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The GTA weld pool, and the arc plasma in a totally inert atmosphere does indeed behave differently than being surrounded by air, but I think your point regarding the length of the tungsten vs the diameter is a valid one. ;) the only problem is to explain how the weld pool was so darn hot enough to "swirl" the tungsten droplet and maintain the temperaturehot enough within the pool to actually "smear" the tungsten in such a manner when we all know that W has a significantly higher melting temperature than whatever it was that Mike was welding inside the chamber...
What bothers me most about this thread is that the OP expects us to give a comprehensive answer to his query without providing us with
ALL of the necessary information we need in order to give the OP as comprehensive an answer as possible!!! :( :( :( So how about giving us
ALL of the relevant information that you can muster together Mike, and then we can give you a better informed group of probabilities, or reasoning as to what your superiors are calling "Tungsten Smear"???
I mean, even if you did provide a picture of the RT film, without saying what the thickness of the Aluminum? Or the actual geometry of the "business end" of the tungsten, the diameter of the tungsten... Was it a casting or not (you mention a casting in one of your later posts,but you're not being specific enough in one post and instead, are just feeding us little bits of data as this thread grows longer and longer!). Was the shielding gas 100% argon, or were you using an argon/helium mix for more penetration (this could be really important as to how the weld pool was hot enough to enable the tungsten droplet(s) to "swirl" around in a very hot molten pool)... Also, how oxidized was the Aluminum casting, was the thickness of the Aluminum surface oxide layer greater than normal???
So if you have anymore information to share with us Mike, now would be the time to do so if you want to receive a pretty good explanation as to why your superiors, and specifically the metallurgist is calling these indications as "tungsten smear." Without
ALL of the pieces to the puzzle revealed, the only thing you will get is a bunch of different opinions based on conjecture and incomplete speculation on the same level junk bond traders sell their own wears in the stock market!!! :( :( :(
I mean no disrespect when write this, but if you want us to help in figuring this out for you, then you need to give us
ALL of the information available including data which you may not even think is relevant - CAPECHE??? :) :) ;)
Now if they are insisting on using pure W for welding Aluminum, then the metallurgist is either a dinosaur with no understanding that zirconiated W as Larry mentioned earlier, is far superior than pure W for use with Aluminum AC GTAW, or the company is too set in their ways to "weldcome" any change for the better when it comes to solving a problem they claim is actually cutting into their own profits which gives them justification for denying the welders a raise!!! Yet in reality, it is their own ignorance as the real reason why this is happening in the first place!!! There!!! I finished with my rant!!! :) :) ;)
I do hope that it turns out that the fault lies in your company's own "horse blinders" mentality for not being open to changing the type of W they're using to perform these welds!
Respectfully,
Henry
Respectfully,
Henry