Could you help explain what's happening here and possibly how to avoid it

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I am welding up 1 square 11 gauge tubing using MIG and thought I had the heat dialed in just right but I end up with these holes smack in the middle of the bead.  I am guessing here but suspect that I have it a bit too hot and when I pause at the end to fill the puddle the result is almost a blow hole through.Any recommendations would be appreciated as to how to avoid this from happening.  Lives don't depend on this weld, it's a steel rack. In advance thanks!
Reply:Looks like the middle is falling out right there along that thin edge. The heat is built up by then, there is less heat sinc there, and it looks like you may be doing a drag? Turn it down a tad or move faster and or try a push if you are dragging. A push will let it cool behind the arc a little quicker. A drag keeps the arc pointed towards the bead. As a side note you could start & and finish around the corner just a bit further too. If that was a little larger tube you could weld from the middle both ways."The things that will destroy America are prosperity at any price, peace at any price, safety first instead of duty first, the love of soft living and the get rich quick theory of life." -Theodore Roosevelt
Reply:are you welding all the way around the tubing?
Reply:i'm curious as to the brand of wire and if this has occurred welding other pieces. the reason is on the new 211 i just bought i installed radnor brand .030 and was having the same type issue on thin tube as well as flat bar joints. the weld looked good till i stopped and then i would see a sink hole drop about 3/8" to 1/2" back from the end of the weld as it cooled. i tried different settings, speeds, push and pull, backing up at the end and nothing helped. it was happening while my son was welding with the machine also. after maybe an hour of playing with the new welder it just cleared up and hasn't done it since. the only conclusion i could come up with was that the wire had some contaminants either in or on it for the first part of the spool. same brand and size wire from a new spool i put on the new ta181i had no issues so it was only the batch on that one spool. both boxes they came in were clean and dry.225NT bobcatAEAD200LEScott 125mm175, mm252 w 30A, PT225mm211, TA 181iHyper Therm 380, cut master 529100X & XX, Digital Elite6 Victor setssmith little torch, meco midget kalamazoo band sawsteel max saw evoulution circular saw
Reply:Hello 200mphbusa, the tube may be outgassing. Try drilling holes in the tube that the other tube is terminating against hiding the hole with the tube that intersects it. It is building up internal pressure and "blowing" out through the crater where you are ending your "weld all around". Since most tubing is treated with an anti-rust coating it can have a coating of this on the inside as well, the welding heat can cause this stuff to react and cause internal pressure that can result in the types of issues that you see. Good luck and best regards, Allanaevald
Reply:judging from the look of his welds that likely isn't the problem unless he has closed the ends of the main tube.. he's not closing his corners from what i see on the intersecting tubes. correct me if i'm wrong.Last edited by jbmprods; 04-18-2012 at 03:22 AM.225NT bobcatAEAD200LEScott 125mm175, mm252 w 30A, PT225mm211, TA 181iHyper Therm 380, cut master 529100X & XX, Digital Elite6 Victor setssmith little torch, meco midget kalamazoo band sawsteel max saw evoulution circular saw
Reply:What is your gas set at? And what type of gass?  I looks to me to be porosity from lack of cover gas. Also if you have rust it will some times creat porosity like that..... Maybe...
Reply:Originally Posted by aevaldHello 200mphbusa, the tube may be outgassing. Try drilling holes in the tube that the other tube is terminating against hiding the hole with the tube that intersects it. It is building up internal pressure and "blowing" out through the crater where you are ending your "weld all around". Since most tubing is treated with an anti-rust coating it can have a coating of this on the inside as well, the welding heat can cause this stuff to react and cause internal pressure that can result in the types of issues that you see. Good luck and best regards, Allan
Reply:I really don't think its the wire.   Heat is heat.  My first thought was if it was the last weld on the tube, its blowing the hole from out gassing like said above.  Its 11 ga tubing, that means 1/8" wall so all that is neeeded is a 1/8" fillet.   That one looks like 3/8 or bigger fillet.   Too much heat.  Is that the last weld on the cross member?  If it is, then it could be blowing your weld.     Otherwise you are just plain too hot.How is the fit up?DavidLast edited by David R; 04-18-2012 at 09:53 AM.Real world weldin.  When I grow up I want to be a tig weldor.
Reply:Gentlemen as always I can't tell you how much I appreciate the input, this site definitely makes me a much better welder.  I suspect that David R is correct I am laying too big a fillet for 1/8" wall tubing.   I don't think it's my wire because I've used miles of it on the same steel and others and not experienced the problem.  It's 0.030 Lincoln Wire SupeArc L-59.  I do have the other side unwelded and there is a slight gap. The fit up is tight, meaning the parts mate up nicely.  It's only welded on three sides. I'm using for a shielding gas Argon/CO2 mix at a flow of 18 cfh.  Which is probably a problem also because Miller recommends 25 cfh for that material, wire size and metal thickness (I should have checked sooner).  Thanks for suggesting it!  I just swapped out the tank and never bothered to check the regulator.  He's my plan:--Correct the shielding gas flow rate to 25 cfh --Turn down the heat and possibly speed up a tad --Start and Finish a bit further --Try push rather than drag Again, thanks a million to each of you for the sage advice and recommendations in my book it's priceless!
