TIG welding 0.500" Titanium

By Kix

Date 02-11-2008 16:29

Heat input and interpass temps will be critical as well. Is this going to be a CJP (Complete Joint penetration) seam? Can you flip this block around and weld it from both sides? If so a narrow double bevel on both sides might be a good way to go to control distortion better.

By Lawrence (*****)

Date 02-11-2008 17:59

Porosity is the least of your problems :)

That is a big weld and is really outside of standard practices for groove welding Ti in regular atmosphere... Even with special trailing shields you are going to be running into heat tint/Alpha case problems unless you really keep your heat input down, and that would mean an excessive number of fill passes. I would not be confident with this unless you have vast experience in Ti engineering practices. Semi Auto GTAW with synchronized pulsation is another notion but not really practical for one time projects.

A purge chamber would be best for such a large job. But you are still going to have huge distortion differences with GTAW compared to EB.

If it's a one time job.. You might just be better off farming the thing out for EB....

By ssbn727 (*****)

Date 02-12-2008 12:53

Hey Zeek!

I got these recommendations from the book: "Titanium: A Technical Guide" written by Matthew J. Donachie...
They are from table 9.2 on page 72:
1.) (Single "U" groove butt joint) for thicknesses starting from 6.350mm up to 19.050mm (0.250" up to 0.750") - Root Opening: 0 to 2.54mm (0 to 0.10")
Groove Angle: 15 to 30 degrees for each member (60 degree included) - Weld bead width: 2.54mm to 6.35mm (0.10" to 0.250")

I believe that the thickness of the joint you're attempting to weld is probably (Disclaimer:I say this without knowing the specifics of the joint configuration and other factors involved so, I may be guessing a bit here!) best suited for the single U groove butt joint because the thickness being 0.500" is right in the middle between the lower and upper limits of the recommended joint thicknesses compared to that of a double V, or a double U groove butt joint... For example: A double V groove butt joint has an upper limit thickness of 0.500" so the potential for distortion, a wider HAZ, and other negative results will more than likely come into play because of the process choice that has a lower energy density concentrated towards the joint when compared to that of EBW... PAW could be used as an alternative but, this process requires purchasing of equipment that would drive up the cost compared to GTAW.

Larry mentioned the possibility of farming out the job to folks that have the capacity to EBW the joint in question which would probably be a better option if precision, and the avoidance of distortion is of paramount concern... However, have you considered farming it out to be welded by PAW??? The reason I mentioned this is because it probably would be less expensive and with the use of filler metal to weld the joint, one could produce a weldment with very little distortion when compared to GTAW which in the case of the thickness being used,would require at least three passes to complete, and that's dependent to how much reinforcement is required... PAW would only require a maximum of two passes!!!

Now I don't know of any specific job shops that have lasers powerful enough for the thickness you're joining yet, I'm sure that these days there probably are... If you can find one, then that would be your second best alternative if precision is critical. However, purchasing a LBW system is typically of greater expense than that of a EBW system... It's also a better high energy density process to use compared to EBW because, it's not limited to the constraints of the chamber that's required with EBW.
Anywho, here's the link that takes you to the book for viewing the above mentioned suggestions along with much more invaluable information that involves Titanium welding such as filler metal recommendations, welding metallurgy, stress relieving and heat treatment, recommended cleaning procedures, etc.

http://books.google.com/books?id=HgzukknbNGAC&pg=PA75&dq=titanium+welding&lr=&sig=Ku1jPOCxjpTOI4EMPq7YpaZ_0vA#PPA72,M1

Note: Scroll to page 72 (Table 9.2) for the typical joint dimensions chart, and also look at page 73, Table 9.3 which gives you "Suggested welding procedure schedules for Gas Tungsten Arc Welding of Titanium" (remember to go 20% lower for the suggested current range for your application-refer to the notes in the chart!) Also look at page 73 for figures 9.9 & 9.10 in order ot decide which method of shielding and backing or trailing shield protection would more suitable for your application, or you can combine the two for greater protection from the atmosphere but, remember to control both shielding & trailing gas flow rates in order to avoid turbulence which could draw in some of the surrounding atmosphere into the fusion zone or in the trailing shield!!! Outer Chamber welding considerations, the use of collapsible plastic chambers and necessary precautions when using them... Shielding gases for fusion welding of Ti is something I would suggest to read because of the specifics covered with respect to purity grade, and dew point and shielding gas options such as a argon/ helium mix for thicker Ti members... Stress relieving is also covered somewhat on page 73 and in chapter 11 with additional info... In fact I would suggest to read pages (Chapter 9: Joining technology and practice) 65 to page 78. I would then venture into Chapter 10 which covers the machining (Joint preparation) of Ti and it's alloys... Cleaning and finishing are in chapter 11... Chapter twelve covers the relationships among structure, processing and properties... Chapter covers Corrosion Resistance... I would also strongly suggest chapter 8 which covers heat treating Ti and it's alloys. Finally, I would also suggest to your company to purchase the book as a necessary investment!!! ASM International publishes the book so, you know the info is correct - right larry? :) :) :) Btw, How's this for some thick Titanium weldments???(No chamber required)
http://www.tifab.com/subpages/products_city_tug.htm

