Titanium

Download Miller's TIG handbook from Miller's website. It is about 80 pages and discusses welding titanium (which has many gotchas). Check out sci.engr.joining.welding.
I never welded titanium, so all I know is what I saw in various reference books.
i

It tends to burn quite nicely when properly persuaded. I'd want to read up on it first, and perhaps have a fire department at the ready... / mark
Dave Ly> My employee wants to make a titanium roll cage for his high performance

Depending on the alloy, it probably can be welded. This is a project designed to gobble up money, obviously not for any practical use, as what the heck does an un-manned vehicle need a roll bar to protect, anyway?
You are going to have to use titanium filler rod. Since this is most likely going to be made out of solid Ti wire, anyway, you can probably use scraps of the original stock as the filler. You may need an additional TIG torch and a helper to apply enough shield gas to prevent a fire. The helper may need to apply shield gas to the opposide side of the weld, or to follow the welding torch to inert the just-welded but still hot metal until it cools. IF you did this on tubing, you might need to fill the tube with argon first, and then plug the bottom to keep it in.
I think Argon should be fine for Ti, and I'm pretty sure you don't want anything with oxygen in it, like CO2.
Jon

You'd be surprised. This little sucker does over 30 mph. He has a habit of running into telephone polls, curbs, and over very large jumps. He has broken 3 gas tanks, and multiple motor mounts in the last few weeks.
Of course, he could just buy a SS roll cage, but that wouldn't be as cool as titanium. :)
Thanks, that answers some of my questions. I called my welding supplier today. He said it had to be welded in argon, but he didn't know why. It must be because of that pesky little fire problem. They had filler rod for me, but I had to buy a minimum of $600.00 worth. I think instead, we'll just get a couple 1/16 pieces from McMaster-Carr.

It TIGs quite well. For high quality welds you need to back purge minimally or preferably work in a pure argon atmosphere.
For small work you can TIG it just like you would aluminium. It will be ugly where the gas doesn't shield it and it won't give maximum strength but it does hold. I watched a guy weld a sheet titanium pyramid in one of Ernie's classes a few years ago. I didn't think it would work but it looked great.
Cheers,
Kelley

Bicycle shops (design ones anyway) do it all of the time. Search for them on the net - maybe some hints.
Martin Martin Eastburn @ home at Lions' Lair with our computer lionslair at consolidated dot net NRA LOH, NRA Life NRA Second Amendment Task Force Charter Founder
Dave Ly> My employee wants to make a titanium roll cage for his high performance

: It TIGs quite well. For high quality welds you need to back purge : minimally or preferably work in a pure argon atmosphere. --If at all possible you'll want to do it in a big-ass glove box..
: and it won't give maximum strength but it does hold. ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ --What he said. I'd be particularly concerned due to the application; i.e. life saving. I've seen massively thick battlebot armor (3/8" thick plate) that has ripped apart at the welds due to *not* back-purging correctly. Something as wimpy as a rollbar would probably fail under a much smaller impact.. --Also, assuming you're planning to use Ti tube you'll want to bend it, yes? Not sure what this would entail but I'll bet it ain't trivial... ;-) --
"Steamboat Ed" Haas : Doodle doodle dee Hacking the Trailing Edge! : Wubba wubba wubba... ---Decks a-wash in a sea of words---

I've seen it done,but never done it myself. A friend used to weld 10 mm I.D. titanium filling tubes for a bleach bottle filler. When they were damaged, he dropped them into a small open topped tank which he consciously purged with argon before and for a minute or two after tig welding them. He used titanium filler rod,but I don't know where he got it from. It was quite successful, and the welds looked OK as well. Tom
"Martin H. Eastburn"
> Bicycle shops (design ones anyway) do it all of > the time. > Search for them on the net - maybe some hints. > > Martin > Martin Eastburn > @ home at Lions' Lair with our computer > lionslair at consolidated dot net > NRA LOH, NRA Life > NRA Second Amendment Task Force Charter Founder > > > > Dave Ly>> My employee wants to make a titanium roll cage >> for his high performance >> remote control monster truck. We have a good >> 185 amp tig welder, and he's >> pretty good at using it. We are using argon as >> a shield gas. >> >> The problem is, we've never worked with >> titanium before. Can it be Tig >> welded? Can we use stainless rod, or should we >> get something else. Is the >> argon OK? >> >> > >