Have you looked at AMS 4903 or 4904? I did not review these documents entirely, but they might help. There are other AMS standards reflecting Ti-6Al-4V....try IHS.
Solution treating + aging Ti-6Al-4V can possibly attain 180 ksi ultimate tensile strength, depending on some other factors (oxygen content, prior thermomechanical processing, etc.). Refer to the various SAE AMS stds or MIL-HDBK-697 and MIL-H-81200 for more information.
Conventional heat treatment processing limits Ti 6AL-4V to about 160-KSI.
Fastener vendors claim up-to 180 KSI for "titanium bolts"... but, from various discussions... it is obvious they are using a proprietary blend of materials, thermal treatments and strain hardening of the raw-stock to "get there". Conventional machined parts would have to be fabricated from this highly processed raw-stock to have close to this strength... then risk low fracture toughness due to the extreme hardness (there will be a very small difference between FTU & FTY. If You positively need these properties, then talk with titanium fastener manufacturers that claim to have Titanium fasteners performing at the at 180 KSI sstrength level... and have them give you a fabrication proposal.
Note: hogging parts from this material would probably be a nightmare due to the incredibly hard-machining nature of titaniun... agravated by the increased strength levels.
Perhaps another Titanium alloy would be more appropriate for Your needs: there are several "newer" alloys [or with better processing] that have higher properties [+170-KSI] becoming available in plate, sheet & bar.
To get the 160 ksi min bolt material they stretch the barstock before ageing it (this is also done with the high strength varieties of A-286 and Inco 718). Some of the 160 ksi minimum bar will come out at 180.
To go to 180 for titanium it's "usual" to go for 10-2-3, which has a MIL-HDBK-5 (ok, ok, MMPDS) condition of 180 ksi for die-forged material up to 1" thick (S-basis only). This stuff's toughness should be reasonable (40 ksi.sqrt" quoted in MIL-HDBK).
Cold reduction before after solution treating and before aging is not required for 6Al-4V Ti bolt material to achieve 160 ksi UTS. Typical aerospace bolt fabrication practice is to buy annealed material and to solution treat and age "blanks" in-house (after head forming/forging) to 160 ksi. The specifications they procure the material to require "heat treat capability" testing/certification of a sample of the as-shipped raw material after solution treament and aging (with no intermediate cold reduction) to the applicable tensile requirments.
I (like Wil) would be very, very cautious about the toughness of 6AL-4V Ti "pushed" to 180 ksi...
Kenneth is quite right. How I got cold work for Ti-6-4 bolts in my head I'm not sure.
Igearhart: I'm not familiar with 38-6-44. I've got a bit on it in the ASMH (from 1975), but Googling it doesn't yield very much. Any other sources of info?
Ti-3Al-8V-6Cr-4Zr-4Mo is also known as Beta-C. It is a common Ti alloy for spring applications. It is the alloy specified in SAE AMS 4957 and 4958. You should be able to find info from Timet, Allvac, Carpenter, or Perryman.
Sorry for late reply, I've been out of the circuit for a year. Ti6Al4V in solution/annealed condition is specified at 160 ksi min in bolt specs. 180 ksi has hardly ever been encountered, and would certainly not fit as a 6-4 specification min. in any heat treated condition. Problems in through-quenching (water) mean that even 160 ksi is not always achieved in large-diameter bolts. Better to go for a beta-c titanium alloy or 5-5-5, (assuming it's a forged piece - if it's 100 percent machined, good luck with your search)
