Fusion Confusion

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I have read many posts that say something to the effect that you should use filler rod in TIG for everything except stainless steel which you didnt need to cause it fuses fine without it , because the weld joint will crack.   My question is .. we use TIG and create a molden pool of steel .. then we add ...   steel filler...  and that wont crack ..   so what is it about the fillerbeing added that is so different ... in the end its all steel ..  I'm sure its a metalurgy thing .. but would like to understand .. Could there be more added to the steel filler rod then just steel?Randy - N2CUALast edited by Lanmanb4; 08-27-2006 at 10:36 AM.
Reply:i think it has something to do with how much shrinkage carbon steel has and the rate at witch it coolsChuckASME Pressure Vessel welder
Reply:Originally Posted by Lanmanb4I have read many posts that say something to the effect that you should use filler rod in TIG for everything except stainless steel , because the weld joint will crack.   My question is .. we use TIG and create a molden pool of steel .. then we add ...   steel filler...  and that wont crack ..   so what is it about the fillerbeing added that is so different ... in the end its all steel ..  I'm sure its a metalurgy thing .. but would like to understand .. Could there be more added to the steel filler rod then just steel?Randy - N2CUA
Reply:I didnt mean to say that you shouldnt use it with stainless ... only that you didnt have too ...  Sorry for the bad wording .. But I still dont understand why just adding more steel filler will keep it from coming apart ..Lanmanb4 thinks lurk mode might be safer .. LOL
Reply:I have wondered the same thing, Lanman.  Lots of stainless welds are done without filler at all.  I think maybe it has to do with the fact that many of these welds are not structural, like for example, stainless restaurant equipment and involves mostly thin sheet stock.  In those situations, the emphasis is probably more on the desire to keep the welds as smooth and contamination-free as possible for sanitary purposes and post-weld cleanup.  On thicker material or in situations that are more structural, filler is probably required.  According to Zap, on regular low-carbon steel, the (un-filled) puddle doesn't flow as easily as it does with stainless.  I actually didn't know this until Zap said it in an earlier thread that you could not fuse low-carbon steel effectively without filler, but then again, I never had a reason to try it.  Obviously, if this is the case, there must be some metalurgical reasons, and maybe these same metalurgical characteristics are behind the fact that stainless is more often done without filler.  Heck, I guess this is a long post for simply saying "I don't know either", isn't it?!?!Last edited by smithboy; 08-27-2006 at 11:27 AM.Smithboy...if it ain't broke, you ain't tryin'.
Reply:Welding wires although they are solid are made of a particular alloy that aids in fluxing actions.Two elements, among others, that are added to steel welding wire are aluminum and silicon.  These trace amounts capture any iron oxide in the molten pool and the result is silicon oxide and aluminum oxide which floats to the surface.  That is the glass you see on some steel MIG welds.  Fluxes on coated electrodes ( smaw) add to the alloy, clean the molten pool, keep the atmosphere away, control cooling and even shape the cooling pool.   Solid wire can't do all those things but darn near.
Reply:As an afterthought:  Try TIG welding with gas welding rod intended for oxy -acetylene then go back to TIG rod.  You will see a significant difference.  It especially is evident as you finish off the weld with gas rod and see an eruption of dissolved gasses/crap at the end of your bead.
Reply:Originally Posted by lotechmanWelding wires although they are solid are made of a particular alloy that aids in fluxing actions.Two elements, among others, that are added to steel welding wire are aluminum and silicon.  These trace amounts capture any iron oxide in the molten pool and the result is silicon oxide and aluminum oxide which floats to the surface.  That is the glass you see on some steel MIG welds.  Fluxes on coated electrodes ( smaw) add to the alloy, clean the molten pool, keep the atmosphere away, control cooling and even shape the cooling pool.   Solid wire can't do all those things but darn near.
Reply:Thanks for that great explaination .. I am using ER70S-3 and ER70S-6For my TIG ... is that ok? Its just listed as filler metal on welding depots site.. doesnt say TIG or OA ...
Reply:I use 70S-2 wire for all my steel work with tig..what you have is wire correct?  ...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:I dunno .. I should send an email to welding depot and ask I guess?
Reply:Originally Posted by Lanmanb4I dunno .. I should send an email to welding depot and ask I guess?
Reply:Originally Posted by zapsternowhat do you have for filler?does it have a flux on the outside?tig filler wire is just that..36"long with 1/16...3/32..1/8 sizes that look like a piece of wire..but straight...no coating of any kind ...zap!
Reply:I went back thru what filler rod I had ordered .. and I had ordered both the -2 and the -6  .. I might go play and try to see the difference in how they weld .. if -6 works for MIG with ARGON gas .. seems it would work for TIG? ( assuming there ) ... but the question is .. how well ...
Reply:This is getting more interesting by the minute ... *DISCLAIMER*Its early and I'm not an early morning person .. have apnea .. so I have to get up a couple times a nite .. so bear with me if I word this poorly .. ok .. I looked up the composition for ER70S-6 and its fine for TIG according to the Lincoln and weldingdepot weldsite.   Contains Manganese and Copper.   ER70S-2 is , so it seems even better suited for TIG .. Especially for overhead welding .. and so I would assume vertical welds as well .. making me think its better over all .. Says it freezes quicker than -6.  Which might explain someones comment about one of your welds looking "cold" when it wasnt there Zap .. My thinking is that if it freezes faster then the "dime" look would be more pronounced . The compostion for the -2 is different ..Something happened...  Since early last week, I started having trouble with my welds ... wasnt surewhy and was getting frustrated .. hmmm well .. seems I bought some Lincoln R45 welding wire... and it is for OA , not TIG .. and was using that .. I guess that could explain the problems I was having ?I unfortunately mixed them with my -6 wire .. so will have to get out the glasses and sort them out ..  not sure what I'm gonna do with the OA wire...Wind it into different stick figures ..  :LOL:Welding Depot  lists ER70S-6 for GMAW and GTAW.  And to add to the fun .. there is also a ER70S-3This is such fun ..
Reply:Correct me if I am wrong but I don't believe TIG and GMAW wire are different.  They have same AWS code numbers.  You can uncoil a spool of wire of purchase the straight stuff.
Reply:When I got my first tig welder (Powcon 300 ST) back in the early 90's I had never actually tig welded before and knew very little about it in general.  I basically had watched some people do it and had the general idea down, that was about it.  Anyway, I had been OA welding some, and had a 5lb box of 1/16 OA mild steel filler rod.  Not knowing there was a difference, I tried to use the OA rod with the tig welder - and was getting very frustrated!  I had a ton of porosity in my welds.  But, I kept playing with it and eventually got to where I could do a decent job.  I then had an idea and tried uncoiling wire from my mig welder.  It was .035, so it was too small, but it welded MUCH nicer...  So, after a visit to the local welding supply and my guess was confirmed - there definitely is a difference!  They hooked me up with some ER 70s2 and what a difference!
Reply:Thanks Panozeng ... I feel better knowing I wasnt the only one that did that ..