Welding Titanium

[gwelch123]

What steps are needed to weld Titanium? I was told this statement "Titanium should be welded in a clean room environment, which we do not presently have. Any breeze, contamination or poor gas mixture will cause an undesirable coloration. Not saying it can't be done but it may prove to be difficult".

Is the above true or are there other ways without going to that extreme? The actual procedure is below




1.1 Welding Titanium
A. General

1. The corrosion resistance and mechanical properties of titanium are very sensitive to contamination. The fabricator’s proposed work area, work practices and equipment shall be subject to inspection by the Buyer before fabrication commences.
2. All tools shall be clean and dedicated to be used for titanium only. No contamination allowed.
B. Welding
1. Immediately prior to welding internal and external areas 50mm from the weld shall be cleaned by brushing with stainless steel or titanium wire brushes or buffing using abrasive or cloth. Following brushing and abrading the area shall be degreased using a non-chlorinated solvent such as ethanol, propanol or acetone.
2. The welding process to be employed shall be GTAW using AWS ER Ti-2 consumable.
3. An inert gas secondary trailing shield of high purity argon or helium shall be used during all welding. The trailing gas shall be designed to protect the solidified weld metal and associated HAZ until the temperature falls bellow 400o C.
4. Butt welds shall have an inert gas back purge to protect the root side of the welds and HAZ. This shall be maintained during tack welds, the root run and all subsequent passes until the weld is complete and cooled below 400o C. Maximum interpass Temperature shall be 200oC.
C. PQR testing requirements.
1. In addition to the testing called for in ASME IX the following tests are required:
• Two macrosections shall be taken from the test specimen for each PQR. The macrosections shall be ground, polished and examined for penetration and fusion at the root and freedom from significant defects.
• Test specimens shall be subject to a 10Kg Vickers hardness survey. A minimum of three transverses shall be made across the weld cross section with measurements in the weld metal and both HAS’s during each traverse. No hardness level in the weld shall exceed by more than 20 points the average hardness of the adjacent parent metal.
D. NON DESTRUCTIVE INSPECTION (NDE)
1. Titanium welds shall be 100% visual examined for contamination and colouration in as welded condition. Weldements shall not be ground , brushed or dressed in any way that removes surface colouration before inspection.
2. The surface of the weld, HAZ and adjacent material shall not show any colouration darker than light straw.
3. All pressure containing butt welds shall be 100% examined by radiography (RT)
4. All welds shall be 100% examined by dye penetrant inspection method (DPI). Any cracks, lack of fusion (penetration), porosity on the root or cap surface, are not acceptable.

 

[vesselfab]

"Titanium should be welded in a clean room environment"

HOW ABOUT Sometimes

"Any breeze, contamination or poor gas mixture will cause an undesirable coloration."

yes this is true


"Not saying it can't be done but it may prove to be difficult"

Not all that difficult
We have built wind screens around welding area.
have a helper holding a trailing gas shield.

 

[metengr]

Go here and research the necessary information for welding Ti. Good information

http://www.timet.com/Index2_content.html

 

[amexhts]

Titanium can be explosively welded especially in tubejoint type configurations. It can be welded to almost any other metal with this process. It is interesting since it does not exibit the characteristic wavy interface usually found in explosive welding (bonding).

 

[unclesyd]

Aside from having all the amenities for welding the most important variable is the welder. Not all welders can weld Titanium for various reasons. We had 21 of our welders + about 20 from a maintenance contractor that we screened for welding Titanium. From about 40 welders we got 5,one female, that showed proficiency in the welding Titanium. It is not that all welders can't handle the arc its has to do with their demeanor when welding. In short they will go by the book. It maybe coincidence but all the ones selected also were very proficient in welding Nickel alloys and always a pretty Tig weld.
A little money up front for fining suitable welders and getting good equipment will pay off in spades.

 

[EdStainless]

You do need to be manic about cleanliness. Your solvents must be very fresh and always stored in sealed containers. Your purge gasses need to be pure. We have always worked from liquid Ar and high purity He. We use not rubber or plastic hoses in handling the gasses. The permeability is too high and you will pick up oxygen and moisture.
Syd is right, not all welders have the temperament to weld Ti. It requires a level of care that many experienced welders feel is 'beneath them'.

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Plymouth Tube

 

[Mr168]

What sort of component/what size are you actually welding? There are portable, inflatable "bubble domes" that can be used to weld components in an inert atmosphere should the application merit its use.

 

[Histogram]

The business I owned and operated was set up to only to weld reactive metals such as Titanium, Zirconium, and Molybdenum. I used a Vacuum Atmospheres hermetic welding chamber which maintained and atmosphere of Argon with less than 20-ppm O2 and 20-ppm moisture. This unit is stainless steel with ½ Lexan front with glove ports and its volume is 25 ft3 with vacuum anti chamber for transfer of parts into chamber. My main customers were Aerospace industries and the Military. If you have specific Titanium questions I would be glad to help. P.S. I am looking to sell this chamber and accessories which is a turnkey system for welding Titanium and reactive metals; I am an engineer not a dealer.
Dave

 

[cloa]

Have you considered Keyhole TIG?

http://www.crcws.com.au/services/TIGKeyhole.htm