"Ed Huntress" wrote in message
...

"Karl Townsend" wrote in message
...
I'm preparing to machine several AL 7075 T6 forgings...

"The Kid" (my son) tells me I should anneal before machining because
there will be hard brittle spots. Easy enough to do at the anneal temp
of 775 (not sure how long). But, then I haven't got T6 grade 7075 AL
anymore. How would I get it back to T6 grade?

Or, am I better off with plan "A"? Don't anneal.

Karl


Hi, Karl. 'Just stopped in to see if anyone talks about metalworking here
anymore. g

Stick with Plan A. If you have hard spots, your 7075 sucks, but you're
better off living with them if you do. If you want to anneal, it's 775 deg
F for 2 -3 hours.

Forget natural aging. Unlike 2024, 7075 has a hardening curve that runs
out for years. It's very unstable throughout its life in that state. To
get a true T6, it requires a fairly tricky two-stage heat-treat: solution
heat-treatment and quenching, followed by precipitation heat-treatment
(artificial aging).

Unless you want to get into all of that, you won't see T6 again after you
anneal the stuff.

Good luck.

--
Ed Huntress

Great Honk, Ed's Back!
Good to hear your voice, Ed.

Paul K. Dickman