The Armour Archive

Any suggestions on processes to keep the heat affected zone from becoming brittle when welding Ti? I have made a few attemptes to weld .040 Ti with my Tig unsuccessfully. Fusing can be broken apart down the center with my fingers and using slivers as filler merely causes it to shatter next to the weld. The welds look fine, perhaps with Argon I am using the wrong sheilding gas? Is there a means to heat treat afterwards? Thank you fro any suggestions.
Cheers, Erick D.

Are you using a neutral gas on the backside of the weld? If not you’re probably contaminating the weld on the backside.

Check this site: http://www.tigdepot.com/titanium_welding.html

What exactly are you welding together?

I am doing simple two piece knee cops with the ridge down the center. I tried to form them deep enough in one piece as I do other materials, hot and cold without succcess. Stress cracks and work hardening, thought I could cheat. I do not have the weld area purged from the backside, and I am getting a white powder in the heat zone.
Cheers, Erick D.

You might want to talk to Mrks who posts on this board. He makes Ti armour. I have not seen him for awhile so I don't know if he has had time to be on the Archive. His website is http://communities.msn.at/ScaMachineArmorors/_whatsnew.msnw

Good luck
Martin

hi there
I have been pretty busy so havent posted much lately.

I will post pics of my new personal 16th centry sport suit suit when it is finished. the breast plate weighs 5lbs.

I do almost all my work cold with huge machines. a little hot hammerwork now and then but it is much more work than having good patterns and using the machines.

years ago I looked into tig and yes mig welding. the mig wire costs over $100 a pound so I have never bothered with it. then there is the alloy problem. are you using the correct alloy as filler wire? it also needs to be done in an argon box. I visited a bicycle manufacturer during that time of discovery. he used a tig in an argon box and the welds were beautiful.

Ti absorbs hydrogen like a sponge when heated over 450F the hotter it is the faster it absorbs so it should stay out of a gas forge. I did some hot work with a forge and the results were similiar to what has happened to your work. a few heats were ok but then the piece started getting wealk. you can work it with propane but only get about three strikes because it does not hold heat.

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mrks
squire to sir aveloc
tiarmour.com ==>> maker of fine Titanium armour

[This message has been edited by mrks (edited 05-14-2003).]

ok a little more research onthe mr tig site. you need to build a prurge chamber. I have a vacume box for welding and grinding but you need the opposite.

I actually started to aquire the materials for Ti welding but decided it wasnt worth the trouble and adjusted my patterns. I still have an argon tanks and a few other bits and pieces saved for future use.

the below from the mrtig website: http://www.tigdepot.com/products/p9.html


"Mister TIGâ„¢ " says: "Most purging is done with Argon, which is heavier than air, so maintaining a positive pressure inside the chamber ensures your weld is adequately covered."



When your needs require a completely inert environment, purge chambers provide a safe method of protecting Titanium and other refractory alloys. Hook up your inert gas to the inlet, feed your torch through, place your parts inside, and purge the air by adding gas. Air then purges through the top. Once you have a good inert environment, create a test weld to make sure.
DO NOT turn off the gas when you're ready to weld. Keep positive pressure inside the chamber while welding.
TIG-24TLPC-S $1,950.00
Qty




The Hi-Tech Inflatable Purge Chamber (30" diameter as shown) is used in the TIG process to provide an inert atmosphere for welding Titanium and other reactive alloys. Unique to this design is the ability to draw a vacuum around the product to be welded which collapses the chamber, removing atmosphere. The chamber is then filled through a perforated hose that covers the circumference of the chamber. This filling process allows the inert gases to diffuse more efficiently and purge out atmospheric gases faster than traditional filling methods. This process significantly reduces the time required to reach an inert atmosphere suitable for welding.



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mrks
squire to sir aveloc
tiarmour.com ==>> maker of fine Titanium armour

hehe

boy welding Ti is expensive. there is little information about titanium. it is almost an industrial secret. the few who know about it do not usually share the information. mr tig is very generous with his information. here is one of his product descriptions that solves or at least diagnoses your problem....

from mr tig: Titanium weld color inspection kit: http://www.tigdepot.com/products/p7.html

Weld color inspection is typically used to determine if contamination has occurred during the welding of Titanium alloys. Color gives an indeication that oxidation has occurred. A glossy silver or light straw color weld shows adequate sheilding. As the oxide layer thickens, the weld surface color progresses through a range of colors eventually to gray or white loose flakes. The inspection kit samples clearly show acceptable and unacceptable specifications. This helps the welder or inspectors correctly determine weld acceptance. No longer is the welder or inspection personnel left to ambiguous and hard to interpret written color descriptions. The inspection kit also aids in characterizing and correcting the cause of unacceptable weld contamination.

from the Model SGI-3 $4437.50
Specification of SGI-3 Weld Gas Analyzer

INTRODUCTION TO THE SGI-3 MEASUREMENT SYSTEM
Inert gas welding requires the exclusion of oxygen from the weld zone during the welding process. The shield gas (typically argon) needs to be free of oxygen from air leaks into the feed hose and the backside of the weld needs to be protected with a purge, or backing gas to ensure a low or controlled oxygen concentration on the back face of the weld. On the front face of a weld the inert gas stream (provided it is free of leaks) efficiently excludes oxygen from the weld zone. On the backside of the weld special precautions must be taken to prevent oxidation. This involves the isolation of the backside of the weld with fixtures that provide for the purging of this area with an inert atmosphere. The SGI-3 instrument works with these fixtures to continuously sample the purge gas and to monitor the oxygen concentration. Monitoring the weld gases with an SGI-3 adds a quantifiable element of quality control to the inert gas welding process. It also provides an economic benefit by giving the welder the information he needs to accurately judge the purge gas flow rate and purge period.

For more information, call at 1.800.456.9172 or send an email to mistertig@tigdepot.com. More information on this subject is also available at http://www.ewi.org/njc/articles/oct99.html

11201 $1,795.00


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mrks
squire to sir aveloc
tiarmour.com ==>> maker of fine Titanium armour

[This message has been edited by mrks (edited 05-14-2003).]

Thank you all for your replies. I suspected hydrogen embrittlment as a friend of mine who manufactures 4130 bike frames suggested. A purge box would seem simple enough to set up. I have seen some real fancy ones with a clear blown poly hood. I have had success rolling the top edge of the cuisse with heat from my oxy-acetlene, brought it up to a dull orange. You are quite right Mrks, it sheds heat amazingly. I am forming the material with a 60 ton c frame press I built with an 8 inch dump truck cylinder. Nice array of tools you have there, Mrks! Thanks again,
Cheers, Erick D.

Check with Harbor Freight for a cheap sandblasting box. With a minimal amount of work you could turn that into a argon soak box.