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On Fri, 11 Feb 2011 22:49:30 GMT, (dan) wrote:

Karl Townsend wrote in
rec.crafts.metalworking on Thu, 10 Feb 2011 18:01:49 -0600:

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.

My vote is don't anneal. Hard spots in 7075 aren't like hard spots in
steels.
T6 is age hardened.
If you anneal, for instance, 6061T6 sheet to work it, and anneal it
again to take the working stress out, and leave it sit for a couple
months it is back to very close to T6 strength again.

Not sure how 7075 forgings will behave, but with the T6 designation I
suspect it would be somewhat similar.