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heat treat titanium (6AL-4V) 7
- Thread starter engamopar
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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.
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engamopar
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.
Regards, Wil Taylor
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.
Regards, Wil Taylor
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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).
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).
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RPstress:
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...
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...
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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)
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