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This is great...I sign up for the singletrack forum and this is the first topic I stumble across! I am metallurgist you see (well, a Materials Scientist technically, but more metals than anything else) and I have a special interest in titanium alloys.
Welcome to STW Jon.
You are just what this forum needs. Somebody who [i]actually does know[/i] what they are talking about
silverpigeon - MemberThis is great...I sign up for the singletrack forum and this is the first topic I stumble across! I am metallurgist you see (well, a Materials Scientist technically, but more metals than anything else) and I have a special interest in titanium alloys.
Welcome to STW Jon.
You are just what this forum needs. [b]Somebody who actually does know what they are talking about[/b]
We don't want their type round here 😉
Didn't Specialized stop making their S Works frames in the US (in about 2001 i think) becasue Taiwan and the far east could producde better welds than the Yanks could?
The best Ti welds I've ever seen on a bike have been on Moots frames, no two ways about it.
You haven't seen my welding 🙂
you can get 6-4 ti tubing still (despite the rumours of its demise)
its not seamed welded tubing either
im assuming trent 900 you have something to do with that little firm that makes wirly round air suck through things down moor lane in derby
best welds i ever saw were on the trent 500 COC
what's a trent 500 COC ?
isn't pointing at welds and saying "ooh those are smooth" just another form of tyre-kicking?
what's a trent 500 COC ?
it's a jet engine isn't it?
isn't pointing at welds and saying "ooh those are smooth" just another form of tyre-kicking?
Certainly not. I'll have you know that modern fingers are capable of electromagnetic and ultrasonic NDT.
However visual inspection is sometimes enough to spot horrific welding.
[i]what's a trent 500 COC ? [/i]
Im gonna guess and say a combustor outer casing. In which case its most probably a Inco718 or C263 EBW weld. Harder to weld than Titanium!
All this talk of "quality welds" is nonsense. What you mean is how "pretty" the welding is. I see horrible looking welds pass aerospace acceptance standards / crack test etc, and i see "pretty" welds fail specs / crack test etc. Dont think a pretty weld always = a good weld.
Does anyone know if Titanium frames have the welds x-rayed? Seems a bit OTT for me.
popped into the local shop this morning, and whilst browsing came across this;
[img] 
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It has 2 screw like thingies, so that the frame can be taken apart and placed into a suitcase. This particular bike had 700c wheels, V brakes and was made up like a tourer. Quite nice really.
The screw thingies are made in the USA and then imported into China.
so then, could anyone tell the difference between the Lynsky and Airborne 456?
isn't pointing at welds and saying "ooh those are smooth" just another form of tyre-kicking?
funnily, people agonise/drool over that then throw their treasure down a trail that kicks up stones/grit etc as well. Madness.
I always get off and walk on anything 'down' for that very reason.
Does anyone know if Titanium frames have the welds x-rayed? Seems a bit OTT for me.
I think it is unlikely that any frame manufacturers do this. It would get added to the marketing blurb.
How do you know its chinese/Russian or US? Say a small boutique maker buys (unseen) through a factory who makes it for them? No way of knowing unless you listen intently in silence to see if it starts talking chinese/gibberish to you? 😆
[i]what's a trent 500 COC ?[/i]
It is a combustor outer for the Trent 500 engine, yes! C263 I think - not something I'm well versed in...nickel alloys...ugh. Heavy things. I work at the cold end of engines, on titanium, aluminium and magnesium alloys, some steel, and composites. Also known as bike frame materials! How handy.
I'm glad there's lots of people here who know that a weld that looks pretty is not necessarily a good weld. You can have a sexy looking weld with half a tungsten electrode in it. Oops.
Someone up-thread confirmed the availability of 6/4 extruded tube. I thought you could get it! It would be great stuff for strength-limited design (not as good as 15/3 though) but I think frames are stiffness-limited.
Someone else asked if frame welds were X-rayed - I have no idea. They wouldn't be easy to X-ray properly, I suppose, but if you could do it on thin tube it would be a sensitive technique. If it's at all possible it would be a good idea on hand-TIGed tube, that's all I'm saying. I'm think these are 6G welds (the hardest possible!), so I'd want mine inspected to death 😀
How do you know its chinese/Russian or US? Say a small boutique maker buys (unseen) through a factory who makes it for them? No way of knowing unless you listen intently in silence to see if it starts talking chinese/gibberish to you?
That's one way. You could ask your supplier for the material release certificate, but listening to the frame in silence is probably easier.
Given the choice between the two sources of Ti, I wouldn't care where the tubes are sourced to be perfectly honest. What really matters is how the frame is designed and who builds it. I don't subscribe to the notion the US builders are inherently better by dint of nationality nor by ****y marketing hype. I ride an Ibis Silk Ti, a Hummer and my missus has an Airborne crosser. To be honest, you'd be very hard pushed to tell the difference between the three despite coming from different factories. I love the dinky head tube badges on Indy Fabs but it's not enough to justify paying almost three times the price of a Van Nicholas.
So big up the far east - cheaper, ride just as well and safe in the knowledge that you can spend the money you save on more riding holidays!!!!! 😀
Cheers
Sanny
All this US / Chinese discussion just sounds like FUD (Fear, Uncertainty, Doubt) marketing to me. is there really any hard evidence that there more failures on either side in relation to the number of frames in circulation? And what proportion of frames on either side actually fail prematurely (for some value of 'mature')?