of 505 MPa (73,200 psi) and a yield strength of 435 MPa (63,100 psi). It has a failure elongation of 13%.

T7 temper is achieved by overaging (meaning aging past the peak hardness) the material. This is often accomplished by aging at 100–120°C for several hours and then at 160–180°C for 24 hours or more.

The T7 temper produces a microstructure of mostly eta precipitates. In contrast to the T6 temper, these eta particles are much larger and prefer growth along the grain boundaries.

This reduces the susceptibility to stress corrosion cracking. T7 temper is equivalent to T73 temper.

7075-RRA

The retrogression and reage (RRA) temper is a multistage heat treatment temper. Starting with a sheet in the T6 temper, it involves overaging past peak hardness (T6 temper) to near the T7 temper. A subsequent reaging at 120°C for 24 hours returns the hardness and strength to or very nearly to T6 temper levels.

RRA treatments can be accomplished with many different procedures. The general guidelines are retrogressing between 180 and 240°C for 15 min 10 s.

The mechanical properties of 7075 depend greatly on the tempering of the material.

Simple comparison between 7075 and 6061

In most cases, 7075 aluminum material material is indeed superior to 6061 material. But we can’t simply conclude that 7075 is better. Again, you need to define your purpose and budget first.

In general, 6061 can basically meet the general industrial manufacturing requirements. And 7075 is used in the occasion of high requirements, such as aerospace, military supplies, precision equipment, high-end electronic equipment, high-end products, etc.

Applications

1. Aircraft fittings
2. Gears and shafts
3. Missile parts
4. Regulating valve parts
5. Worm gears
6. Aerospace/defense applications
7. Automotive