This one was built for the International space Station (No chamber required):
http://www.tifab.com/subpages/products_nasa.htm

Here's an article that may or may not be of interest to anyone:
http://www.mines.edu/~pmendez/Publications/Papers/2000spain.pdf

One can also order this book on Titanium welding from TIG (Titanium Information Group) of the UK for just under thirty British pounds which is considered a bargain or join the group for a much more expensive price!!! So that's all for now!!! If you have anymore questions - let us know :) :) :)

http://www.titaniuminfogroup.co.uk/images/Design_guides/welding_order_form_2008.pdf

Respectfully,
Henry

By 803056

Date 02-12-2008 15:57

I've worked on projects similar to what you are thinking of.

I suggest welding it in a chamber as well, but we made our chambers using clear plastic sheeting. We fixtured the parts and built a wire frame using some TIG wire. The plastic was stretched over the wire frame and purged with argon. Depending on the size of the chamber, the purge times can become lengthy. Assume the minimum purge must displace the volume of the chamber six times. You should have a small hole near the top of the chamber to allow the "air" to excape while the chamber is purged. Argon is heavier than air, so it will push the air to the top of the chamber. Do not over inflate the chamber or you will blow the seal around the bottom of the chamber. Your seal will be the duct tape used to secure the bottom edge of the plastic sheeting to the work bench.

We used wooden sticks taped to the torch handle to extend the torch to the outside of the chamber. The filler metal was pushed through the plastic sheet and fed into the puddle as needed. The welder will not be able to position his head as close to the work as he may normally, so it might take a little practice to get used to.

Make sure you initiate an arc on a scrap piece of material to check the color of the bead to verify the oxygen and nitrogen have been displaced and you get a nice silver weld. If you don't get a silver weld, check for leakage and continue purging until the sample weld is silver.

The last word of advice is to clean and reclean the work space and the material. I assume you know how to preclean the material before welding it.

Good luck.

Best regards - Al

By SCweld

Date 02-12-2008 19:15

We have used a parts washer converted for argon atmosphere. Put some tig gloves over the rubber insert gloves. It worked well!

By ssbn727 (*****)

Date 02-12-2008 19:18 Edited 02-12-2008 19:55

Hi Al!

One doesn't need a chamber to produce high quality, contamination free weld deposits... When I used to work for Ti Fab Corp in Fairfield, NJ, only the real small stuff was welded in a chamber, and only because the size of the trailing shields were too big for the assemblies to be welded out of chamber so to speak ;)

However if all of the precautions are followed to the letter, one can produce RT/UT quality, correct weld color, and correct heat input - welds with virtually no distortion and contaminant free!!! Oh yeah ,and without any porosity :) :) :)

The rather large all Ti vessel in the picture loaded on a barge on it's way to Texas shown in New York harbor with the backdrop of the World Trade Center, was welded without any chambers at all!!! Just proper machining, cleaning methods, proper restraint, filler wire size, correct shielding & trailing gas quality, and protection, welding parameters and technique is all that was needed in order to produce the same quality weld deposits found when one uses a chamber without the added restriction of using a removable plastic chamber :) :) :)

The one aspect of this project of Zeek's that I'd like to know more about would be the sizes for rest of the dimensions that make up the members of this joint, and the actual grade of Ti... It would definitely answer some of the questions I have ;) How about it Zeek???

P.S. now I'm not 100% positive but I believe the submarines in the pics below are the dreaded Ex-Soviet Alpha class boats that have Titanium welded hulls and if I remember correctly, the hull sections were welded in these giant chambers which made the costs of constructing these vessels very, very expensive!!! However, they could definitely outrun and out dive their American counterparts except for one caveat: These subs couldn't outrun the torpedoes, and they were sooo darn noisy that one did'nt need to be as fast or dive as deep when all one had to do was to listen to their sound signature and BOOM!!! They would've been history!!! I wonder if this ever happened in the sometimes not so "Cold war"??? Hmmm ;) Maybe that's why they stopped making them only after a few copies instead of the excuse told that the powerplants were problematic!!! Hmmmm ;)

Respectfully,
Henry

By DannyM Date 02-12-2008 21:37

Hi Zeek,

I have been working with Titanium,Zirconium,Hastaloy and oteh exotic metals for the past 15years. I am certified high pressure in all of these metals and many more. You DO NOT need a chamber to weld your piece. A good purge and trailing sheild will be more than enough. Make sure that your flow meters are set properly to avoid turbulance. You should not be worried about porosity if your Ti. is cleaned properly with acetone and a S.S. wire brush. A double bevel " V " groove is fine with a 3/32" root opening. If you are worried about distortion weld on one side of the joint and then flip it over and do the other side and then repeat.

