"Paul K. Dickman" wrote in message
...

"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

Thanks, Paul. I'll try to keep my eyes open for questions to which I may be
able to contribute. This one happens to lie right in the heart of what I
researched and studied when I was materials editor at _American Machinist_.

--
Ed Huntress