stress relieving titanium

i have some parts that i'm machining out of 4" 6al4v titanium bar stock. I had them cut into .15" thick disks and i mill them down to .09", and cut about a 2.9" hole out of the center (it's not a round hole, there's a few small features in it so it cant be bored). As soon as i take it out of the chuck, it potato chips. I think pie jaws will help, but i was thinking of stress relieving them in a sandwich fixture to make them flat again. Any thoughts on this process? We've done it before at a place i used to work, but i dont exactly want to call them and ask how we did it. These parts are my product and i'll be making tons of them.
Thanks!
Dan

TI stress relieve is about 900-1,000 F. Your problem will be finding a material for a fixture that will remain stable.
JR

JRIowa said:

TI stress relieve is about 900-1,000 F. Your problem will be finding a material for a fixture that will remain stable.
JR

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The ti is thin enough where it wont distort any metal that is much thicker, and i was thinking of using something somewhat stable like a2.
We've done it before with very large (27 inch diameter, nearly 3 inch thick) ti rings and it worked great. We used 2.5" thick a36 steel plates with 3/4" studs to pull everything together. We had i tihnk 3 rings in there at a time. It took about 1/4"-5/16" of distortion out of the rings after it was all said and done.
I designed and built the fixtures, but i didnt have contact with the heat treaters so i dont know how they did it.

I may have found a solution without doing that though, they seem to pop back once i cut the outer profile. They dont need to be super flat, they get mounted to something that'll constrain them fairly well. I just like to start with something at least somewhat flat for peace of mind. Being parellel is much more important, which they are.
How long do you think i should cook them for if i decide to try this?
Thanks,
Dan

Annealing Ti

Annealing of Titanium: Residual stress can be removed by annealing the titanium at a temperature between 932 and 1112 degrees F. Full annealing is accomplished at about 1292 degrees F. Heating of narrow or thin items must be done in a vacuum or inert-gas atmosphere. Atmospheric annealing is sufficient for forging, thick plate, etc. However, it must be done in an oxidizing atmosphere. The titanium can be left in the furnace until it reaches room temperature.

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Source. There is some other useful info there also.

thanks! i guess i need to buy a furnace sometime soon. i need one to ht 17-4 anyways.