UTS of Titanium Bolts

[123Dog]

These people that change out cap screws for Titanium bolts From memory, you only get the weight saving ,,,,,,you dont approach the UTS or the fatigue resistance of a Socket Head cap screw do you ? Which from memory can be 190,000 PSI
Thanks

 

[Kenneth]

The minimum rated UTS of solution treated and aged, 6Al-4V titanium bolts typically used is aerospace applications is 160 ksi.

 

[CoryPad]

Here is a list from ARP (a respected manufacturer of high-strength fasteners) of materials - you can see that strength can reach 300 ksi (2000 MPa):

http://www.arp-bolts.com/pages/tech/matspec.html

One consideration is specific strength - strength divided by mass density, which is an indicator of potential mass reduction. Titanium alloys compete favorably in this respect.

For titanium fasteners, you can look at alloys other than Ti-6-4 and reach strength around 200 ksi (1400 MPa). Here is a link to SPS, another respected manufacturer:

http://www.spstech.com/aero/prod_lit/sps_racing_brochure.pdf

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[yates]

Ti6Al4V solution and aged bolts, as Kenneth says, are normally rated at 160 ksi UTS. Other grades of titanium alloy used for bolt applications are specified at UTS up to 200 ksi as Cory mentions.
I assume 123dog is referring to socket head cap screws in class 8.8 or 10.9. Most bolts with higher UTS tend not to be socket head cap screws anyway but 12-point heads, more suited to high-clamping applications. Consequently, there can be a slight strength advantage, even without considering the specific strength aspect.
The weight saving is considerable when replacing steel socket head cap screws with Ti6Al4V conical head bolts with a six-lobe socket (generically known as R-sat bolts)- a solution which has been adopted widely for satellite applications.

 

[strokersix]

123dog,

If you swap titanium in place of steel fasteners and need to increase the fastener size you might also need to increase the size of the bolted components as well. This may offset the mass reduction. Or, looking at it the other way, perhaps you can use a smaller size steel fastener and reduce component size for mass reduction.

 

[WKTaylor]

123Dog..

For aerospace, where fatigue and durability are critical, 160-KSI FTu is typical limit. See NAS4004

I have hear of auto-racing ti-Bolts pushed to 200-KSI... but then these engines/bodies are retired after just a few races.

Regards, Wil Taylor