Titanium cold forming

I'm doing an univerity research about titanium cold forming, expecially in very thin foils (0,05mm thickness), used for tweeter
domes. I know that is very difficult to draw titanium foils since there are problems due to local thinning and subsequent cracking. I know that lubrication is critical in this kind of operation. I would like to know which is the best way to draw titanium foils, the best titanium alloy for this kind of operation(I think it is grade 1), how to lubricate it (coating or other way)and if it is possible to use traditional dies or it is necessary to have special dies. I would appreciate any suggestion about books or papers about the argument.
Thank you in advance. Lele
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"grade 1" is meaningless.

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On Wed, 13 Apr 2005 14:05:42 GMT, "bainite"
Why?
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It could mean anything without knowing the alloy at least. A grade is a variation of the basic material as described and required by a material specification. You have not stated either an alloy or a specification let alone a heat treat condition. With a few more details we can usually provide an educated guess. I can't do even that with "grade 1".
For example, in comercially pure titanium there are four common variations with different properties. Some specs might call this grades. For Ti 6Al-4V there are two major chemistry variants and three major heat treatment condictions. Are those grades? There are also several minor variants of heat treatment for Ti 6Al-4V. This does not include literally dozens of other alloys and heat treatments of each.
Help narrow the field. Learn enough to ask an answerable question. Start with the material you are considering. Get alloy and spec then tell us your intended purpose.

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On Mon, 18 Apr 2005 17:15:13 GMT, "bainite"
For Ti (certainly in UK practice) the "grade" implies the alloy.
"Grade 1" (and several others) is pure Ti, with no deliberate alloying and the impurites below certain quanitifed levels. There are something like two dozen grades and about six of these are "pure", for varying levels of purity. I'm unsure of the precise values (I'm a smith, not a metallurguist) and you no doubt have better references than I do, but "grade" is certainly a recognised way of specifying Ti alloys, at least in my country. "Grade 4" is the general grade of CP that I encounter, but that might be a grade mainly used for drawing seamless tube.
I'm not certain if grade also implies the heat treatment (I'm going to hand forge this stuff, so I don't care). However my suppliers offer particular grades as "standard" and "annealed", so they consider it worthwhile to separate the grades, even when they've all been annealed.
--
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Andy Dingley wrote:

For sheet titanium, I'd refer to MIL-T-9046. http://assist.daps.dla.mil/docimages/0002/54/55/9046J.PD0
Composition 1 through 4 is commercially pure titanium with minium yield strengths of 70, 55, 40, 25 ksi.
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Even in UK, specs you must go to the specification to get the definition of grade. "Grade" is meaningless without it. And yes, I am a metalurgist. I earn my living answering these questions. BTW- "Bainite" is a steel microstructure.

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On Wed, 20 Apr 2005 16:44:33 GMT, "bainite"

No, you don't need to go the specification, because you (or at least I) very rarely need to know the definition. A piece of steel labelled "Extra crunchy tool steel" _is_ meaningless, because no-one else knows what that means. For Ti though, these grade numbers are well-defined and controlled. I don't know what their _definition_ is, and given how scary Ti phase diagrams are, I don't want to know. But with my engineer's hat on I can order some stock over the phone as "Grade 4" and know that what I'm getting is up to the job. Somewhere a metallurgist once worked out what it was good for and how much unobtainium impurity was permissable, but that's just not my problem any more - I deal with a part number, not a composition.
"Grade 1" is meaningful for Ti in a way that "Grade 1" wouldn't be meaningful for steel (although EN45A or 316 might be). Even if I don't know what this implies, I can still choose the stuff, buy some and make things out of it.
BTW - The one on the left is grade 1 Ti, the others are just plain mild steel
http://codesmiths.com/shed/things/shiny/cloak_pins.jpg
Biggest is about 2" across

No shit ! Ever thought that people bothering to read an obscure sci.* group might already know things like that ?
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wrote:

As Mr. Dingley wrote, Ti grade 1 is commercially pure unalloyed titanium (you can find a lot of specification surfing on internet); it seems to be the best for cold forming operations, expecially when low in oxygen. I will be glad if anyone could indicate me how to form it in order to obtain a titanium dome for tweeters. Have a nice day. lele
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