Aluminum 7075 Parts

Strength is the whole point

7075 is a zinc-alloyed aluminum, developed in Japan in 1935 and used for airframes (source 1). In the T651 temper (solution heat-treated, stress relieved by stretching and artificially aged, source 7) it is listed at 500 MPa (73 ksi) yield and 570 MPa (83 ksi) tensile, and thicker plate may read lower (source 1). Typical yield for 6061-T6 is 270 MPa (39 ksi) (source 2), so 7075-T651 is nearly double. Source 1 also describes 7075 as resistant to fatigue. Parts that yield or bend under load in 6061 are the usual candidates for 7075, because yield strength is the number that changes. At 2.81 g/cm³ (source 1) it is about a third the density of A36 structural steel at 7.8 g/cm³ (source 3). The 6061 vs 7075 comparison sets the two alloys side by side.

One honest caveat: stiffness. The elastic modulus is 71.7 GPa for 7075 and 69 GPa for 6061 (sources 1 and 2), against 200 GPa for A36 steel (source 3). A part that deflects too much in 6061 will deflect nearly as much in 7075: it simply takes more load before it permanently bends. If your problem is flex, change the geometry; if your problem is yielding or fatigue, change the alloy.

Where it gets used

Source 1 lists 7075 in transport applications (marine, automotive and aviation) for its high specific strength, and in rock climbing equipment, bicycle components and off-road motorcycle crankcase guards. The machined parts that suit it are high-load brackets and mounts, robot arms and end-effector plates, motorsport hardware, and weight-critical parts that would otherwise be steel. The pattern is consistent: the loads are real, every gram is counted, and the part is bolted, not welded, into the assembly. It is quoted like any aluminum job, from one-off prototypes to repeat batches.

The fine print

7075 is hard to fusion weld. A 2019 University of California, Los Angeles study in Nature Communications names hot cracking (solidification and liquation cracking) as what has kept arc welding of 7075 from succeeding (source 4); 6061, by contrast, is described as highly weldable (source 2). Design bolted, pinned, or press-fit joints, or use 6061 if welding is non-negotiable.

Copper, iron and silicon significantly lower the corrosion resistance of aluminum alloys, and the source puts the 2000, 4000, 6000 and 7000 series in the most susceptible group (source 5); 7075 carries 1.2-1.6% copper (source 1). 7075 is also vulnerable to stress corrosion cracking (source 1). The overaged T7 temper, equivalent to T73, reduces that susceptibility at lower strength: 435 MPa (63 ksi) yield against 500 MPa (73 ksi) for T651 (source 1). If your part sees sustained stress in a corrosive setting, name the alloy and temper on the print.

The alloy is one thing that shapes a quote and the geometry is another, which is where design choices that raise a quote picks up.

Finishes

Type II anodize in clear or black is a common protective callout. Type II is a moderate-thickness sulfuric-acid coating and Type III hardcoat is thicker, and coating thickness raises wear resistance (source 5), so name Type III on the print where surfaces slide or wear. A finish called out on the print is quoted with the part. Dyed colors tend to vary with the base alloy (source 5), so dyed 7075 may not match dyed 6061 side by side. Note it on the print if an exact shade matters across mixed-alloy assemblies.

Sources

All accessed 4 October 2026. Where a figure here differs from your print, the print governs.

1. Wikipedia, “7075 aluminium alloy”: en.wikipedia.org (developed by Sumitomo Metal in 1935 and used for airframe production; 1.2-1.6% copper; T651 at 570 MPa tensile and 500 MPa yield, thicker plates may read lower; T6 yield at least 430-480 MPa; T7, equivalent to T73, 435 MPa yield and reduced stress corrosion cracking susceptibility; resistance to fatigue; vulnerable to stress corrosion cracking; density 2.81 g/cm³; Young’s modulus 71.7 GPa; uses in transport, climbing equipment, bicycle components and crankcase guards).

2. Wikipedia, “6061 aluminium alloy”: en.wikipedia.org (6061-T6 typical yield 270 MPa (39 ksi); Young’s modulus 69 GPa; highly weldable).

3. Wikipedia, “A36 steel”: en.wikipedia.org (density 7.8 g/cm³; Young’s modulus 200 GPa).

4. Sokoluk, Cao, Pan and Li, University of California, Los Angeles, “Nanoparticle-enabled phase control for arc welding of unweldable aluminum alloy 7075”, Nature Communications 10, 98, January 2019: pmc.ncbi.nlm.nih.gov (hot crack susceptibility during fusion welding a long-standing issue for 7075; solidification and liquation cracking the two dominant hot crack modes; 6061 a less crack-susceptible material).

5. Wikipedia, “Anodizing”: en.wikipedia.org (copper, iron and silicon significantly decrease the corrosion resistance of aluminium alloys, with 2000-, 4000-, 6000 and 7000-series most susceptible; anodizing thickens the protective oxide layer; Type II sulfuric acid coatings of moderate thickness, Type III thicker hard anodizing; thickness increases wear resistance; dye colors tend to vary according to the base alloy).

6. Wikipedia, “Machinability”: en.wikipedia.org (aluminium alloys do not tend to form built-up edges, so they rank as more machinable than materials that do).

7. Wikipedia, “Aluminium alloy”: en.wikipedia.org (temper designations: -T6 solution heat-treated and artificially aged; -T651 solution heat-treated, stress relieved by stretching, and artificially aged).