Danny

By 803056

Date 02-13-2008 05:13

I agree that you don't need a chamber, but if the part can be chambered, it ensures the proper inert environment.

I've fabricated trailing gas cups from stainless sheet metal, but you have to be very careful not to contaminate the weld with air. Someone opening a door, too fast on the travel speed, someone turns on a fan, you name it, it will happen. Murphy at work and play.

I liken it to; "You don't need brakes to drive a car, but they sure helps when you need to stop!"

How are you doing Henry?

Best regards - Al

By ssbn727 (*****)

Date 02-13-2008 08:01

Hi Al!

I agree that if you overlook the fact that "Murphy's" all around us, Murphy will come to play!!! that's why one has to consider all of the likely scenario's mentioned, and even some not mentioned... However, if one knows how to prepare for welding Ti without a chamber, the job will turn out just fine!!! My only question left for Zeek would be to know what are overall dimensions to the weldment in question??? Knowing this also is a very important factor in deciding whether or not to chamber the joint ;) Whew!!! That sounded too close to someone describing a method of smoking the infamous "Loco weed!!!" I gave that up many, many moons ago, and I don't recommend it to anyone that needs to use their brain in any capacity especially on the job!!!

I guess I'm doing better Al ;) I can wear my regular glasses again, and my diabetes has virtually become as close to a phase as I could've hoped for - if you catch my drift so, I believe I'm batting 1000 in the health department... The big "C" has gone into hiding also lately so I'm feeling stronger as far as that is concerned... I've got six weeks left teaching SMAW & GTAW at a Combined Cycle HRSG LNG power plant which has kept me somewhat busy since November so, it helps ;)

Overall, my health is improving slowly but surely so, I really can't complain much these days except for the taste of food with the meds I'm taking!!! I mean wow!!! Sometimes I have a real hard time tasting the ingredients as opposed to what the meds trick me into thinking what the food tastes like - which usually taste horrible!!! The tough part is that my choices of food are really limited to the amount of sugar or "sugar alcohols" that are present in the ingredients, so I usually have to stick with "rabbit" food :( I'm thinking of investing in toilet paper stock since I use so much of it these days... Maybe I'll get a discount on some boxes being a shareholder :) :) :) Yeah RIGHT!!!

But heck!!! If that's all I've got to concern myself with, then I'm greatful to be in better health despite of the shortcomings I'm learning to accept :) :) :) Thanks for asking!!!
BTW, how are things with you Al???

Respectfully,
Henry

By darren

Date 02-13-2008 11:41

i was missing your input henry, glad to hear your feeling better.
cwi55 is building a miniature rc sub. is there any way that a signal can be transmitted to the sub without a tether. if you don't know i doubt that anyone would. even though its not my project i found it interesting and i was thinking that it seems a substantial barrier to cross. sound would have a chance at use but hard to encode and even harder to encrypt electronic signals would seem out of the question as would emr.
whats your take?
darren
all i know about Ti is its on the periodic table, thats why i following the thread. something new to learn.

By 803056

Date 02-13-2008 14:28

Glad to hear you are doing better and you sound like you are in good spirits.

I'm still running trying to stay ahead of the wolves.

I bought a KB USM 35X UT machine. I considered the Epoch XT, but I didn't care for the form factor and maybe I dumb, but I didn't care for the logic of their menus.

I had both machines over the weekend to play with. I tried to calibrate both machines as if they were old analog machines, i.e., ignoring the setups the sales rep had installed. When all was said an done I had a job to do on Monday and I felt most comfortable with the KB. That's the machine I purchased and I'm happy with it. There's a few tweaks I would prefer, but it does everything I need to do.

Work wise I'm busy. I have to go up to Toronto to help some fellas tweak their aluminum pipe welding techniques. I'll be there for several days and then I head down to Georgia to work with some welders on copper nickel and aluminum pipe for about a week or so. Back to New England for some NAVSEA TP248/278 piping work. The motto "Have bags, will travel", fits the life style of a consultant. Life is never dull or boring and suits my nature. I hate working on any one project for too long a time. Even as a welder, I would get bored if I stayed with any one project for too long a period. I guess that's why I never cared for the nuke projects. With the consulting business I usually have several projects going at any one time so I don't have time to get bored.

I'm teaching a metallurgy class for the AWS section this weekend. It looks like there will be a good turn-out and it should raise a few dollars to help pay for the monthly meeting notices we send out. As a matter of fact, I have to get the material to the printer this morning so we'll have something to hand out at the seminar. So I better cut this short.

I heard from Stephan. He's buried in his work, traveling all the time and gets home only on the weekends. For a family man, that will get old real fast. He said to wish everyone his best.

Best regards - Al