Welding Titanium

If you Google "Welding Titanium" you will see....

www.welding-advisers.com/Welding-titanium.html

and

www.azom.com/Details.asp?ArticleID=1245

and much much more....

Yeah, I've googled it and talked to other welders that say it can be done, but has anyone actually done it? I am curious to get some first hand experience reports before I try it and damage some expensive pieces.

It is not going to be a cake walk. Maybe you should hire a trained/certified instructor and welder to teach you. It will probably be cheaper in the long run for you considering the costs of material, consumables and chamber.

I almost forgot the clean room...?

y

Yes, you can weld it rather easily with the right equipment and shielding gas. Use TIG with Argon, same filler as parent metal, shield backside with Argon, continue shielding the weld until it cools. -or- Suspend a bell jar (open bottom, closed top) large enough to contain the parts and give you working room to weld. Fill the bell jar with Helium from the bottom and keep it flowing while welding and until the parts cool. You need to work in a room with still air to avoid contaminating the Helium in the bell jar with air. I recommend doing this welding in your shop rather than on location. Sounds like someone wants you to do repairs at a race track (very difficult).

yes it can be done,way back in 1978 on Board a submarine where a perticular part of main engine ,made out of Titanium could not be teken out of submarine because of size and avilable openings were not allowing the part out of submarine ,we fabricated chamber made out polyethilyne sheets &flushed it with Nitrogen with part to be welded in the make shift chamber and welded the Titanium part with 100% success.al along the welding process the chamber was kept under nitrogen filled.entire welding process took less then an hour start to finish.

crm

I faced the same quandary more than fifteen years ago, Possein.

Consulting a lot of technical literature then, I found the Amercian Society for Metals' Handbook on Welding to be the best source. They have given extensive drawings and sketches for making : (The Handbook from American Welding Society is also very good, do consult it too)

a] a trailing shield for the GTAW torch, so that the welded Ti-alloy gets time to cool under the added shield gas, usually argon.

b] a special jig which is water-cooled or air-cooled, to hold the workpiece and shower it with additional shield gas,

c] a Gas Lens arrangement which can fit most of the standard GTAW torchs (you can buy one with a gas lens fitted to it.

I produced Ti welds as good as those produced in a controlled atmosphere chamber. For yet better results, go for micro-plasma welding configuration, which is far more easy to control than a GTAW torch. The plasma torch is insenstive to arc length variations, bound to happen with most welders.

Ask for more details, if need be.

Good luck,

Regards,

Plasmaspecialist.

Titanium reacts with oxygen, from the air, at high temperatures to make titanium dioxide, a substance commonly used in powder form as the white pigment in both paints and white bread.

So welding the metal needs to be done in an inert atmosphere for it to be successful.

Dear Crabtree,

Whilst I would not dispute your wisdom about having to weld Titanium or its alloys inside a controlled atmosphere chamber, you seem to imply that welding Ti/alloys is not possible in the open atmosphere.

The use of a 'trailing shield' to create an inert atmosphere during and just-after welding, with additional shilelding with an inert gas is done till Ti/alloys cool down to lower than 150 degrees C, so that the oxidation does not occur and the whitish powder does not form. For more please read ASM's Metals Handbook, the volume concerning welding techniques.

Regards,

Plasmaspecialist.

You have received lots of good advice. Normally an inert gas blanket is required because titanium reacts with both O2 and N2. You can skip the blanket if you resistance weld because the time at temperature is short, and the weld is completely surrounded by metal. If you need to arc weld, you will likely need a cover gas. I have arc welded titanium without the gas, but the welds were not high quality. I suggest that you invest in a TIG welder. A gas chamber is only required for parts that take a long time to get up to temperature, a long time to cool, or when the shielding gas can't reach the back side if the weld. A gas chamber need not be terribly expensive or complicated. I see them on eBay from time to time.

Small parts of Titanium can be easily welded using Argon trail shield or using any secondary inert gas shielding incorporated in the welding fixture. If required transparent collapsible chambers can also be used for one off jobs or small parts.

Trail shield method is used successfully for welding of small parts often . It is easy to design, fabricate and use. The nozzle size could be 19 mm to provide adequate shielding for the weld and a HAZ to avoid contamination. Of Oxygen and Nitrogen. Use laminar flow of the shielding gas , because even a slight turbulence in the gas flow induces air to mix with the gas .

If trial shielding is inconvenient for manual welding, then torch nozzle can be equipped with a outer shroud containing copper sheet/ ring to provide diffused and cooled additional gas shielding to receive extra supply of argon gas

Secondary shielding is provided by a trailing shield, a typical design It consists of metal chamber clamped to the to the torch nozzle. The inert gas flow through porous metal diffuser screen and impinges itself over the hot weld area. It's length ( usualy 8 - 10 " / 20 - 25 cm ) varies according to the heat in put and rate of weld travel speed. The shield should also cover width of HAZ ( 25 mm) on either side of the weld bead.

The secondary shield can also be incorporated in the welding fixture.

All these precautions are required as the alloy is sensitive to embrittlement by O₂, Nitrogen when heated above 260 ⁰ C. So, molten metal, solidifying weld metal, HAZ, Heated back side of the weld metal are to be protected, and avoid discolouring.

Sridhar - adv. institute of welding technology, Chennai -India.

Thanks SRIDHAR, that's the answer I was looking for. I have a trailing shield and have back purged stainless before. I have some pieces in the shop now that I can try it without a chamber. I suppose extending pre and post flow of argon would be a good idea as well.

Thanks!

Dear Possien,

Please go ahead, and U will never fail in your attempts. Please make sure that, the Argon gas is pure and with no moisture content. Other wise due break - up of water molecules, the O₂ generated during arcing will create endless pores , which are difficult to repair again. Take due precautions, and it will help to produce successful welds.

The difference between SS and Titanium is that, in SS U will have only oxidation at the root, but in Titanium, The HAZ may become brittle and followed by cracks at times.

Sridhar.

Most people agree that you need an inert gas shield, not nitrogen, for Ti metal welding. You do not want to start the Ti burning! You might also want to talk to some welders at places like Boeing Aircraft Co. for ideas.

Warning !

Inert Gases are deadly. Argon can fill a room from the bottom up and kill you or your child or pet. It can kill you by filling your lungs from the bottom up. You will die from suffocation because it is Inert.... your lungs can not absorb it. The symptoms are brain damage, unconsiousness, then coma, and death.

Ventilation is required and it should be monitored. Proceed with caution.

y