Need Help Welding Tungsten

By - Date 07-02-2004 22:33

Hello, I'm new to this board and am looking for somebody with experience in welding Tungsten parts with a heli-arc setup. The company I work for closed down our branch out on the east coast and brought it out to the west coast to continue operations. The problem is that we lost our experienced welder and are on a pretty steep learning curve. We are welding tungsten heating elements but the welds are coming out extremely ugly and do not look like they are structurally sound. I'm after any techniques, tips, tricks, or any tidbits of information on how to get a good solid weld on tungsten parts that will be structurally sound. Right now the welds almost look like they are cold welds. There is a guy by the name of Bud who used to work at our company and is a member of the American Welding Society, so if you're out there Bud, please reply! Thanks for any help!

Paul

By campro Date 07-03-2004 18:41

there is a man on the web called mr. TIG i dont remember what the web site is but if you search for TIG you will find it and you can ask him how to do it.

By pgeweldor (*)

Date 07-04-2004 01:57

Hi, I think it's WWW.TIG DEPOT.COM. Hope it helps. Paul

By Scott_V Date 07-08-2004 15:50

Tungsten welding with the gas shielding processes is accomplished in an inert gas chamber or dry box. Welding is done in the pure inert atmosphere with normally good results. The filler metal compositions should be the same as the base metal. The base metal in the heat-affected zone becomes embrittled by grain growth and recrystallization as a result of the welding temperatures. Recrystallization raises the transition temperature so that tungsten welds tend to be brittle. Tungsten is highly notch-sensitive, craters and notch effects such as undercutting must be avoided. The gas tungsten arc welding process is used with direct current electrode (negative). Welding should be done slowly to avoid cracking. Preheating may assist in reducing cracking but must be done in the inert gas atmosphere.

pulled and edited from:
http://www.key-to-metals.com

By - Date 07-08-2004 17:04

"Welded joints are very notch sensitive, and where possible, the weld surface should be finished smooth and faired gradually into the base metal."

What exactly do you mean by "notch sensitive"? I have heard this from two people now but I'm not exactly sure what it means.

By swnorris (****)

Date 07-09-2004 17:39

Hi Paul,

Please see my second post in the technical forum. In short, notch sensitive means that tensile stresses applied along a small inside radius of curvature has a propensity to produce cracks, hence the need to smooth out welds and carefully blend the weld toes to the base metal. The slightest bit of undercut at the weld toes constitutes a notch potential. It is the nature of the material to not have notches where stress levels will cause cracks.