lugged titanium

[markbeaver]

So, I've been wondering for years - any metallurgical reason why you shouldn't silver-braze titanium tubing into stainless lugs? You need a gas purge for welding ti, but do you need it for silver brazing temperatures? Could you silver braze ti just like steel? Anyone tried it?

Mark Beaver
Tamarack Cycles
Halifax NS Canada

[CyclesNoir]

Apparently it doesn't work. Freddy Parr has done a bit of research in this area (not merely for lugged bikes), and feels the correct flux/filler combo can do the job, but hasn't got the formula down yet.

You should be able to find his contact info at www.cycledesign.org. He'll be happy to take your call and explain what's what.

[shiggy]

So, I've been wondering for years - any metallurgical reason why you shouldn't silver-braze titanium tubing into stainless lugs? You need a gas purge for welding ti, but do you need it for silver brazing temperatures? Could you silver braze ti just like steel? Anyone tried it?

Mark Beaver
Tamarack Cycles
Halifax NS Canada

Bruce Gordon has done lugged Ti, with fabricated Ti lugs and adhesive bonding.

[Clockwork]

There's an old framebuilder's story that Cecil Behringer took the secret of brazing titanium to his grave.

http://www.classicrendezvous.com/USA...pinos_fork.htm


Attachment 14280

[Archibald]

There's an old framebuilder's story that Cecil Behringer took the secret of brazing titanium to his grave.

http://www.classicrendezvous.com/USA...pinos_fork.htm


Attachment 14280

It's no secret if you hearth braze in an inert atmosphere. The problem is for your average builder to pull it off without those kind of a$$et$.

[BentChainring]

So, I've been wondering for years - any metallurgical reason why you shouldn't silver-braze titanium tubing into stainless lugs? You need a gas purge for welding ti, but do you need it for silver brazing temperatures? Could you silver braze ti just like steel? Anyone tried it?

Mark Beaver
Tamarack Cycles
Halifax NS Canada

Titanium forms a tenacious oxide layer that cannot be reduced (broken down) by much of anything (which is why titanium compounds are often used in Flux!). When you TIG weld Ti, you are excluding the oxygen from the local area. Any oxygen that does make its way to the molten puddle dissolves in the liquid titanium. Also, most of the commercially available alloys used for furnace brazing titanium are quite brittle, and will probably require a dedicated Titanium furnace, as they often use special materials as oxygen 'getters' which can wreak havoc when brazing metals other than Ti.

//After doing some reading it appears that you should be able to use Transient Liquid Phase bonding to braze titanium tubes to titanium lugs... but I believe you will still end up with brittle intermetallic phases without extended hold times at brazing temperature.