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Up Topic Welding Industry / General Welding Discussion / Welding Titanium
- - By Irv Ayers (*) Date 04-16-2011 01:29 Edited 04-16-2011 01:34
I need some advice on welding titanium. Its not pipe it will be anywhere from.125 -.750 plate welding. From corner joints, t-joints, and I believe open root in some cases. Now I do know that on the open root I need a back purge, now I've watched some video's and also talked with people. Some people that I talked with they say I need to have a argon shield right behind the torch to help keep any kind of contamination and the back purge. Now the video's that I watched the welder had the back purge but no shielding gas behind the torch. Also I was told the only way to weld titanium is welding it in a box of some sort under a constant purge. Also I was told if I have a bluish weld then its contaminated. The weld has to be all silver.   With all these opinions I'm confused so this is why I am turning to the experts... Can someone give me direction on this and let me know what I need the weld to look like and how I should weld this..

Thanks
Parent - - By Cactusthewelder (*****) Date 04-16-2011 02:13
You need a 100% Argon Atmosphere to weld it correctly. This may sound stupid, But a Clear plastic trash bag works wonders if the peices are not to large. Make some holes for your arms and lens, add a little duct tape and you are now welding Ti.
Parent - By joe pirie (***) Date 04-16-2011 13:44
welded some titanium pipe a few years back and i remember we had to get
a special type hose for the argon to prevent contamination. sorry don't recall
what type hose it was .
Parent - - By Lawrence (*****) Date 04-16-2011 22:36
Irv.

If your going to be doing thicknesses over .125 you really need to do some research before going into production..

There are many many posts here on the forum that can get you going in the proper direction also.

You do NOT need an atmospheric chamber to join Titanium with GTAW, but you do need some very high level process controls in place and you can't have those until you have done the research to know what they are and how to apply them.

When you begin to do your research look for these key terms...

1.    "Alpha Case"   This is a condition that occurs along with the oxide color that appears on titanium welds that are not properly covered by a trailing shield or have atmospheric contamination of some other sort.

2.  Surface prep

3. Alloy and filler selection>>>>>>>>  This should be covered somewhat by the governing code you are building to... But since you haven't mentioned any code compliance we will just leave it here for now.

As a last note of consern... Forget about "opinions"  When your dealing with Titanium you need guidelines that go beyond opinions if you want your work to be high quality at the least and code compliant if it is necessary.   A titanium weld can have perfect post weld color on the top and still be brittle as an eggshell if proper controls are not in place... Visual inspection is not a garuntee of acceptability.

Bring more specifics to the conversation and we can prolly point you in the right directions.
Parent - - By OBEWAN (***) Date 04-16-2011 23:55
We really should know what code he is welding to if any before saying a closed atmosphere is not required.

It is well known that even small amounts of oxygen can cause embrittement and poor toughness in titanium welds.

All of the Exxon specs I just finished working with require closed atmoshperes and even oxygen monitors to control to the PPM levels.  And argon to 99.997% purity.

As for oxides, the specs I am used to working with reject anything other than silver or very light straw/amber colored oxides and require welds that fail to be cut out.
Parent - - By Lawrence (*****) Date 04-17-2011 07:37
Of course your right I suppose.

My meaning is that GTAW welds of titanium can be made to the absolute highest quality and mechanicals without a purge box.

Code can requirem them... Physics does not.
Parent - - By Shane Feder (****) Date 04-17-2011 14:16
Hi Lawrence,
I think you will find it is project specifications that may require closed atmospheres.
I have never heard of a code that requires it.
Regards,
Shane
Parent - By Lawrence (*****) Date 04-17-2011 14:42
I'd really like to thank you both for taking the time out of your busy schedules to correct me.

Since the entire point of my post was to encourage the original poster to find out for himself what the requirements were for his project, your quibbling with me over sementacs will be like golden nuggets of wisdom to his ears.  You really saved him from my steering him toward a catistrophic failure.

The impact of your posts to this thread are too great to calculate.
- - By Irv Ayers (*) Date 04-22-2011 20:52
Hey thanks for your input guys. I do know we will be building mostly to the D1.1 structure code book and the Ti is 99% pure. I did more looking into it and do know that depending on the application we shouldn't need a total 100% controlled atmosphere area. I will be doing more research before any production though. If you guys have anymore input let me know.

Thanks guys,
  Irv
Parent - By qcrobert (***) Date 04-22-2011 22:29
In 1984-1986, I welded titanium pipe, 2" thru 6" dia, at the Ammco plant at Isle of Palms outside Charleston, SC.  The facility produces a powdered product used in the manufacture of polyester and required great amounts of 100% acytic acid thus the titanium piping.

If you wish more information, just PM me, and I will gladly share my knowledge.

QC Robert
robertp@westernp.com
Parent - By Lawrence (*****) Date 04-22-2011 22:50
Irv

D1.1 is a code for structural steel only, and to my knowledge has never been used for titanium..

Check out AWS D1.9

Let us know when you find out more
Up Topic Welding Industry / General Welding Discussion / Welding Titanium

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