Out of left field....

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Has anyone, accidentally or not, used flux core or metal core filler metal with a TIG process?What happened?My major concern would be not achieving high enough temperatures on the wire to properly mix the internal doping agents.  I have the ability to electrically heat the wire to combat this.I can feed wire up to 600ipm.Thoughts, experiences and smart *** remarks welcomed.  My goal is to develop a TIG process that is capable of tolerating what would generally be considered a MIG quality joint in a production environment.  There has been a significant amount of development by the wire manufacturers to produce metal core wire that is more forgiving of less than ideal joint fit.
Reply:I think the wire needs the arc to produce gasses etc that make the metal's properties.I guess its a thought.......I wouldn't want any slag or flux in a tig weld.davidReal world weldin.  When I grow up I want to be a tig weldor.
Reply:If you want to get mig like results with a tig welder..Why not just stay with the mig??Much cheaper machine dollarwize..I know what you are typing but it makes no sence in the big picture..At least not where I'm sitting.....zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:Is this for a hot wire setup?Yup
Reply:One of the projects we did when I was in school (welding technology degree) was to break up into groups and try several "what-if" experiments. Some of the things tried were using E7018 (with and without the flux) as GTAW filler, using sub-arc flux instead of shielding gas for GMAW, using flux-core wire for GTAW, and using metal-core wire for GTAW.The group I was in did the metal-core wire with GTAW experiment. I welded a 1G V-groove with backing, 3/8" A36 plate test piece using ESAB E80C-D2 0.045" "Corweld" wire (manually fed), that was subjected to 2 face bends, 2 root bends, a tensile pull and a micro-etch.All bends passed with no visible defects or discontinuities. The tensile pull failed in the base metal (well away from the HAZ). The micro-etch showed a completely homogeneous weld with slightly higher amounts of included silicon (not silica, not silicone) inclusions than when using conventional GTAW filler, but not high enough to significantly affect the soundness of the weld. Mechanically and metallurgically, there were no issues with using the metal-cored wire.However, the fume and smoke created by the would slowly contaminate the tungsten to the pint of requiring a re-grind every 10-15 minutes. Furthermore, the large amount of silica (not silicon, not silicone) deposits necessitated cleaning of the welds between passes (not usually required for conventional GTAW fillers).As far, as using flux-core for GTAW, I did not see all of the data from that experiment, but I do recall that those welds also passed bend tests, the tensile pull, and micro-etch. However, that group did say that their tungsten required a re-grind ever couple of minutes at least. Originally Posted by Chris weldsMy major concern would be not achieving high enough temperatures on the wire to properly mix the internal doping agents.
Reply:Zapster:  No clearance for a MIG gun, otherwise there would be no question about it.Burnit:  I hope not, though I could use HWP if necessary.Tensaiteki:  Awesome information, thank you.  Just what I was looking for.  I am certainly going to try it out.  Replacing the tungsten after each weld is perfectly acceptable.  Estimated weld time of 5 - 15 min continuous per part.  It's a single layer overlay application so the silica deposits are a concern.I'll let you know how it goes.Thanks again all.
Reply:Not what you're asking about, but along the same lines, a flux cored TIG filler for backside protection without purging.http://www.kobelco.co.jp/english/wel...s/v4n2,5-6.pdfI assume you are talking about a mechanize/automated weld.  I wonder how much the filler/flux/metal core chemistry would really help in welding "less than ideal joint fit"?  I know ER70S-2 is much less fluid and faster freezing than ER70S-6, is this the kind of added control you are thinking about?  It seems like adapting to poor fitup is more a function of changing the heat source, like torch manipulation/weaving, and current adjustment.When I think of automated welding and a less than ideal joint fit, I think of a joint that in not uniform, where the gap and/or thickness varies, or maybe a joint that is fairly uniform, but has too much gap or too much difference in thickness.  It is tough to get a uniform weld with any mechanised process when the fitup is not good, mainly because one set of parameters cannot work with various joint conditions.The human can compensate for irregular joint conditions and make many subtle adjustments in torch movement, wire feeding, and current control that a machine cannot.  I believe there are people working on adaptive control with laser seam tracking where the machine adusts on the fly to changing conditions seen by the laser.
Reply:Originally Posted by Chris weldsZapster:  No clearance for a MIG gun, otherwise there would be no question about it..
Reply:Thanks for the thoughts pulser.  I have a maximum of 2" of clearance in the plane perpendicular to the weld plane.  That is not a problem, I am quite comfortable with physically positioning the torch and manipulating it in this application.Again you are correct on this being an automated process, but joint fit is a separate issue / application.  That was more of a musing than a problem in need of solving.The most common joint fit problem I see in automated process is poor rolling or a bow in sheared edges.  I think I will spend some time with something along the lines of ER70S-2 to see if it really could accommodate some of the most common problems.Of course the more appropriate solution would be to adjust the prior manufacturing processes or make other adjustments to the welding process...BUT that is not always practical.  Anything to make the automated process more tolerant is a plus I think.
Reply:Time sure does fly when you're having fun.  Not the best results, but this definitely shows possibility.  The flux core was unacceptable for innumerable reasons.  Not too bad with metal core though.  Next I'll try hotwire and see how that lays down.  This is 304sst 2" sch40  pipe. Attached Images
Reply:Where there is a will there is a way..Looks good from my seat.....zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:Thanks Zapster, I do agree that MIG would be all around easier but I've been tasked with exploring this...So off I go!
Reply:I'll try the metal core.  I have some and its the balls.  Expen$ive though.Real world weldin.  When I grow up I want to be a tig weldor.
Reply:Take a look at Lincoln's STT process as it sure sounds a lot like what you are describing. I don't know if it's been adapted to automated work or not. There are automated tig units out there using automatic wire feed. They look like a weird looking mig, lol.The difference between art and craft is the quality of the workmanship. I am an artist.
Reply:The SST is a nice package, though this part of the project is strictly investigating the TIG process.  I do use an automated TIG system and was feeding 0.045" wire at ~60 ipm with a surface speed of ~9 ipm.