Titanium

[Moritz]

What is the best method to weld titanium? Perhaps a stupid question, but I have not worked whit titanium before...

[Metal Demons]

It's a bit tricky. Titanium welds tend to end up brittle if you're not careful. TIG is essential, as is proper weld preparation - clean with alkali or steam and then further with acetone or another organic solvent and make sure it stays that way before welding.

Assuming you're using grade 5, you'll want to weld it with a grade 4 filler rod (a pure grade as opposed to the alpha/beta alloy grade 5 / 6al-4v, slightly less strong but helps avoid weld embrittlement), with high flow argon assist gas on both sides of the material - the whole area needs to be kept flooded with argon until it cools below about 300C. The argon needs to be high purity too.

The problem is that titanium is very reactive and tends to react with oxygen and/or nitrogen in the air - the result is welds that break.

My best advice to you is to get it done somewhere with plenty of experience welding titanium - it's fairly expensive to make mistakes with. Welding lower grades is easier but they aren't particularly worth using as they don't have the advantageous mechanical properties of 6AL-4V. 6-6-2 and some other alloys are even stronger but are basically unweldable so don't even bother trying.

[Moritz]

Perhaps it would be better to make angles in steel, and bolt the armor together, instead of welding??

[Moritz]

What kind of titanium is best to use in bolted armor?

6-6-2 or 8-1-1, or some other alloy???

What kind do builders prefer to use?

[Metal Demons]

What kind of titanium is best to use in bolted armor?

6-6-2 or 8-1-1, or some other alloy???

What kind do builders prefer to use?

6AL-4V is probably the most widely available alpha/beta alloy and is one of the strongest - that's your best bet. 6-6-2 is another alpha/beta alloy with slightly higher hardness and tensile strength, though lower fracture toughness.

6AL-4V would be best by a long way for your outer armour - I'm using a fully welded 6-4 shell on my spinner with 6-6-2 top and bottom plates (which aren't so likely to take massive impacts). Take a peek at my thread in the build diaries section if you want.

[Moritz]

Thanks for the advice.
It´s worth alot to me since I dont have that much experience of Ti.

And your robot Berzerker looks really evil...
I think that machine will be a great robot.

[psycho_fling]

Just to let you know my sponsors do all my ti welding and are able to cut most grades and thicknesses to sizes you desire and then weld them up

i have not had any trouble with the welds both on my 1.8mm and 5mm sections

check out my signature for details of t jones fabrications i can send further contact info if you want???

alex

[razerdave]

Just a quick thing with regards to Titanium, and I may sound like an idiot, but I am genuinly curious: Why are titanium sparks white whereas other stuff tends to be yellow/orange ?

Any thoughts ?

[Metal Demons]

Just a quick thing with regards to Titanium, and I may sound like an idiot, but I am genuinly curious: Why are titanium sparks white whereas other stuff tends to be yellow/orange ?

Any thoughts ?

Titanium burns hotter, basically - the dust thrown off by the grinding wheel or whatever is heated to a high enough temperature to burn in the air, and titanium burns white hot rather than only red-orange hot