how hard is 7075

[jpatz18]

How hard is aluminum 7075 to lathe? Its the hardest but it is still Easy and easy on the tools?

[scadvice]

Your question is not complete, 7075 comes in a number of tempers F, O, H, W and T. There are 3 subdivisons H1 H2 H3. The degree of Strain hardened are next and follow the second digit following one of the two above, 2 = 1/4 hard, 4 = 1/2 hard 6 =3/4 hard, 8 = full hard. and lastly 9 = extra hard.
Anyway the most common 7075-T6 or T651. It is very nice to machine and has a tensile strenght of 83,000 psi and yield of 73,000 psi. So to kind of answer your question... if I look up 83 ksi that = 170 Brinell hardness. However most references list it at only 150 Brinell and I'm not sure why.
Steve

[Scanfab]

7075 Al is a blessing to machine. It's hardness makes it machine in a "crisp" manner, low galling on tools. Any AL specific tooling (sharp) is a good start for lathe and mill. Just beware that if you remove a lot of material from for example one side of a plate, it will warp(banana) when the stress is relieved from the one side. In other words doing a rough cut on both sides of part before machining final surfaces might be in order.

Drill 1/4"-3/8" hole in drill press first into 6061 and then 7075, you will understand what crisp means...

[jpatz18]

its for T651. Thanks