Solder or Weld to Titanium?

[German_EE]

Can you solder to titanium or do you always need to weld to it?

[ZeTeX]

http://www.finishing.com/277/00.shtml

[David Hess]

I found this answer from that link interesting and I remember reading that discussion before:

I have just finished soldering a broken hinge of a Flexon bow. I used silver-bearing solder and plain yellow flux paste.

I repaired a friend's titanium glasses using 50% silver brazing solder and the standard white flux (potassium fluoride and borax?) without problems.  One thing that surprised me is that titanium is pyrophoric which I discovered when I bead blasted the joint before and especially after brazing it.

It was so easy that I thought maybe the frames were actually stainless steel but I have never seen stainless steel exhibit pyrophoricity when bead blasted.  Do they alloy titanium with zirconium?  Maybe that would explain it.

[cncjerry]

sure they weren't magnesium?  I heard once magnesium engine blocks in F1 cars will burn to ash and all the equipment on a high tech fire truck won't put it out.

[T3sl4co1l]

Very finely divided titanium (usually hot from the division process -- grinding or sandblasting) ignites in air, burning brilliantly white.

Zirconium? Probably, but not much, as it's expensive, chemically similar (so it takes a lot to accomplish anything, much as with alloying nickel and iron for example) and, when it is needed, is better used nearly alone (i.e., zirconium cladding for nuke fuel).

Tim

[vodka]

you can solder with a system laser


https://youtu.be/4tKbDzQHJ_c

[Kleinstein]

I won't expect intentionally added zirconium, but likely some as an impurity. More likely alloying elements are aluminum and nickle.

Titanium like aluminum and magnesium can burn, but is normally protected by a quite stable oxide layer. Due to poor thermal conductivity in titanium it's even possible that chips during drilling / turning might ignite.

[German_EE]

Thanks for all of the replies folks, repairs will be underway this afternoon.

[David Hess]

sure they weren't magnesium?  I heard once magnesium engine blocks in F1 cars will burn to ash and all the equipment on a high tech fire truck won't put it out.

We threw a magnesium engine block onto a beach fire once.  The local authorities were not amused.

I was told they were titanium and they had the typical thin metal construction of stainless steel frames and after bead blasting they looked like the titanium I have seen.  The magnesium frames I have seen are much thicker.

And would silver brazing have worked on magnesium?  The melting point for 50% silver solder is 200F higher than for magnesium.

[T3sl4co1l]

Besides needing the special flux, and having a rather low melting point, magnesium forms brittle intermetallics with silver solder elements, so it's probably not very good.  (For higher melting base metals, like titanium, this is still true, but they tend to be stronger; but more importantly, the higher melting point of the base metal means less diffusion, so the interface layer is thinner and less fragile.  This won't be the case with magnesium.)

Probably, regular soft solder alloys (including zinc and tin, but not lead) are the way to go.

Tim

[David Hess]

Another reason I think they were titanium is that they were the "twistable" kind of frames.

I did not know what kind of result using 50% silver brazing solder would produce on titanium but since the frames were already broken, there was nothing to lose.  I think something got dropped on them breaking them at a joint.  The resulting silver brazed joint withstood all of the physical tests I could use short of destroying them so I and my friend were happy.  The original finish on the frames looked like bead blasting so when I bead blasted the joint after brazing, it was difficult to even tell that there had been a repair.

[SeanB]

I silver soldered my Titanium frames when they broke, though I did have to fix that join again when I dropped them again.

I was reading today about a new Titanium gold alloy, which is literally harder than diamond, by a factor of at least 4. Only issue with making it is that you almost have to heat the gold up to it's boiling point to make it.

[T3sl4co1l]

I silver soldered my Titanium frames when they broke, though I did have to fix that join again when I dropped them again.

I was reading today about a new Titanium gold alloy, which is literally harder than diamond, by a factor of at least 4. Only issue with making it is that you almost have to heat the gold up to it's boiling point to make it.

I guess this?
http://www.atlasobscura.com/articles/a-titaniumgold-alloy-harder-than-most-steel-was-just-discovered

A rather dumbly written report: osmium is the hardest metal, IIRC (Matweb gives 670 Vickers hardness; other sources suggest tungsten or chromium, but I can't find numbers nearly high enough to compare).  Osmium I suppose is naturally occurring, but always as an impurity in platinum; titanium is never "naturally occurring" (pure, metallic, out of the ground).  Steel was invented historically, so we didn't have to "invent" anything, and pure titanium wasn't prepared until 1910, anyway.  And if they had so much as checked Wikipedia, they would've found work referenced, since at least 2000, of the alloys' use in dentistry, apparently. https://en.wikipedia.org/wiki/Titanium_gold

As for the factor of 4, I guess that's over other intermetallics in the Ti-Au system, which is rather less impressive.

Nothing in the Ti-Au system has a melting point higher than pure Ti, so there will be no need of obscene temperatures.  Only a vacuum or inert gas environment, and an arc (low vacuum) or induction (any pressure) melting process will be needed.

Tim

[Fungus]

IIRC "Iron" Man's suit is made from titanium-gold alloy and that's from 2008...

[Kleinstein]

The super flexible titanium is an about 1:1 alloy with nickle.
The trick for the glassed is not a high strength, but a kind of super elasticity. With TiNi (high quality) one can bend a sample of about the shape of a pencil to U-shape, and it comes back perfectly strain again when you remove the force. So it behaves more like a very stiff type of rubber, not like an normal metal. Between the normal elastic and plastic range there can be an extended range of rubber like behavior: it can be reversible stretched to quite an extent at nearly constant stress.

A flux that contains born oxide is likely a really good idea, as this is one of the few ways to get rid of the oxide layer.

[David Hess]

The super flexible titanium is an about 1:1 alloy with nickle.
The trick for the glassed is not a high strength, but a kind of super elasticity. With TiNi (high quality) one can bend a sample of about the shape of a pencil to U-shape, and it comes back perfectly strain again when you remove the force. So it behaves more like a very stiff type of rubber, not like an normal metal. Between the normal elastic and plastic range there can be an extended range of rubber like behavior: it can be reversible stretched to quite an extent at nearly constant stress.

A flux that contains born oxide is likely a really good idea, as this is one of the few ways to get rid of the oxide layer.

Then I assume the nickel content would then explain why simple silver brazing worked so well.  I guess I lucked out that the standard flux uses borate.  Using a bead blaster to clean the surfaces probably helped as well.

[T3sl4co1l]

FYI, NiTi = Nitinol, a shape memory alloy (one formulated to be superelastic at room temperature, and plastic at low enough temperatures not to mind).  Definitely not pure Ti, though it will behave that way chemically for the purposes of solder and flux.

Tim