CP2 Titanium - Work Hardening, Annealing, Welding

snowman · Jan 5, 2023

I need a couple of "titanium buckets". Essentially a straight walled vessel with a radius into the bottom similar to any old stainless stock pot. Thickness...as thick as I can manually work, my guess is around 0.062". Overall dimensions are probably about 7" diameter, 12" tall? Awkward enough that the final welding will be a pain.

I've never worked with titanium before. Does it work harden quickly? I'll be forming a cylinder, then welding the seam, then hammering out the radius before I weld the bottom in. I'll probably have to rig up a glove box to weld it in, but I have no clue how to anneal it.

Anybody do this stuff?

Milland · Jan 5, 2023

You might check some of the videos and other links from this search: https://www.google.com/search?client=firefox-b-1-d&q=welding+titanium+bike+frames

While most will not be CP2, the basics will apply and the gauge isn't far off from what you'll be working.

Ti does work harden, and as Ti will absorb both oxygen and nitrogen at elevated temps the safest way to anneal will be in a vacuum furnace. Maybe a neutralizing flame with its soot would work?

cyanidekid · Jan 5, 2023

Milland said:
You might check some of the videos and other links from this search: https://www.google.com/search?client=firefox-b-1-d&q=welding+titanium+bike+frames

While most will not be CP2, the basics will apply and the gauge isn't far off from what you'll be working.

Ti does work harden, and as Ti will absorb both oxygen and nitrogen at elevated temps the safest way to anneal will be in a vacuum furnace. Maybe a neutralizing flame with its soot would work?

no, any flame combustion products. regardless of being reducing or not, will have WAY too much Co2 to shield Ti. steel, sorta, Ti, no.
this shape can be spun from a single sheet, with induction heat in a protective atmosphere id think. that's some specialized gear tho.
weld in a dry box, but really important, you CAN NOT rely on regular welding grade argon to be sufficiently pure to protect Ti. it needs
to be of specified grade, or certified in some way. contact a primary gas supplier in your area and discuss your application.

if you have some AWS people in your area, talk to them, and also the USN (Navy) has done a ton of work on developing standards for Ti welding.

snowman · Jan 5, 2023

Ouch....I knew it was sensitive, but didn't realize I couldn't do it with welding grade argon. That probably sinks this project. I've done a lot of inert gas chemistry, high and low temp, and welding grade argon has always been good enough.

Although I guess in a glove box you could do it by eating up the available oxygen using a sacrificial piece as a getter. Sounds like I need to think on this.

snowman · Jan 5, 2023

Is anyone aware of anything that uses a similar shape in a spun piece? I'd much rather just buy some weird spare part.

cyanidekid · Jan 5, 2023

depends on the particular supplier and tank, might be fine, might not. point is, you can't just hook up a tank (that would be totally fine tor GTAW welding steel) and go to work without spacial precautions to insure the purity of the shielding gas. you don't want to risk hunderds$ in material and even more in time.

Milland · Jan 5, 2023

Thanks for that info, Cyanide.

snowman · Jan 5, 2023

Well, what you are describing is something that I can't do with just an inflated "balloon" full of shielding gas. It's going to have to be evacuated and backfilled.

I guess it makes sense, that's the exact reason it has minimal scrap value. All the cost is in the processing premium.

Milland · Jan 5, 2023

snowman said:
I guess it makes sense, that's the exact reason it has minimal scrap value. All the cost is in the processing premium.

That's actually something that's confused me for a while. I think the minimal scrap value is more that the big users (Aero/Mil) demand virgin stock for best properties control, as the majority of the extra processing is getting to the metal sponge.

If there was a larger consumer market for Ti items, perhaps there'd be more value for scrap materials. Not sure, this is just my guess.

snowman · Jan 5, 2023

Milland said:
That's actually something that's confused me for a while. I think the minimal scrap value is more that the big users (Aero/Mil) demand virgin stock for best properties control, as the majority of the extra processing is getting to the metal sponge.

If there was a larger consumer market for Ti items, perhaps there'd be more value for scrap materials. Not sure, this is just my guess.

IIRC, Ti is graded as foundry or Arc Melt scrap. Arc melt scrap has to be free of mechanical damage and needs to basically be chemically pure. In many of these cases on the scrap side, as an owner of the scrap, you contract out the arc melting of the lot. You pay a set fee to melt it into a 40,000 lb lot that will be sampled multiple times. All of those samples have to maintain a purity standard that will determine ultimately what the whole lot is worth. If your sample doesn't uniformly meet the purity standard, the whole lot is now foundry scrap.

Foundry scrap is just used as additives. So when you have inconel chips, they use it in the steel smelter to increase nickel or chrome, whereas if you scrap out inconel drops, they just remelt it into more inconel.

snowman · Jan 5, 2023

So to better respond to your statement...there actually IS Ti scrap that has a very good market, but you have to know who to market it to and you have to have marketable quantities. Your average scrap yard that buys specialty alloys knows this, and knows that you don't have marketable quantities. Their risk is that the market will significantly shift before they hoard the marketable quantity so they can collect that premium.

Milland · Jan 5, 2023

Well, since my Crypto holdings have cratered, I'm putting everything into titanium metal scrap in the hope of cornering the market. I'm sure I'll be rich any day now!

snowman · Jan 6, 2023

Keywell LLC tried doing just that with the nickel alloys. They went bankrupt long enough to send all the customers "sorry bout that check" letters. Then the principles re-opened with a new name a couple years later. Their introductory letter quoted all kinds of industry experience, they just left out the part about leaving everyone high and dry.

Milland · Jan 6, 2023

snowman said:
Keywell LLC tried doing just that with the nickel alloys. They went bankrupt long enough to send all the customers "sorry bout that check" letters. Then the principles re-opened with a new name a couple years later. Their introductory letter quoted all kinds of industry experience, they just left out the part about leaving everyone high and dry.

I'd like to see some sensible rewriting of bankruptcy laws that would penalize that sort of BS.

cyanidekid · Jan 6, 2023

snowman said:
Is anyone aware of anything that uses a similar shape in a spun piece? I'd much rather just buy some weird spare part.

someone in the scrap biz near an aerospace industry hub would be my thought. SoCal, Tx, formerly LI,Ny (Grumman) but maybe still...

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