Titanium help

Date 04-08-2005 19:21

I would like to know if anyone has any suggestions for equipment for titanium welding. It's a simple part, a machined round block with a two holes bored in it, and two port holes (approx.1/4 inch) drilled into the sides and intersect with the bores. A 1/4 inch plug is then inserted into the holes and seal welded, then ground flush with the O.D. of the part. The part is also pressure tested at 20,000 psi. This is the only titanium part we weld, so I was wondering what would be the most cost efficient set-up that would protect the weld from contamination. We had an enclosure that wasn't very good and produced the blueish discoloration around the weld when welding, also the parts where not allowed to cool in this enclosure, instead, taken out right after welding. We discovered there is more to titanium welding than we thought, so, any suggestions would be helpful.

By RODTESTER Date 04-09-2005 02:09

YOU MAY WANT TO TRY TO BUILD A COPPER BLOCK THAT THE UNIT WILL SIT IN. MAKE SURE THE THERE ARE HOLES IN THE COPPER TO DIRECT GAS AT THE WELD FRONT AND BACK IF POSSIBLE. ANTHER THING, IF YOUR WELDS ARE BLUE THAT MAY NOT MEEN YOU HAVE A PROBLEM WITH YOUR HOOD BUT WITH YOUR WELDER. TITANIUM IS HARD TO WELD. YOU NEED TO BE VERY CAREFULL WITH YOU GAS AND HOW IT FLOWS OVER THE WELD. YOU NEED SHELDING ABOUT .25 INCH BEHIND THE WELD PUDDLE. HOPE THIS HELPS

By ssbn727 (*****)

Date 04-09-2005 10:35

Hi Tito!

Please give us more info regarding your project such as; Grade of Ti, Thickness of material, current, type of tungsten, are you using a gas lens and as big of ceramic cup that you can get your hands on? What is the CFH of your shielding gas and is it a ultra high (around 10 to 40 parts per million max. of oxygen in the argon) purity grade of argon? The same goes for your trailing (are you using some type of trailing shield while welding?) and purging gas - need to know the Cubic Feet Per Hour flow rate coming out of your flowmeters.
Can you describe specifically what type of enclosure (collapseable or vaccum type?) you were using previously? What are you using to clean and prep the Ti prior to welding? Cleanliness is the key with Ti and so is the avoidance of ANY cross-contamination!!! In the enclosure, were you checking (O2 analyzer) the amount of oxygen in the enclosure's atmosphere?
Are you using a suitably matching or recommended filler metal?
If you can give us most of the info I noted, there's a strong possibility that amongst all of us that frequent this forum, enough suggestions and appropriate recommendations will be given to answer your questions...

BTW Rodtester, Ti is NOT THAT DIFFICULT to weld at all!!! It only requires a whole lot more preparation, awareness and understanding.

I look foward to hearing your responses Tito!

Respectfully,
SSBN727
Run Silent... Run Deep!!!

By welder5354 (**)

Date 04-10-2005 04:00

Tito, Titanium is an excellent material to weld. I just finished teaching a course at our facility on Ti.
Make sure that you have a backing gas, a trailing gas and of course you will have your torch gas. Use ERTi-2 for your filler metal.
Flowmeter will be set @ 30cfh. Use a foot, if possible. Set prepurge @ 5sec. and set post purge @ 40sec. After welding Ti. you must leave the tig torch on the crater until the base metal cools below 800 deg. or it will become contaminated (thats why we use postpurging). use a 3/4" cermic cup with a large gas diffuser.
A trailing shield can be omitted, if it is a small area, but only do an inch or two and then let it cool using the post purge.

By tito

Date 04-10-2005 22:45

Hello everyone,

Thanks for all the info, I'll be more specific in my next posting after I discuss all of the variables that we have been using; as opposed to the ones that we need to use. Again thanks for the help and Ill get back tomorrow.

By rodofgod (**)

Date 04-10-2005 22:48

Hi All!

Titanium is not hard to weld, at all!
what is hard is to keep oxygen away from the metal whilst it's cooling!

Titanium has a great affinity for O2! It will find O2 wherever it can! on your filler, in your gas or on your parent metal

Keep it clean and your troubles are minimal!

Use a gas lens, the biggest you can! Keep the 'hot' weld in the gas flow for as long as possible, let it 'cool' in the 'gas',not in atmosphere! That includes the 'filler' wire!
Keep everything 'clean' and under a inert gas till it cools and you should have no problems.

Regards

By tito

Date 04-15-2005 03:19

Thanks everyone for the info. I think the welder knows what he needs to do now. I havn't been with this co. long, and have had very little experience inspecting titanium, but one day I noticed the blue color on one of the parts and was pretty sure that meant a problem. I brought it to the attention of my supervisor. Obviously he had no experience with tiatanium because his reply was "doesnt all metal turn colors when you weld it?" Well, I did some research on this site and found very helpful info in another post. It seems the welder had no idea what precautions to take, such as the purity of argon, the cleanliness.....ect. So after my research, I brought it to the attention of my supervisor and the manufacturing foreman, and they finally realized there was a problem. After who knows how long!!! I think now everybody knows how to handle titanium a little better now. Thanks ya'll.