Reply:I build a lot of stuff from 1/8 or 11ga tubing with welds completely around the joints. I have never had a problem with outgassing after stopping. Not to say this isnt the problem most of these guys know way more than I do. I have had a problem with to much heat blowing out thin edges. I try and ride the pool up on the more solid side helping to control the heat going into the edge metal.
Reply:0.030 Lincoln SuperArc L-59 ??I don't even see that size listed in the catalog (C1.10, dated 10/2011) or on the website (just checked).  Smallest diameter listed for L-59 is 0.035, in 44 lb spools (fiber or steel spool).0.030 Lincoln SuperArc L-56 certainly is listed.Not that it should matter all that much, as both wires are listed as ER70S-6.If it's not being caused by air blow-out from trying to weld a 'sealed' tube, I'd tend more towards you are just plain putting too much heat into the weld such that when you pause you end up melting right through things.If you are moving along as you lay down the bead (and melt into the parent material), you are moving the arc and the heat.  No problem then.But if you pause in one place for too long and the weld parameters are set on the hot/agressive side for when you are moving along, then once you pause in one place you just blow a hole right through.Also, as mentioned, for 1/8 inch wall material you just need only about a 1/8 inch bead of weld.  Too much weld and you are wasting time and material and putting too much heat into the joint.For 'small' welders, a flow rate of ~20 cfh is usually just fine.  The weld nozzle is small, the wire is small, and the amps are (relatively) small (gas flow rate also acts to cool the torch and gun cable.  Big amps means big gas flow rates for multiple reasons.  Really big amps often means needing a water-cooled torch.)  It really doesn't look like a gas flow issue (from here, over the internet, from a forum picture, etc)For solid wire (GMAW), usual general motion is to use a 'push'.  Drag is usually for slag-producing proceses (SMAW or FCAW-S).If there's slag, then drag.I think your issue here is a bit of technique and running a bit hot on the parameters.  Turn down the machine a little bit, push the puddle, watch the puddle itself, run the weld bead up to the corner and then back-track a bit to fill the crater instead of just pausing in place.Also, you mention 'three sided weld'.  So if you mean you are welding the 'top' joint and the two 'faces' of the tube rack (looks kind of like it in your first pic, seems like you welded the 'faces' first and then ground the welds flat before running the weld on the 'top' joint/seam), I'd suggest changing your weld sequence a bit.Tack things as needed/desired, then weld the joints but 'wrap' the weld bead around the corners.  Then grind the 'faces' flat as desired.  There is usually plenty of stress already going on at a corner, no good reason to put a start/stop right there as well.  That would also help in not trying to stop and do a crater fill right on the corner too, run past the corner and tie-in to the already done weld on the 'face' and burn-in a bit to the existing weld there.  That's if you can't get the motion to run a weld around the corner completely without a stop to change your position.General Best-Practice is to not put start or stops on the corners.  The best laid schemes ... Gang oft agley ...
Reply:Back off the heat and increase your travel speed. Those welds are huge you don't need them near that size. Gas coverage looks good."Liberalism is a mental disorder" Dr. Savage
Reply:Originally Posted by 200mphbusaSnip  .....I do have the other side unwelded and there is a slight gap. The fit up is tight, meaning the parts mate up nicely.  It's only welded on three sides. I'm using for a shielding gas Argon/CO2 mix at a flow of 18 cfh.  Which is probably a problem also because Miller recommends 25 cfh for that material, wire size and metal thickness (I should have checked sooner).  Thanks for suggesting it!  I just swapped out the tank and never bothered to check the regulator.  He's my plan:--Correct the shielding gas flow rate to 25 cfh --Turn down the heat and possibly speed up a tad --Start and Finish a bit further --Try push rather than drag Again, thanks a million to each of you for the sage advice and recommendations in my book it's priceless!
Reply:'outgassing' was what i was getting at, i just didnt know the correct term for it. thats really the only time i've had an issue like that. but like david r said..if theres a gap, thats not it.
Reply:its a crater crack from spot porosity, no covereage with 18 cfm
Reply:The talk of flow rates is interesting. I'm using straight CO2, with a flush, 1/2" nozzle, it's a 140A MIG. My regulator (dial-type) is for argon/CO2, so it's probably even less accurate than normal, given the gas change. But for flat welding, I have it set to 5 CFH. I did not notice a difference between 15-20 and an indicated 5, so I've left it there. This is in an enclosed garage, with no air moving around. I did try a weld with no gas, which looked very different, so my assumption is I'm getting enough coverage at 5. Should I be checking/setting this some other way? I do mean to check my actual flow rate, vs what's indicated, but haven't gotten to do that yet. Thanks.
Reply:If I were you I would go back and hit the textbooks,get more practice, or the miller gauge for fillet weld thickness, moonrise and flatbusted hit the nail on the head you are slaughtering those joints with filler, it cools and contracts.best
Reply:Just weld and have some one turn the regulator down until you get porosity.  Its easy to see.    Now you know the minimum under the conditions you are welding.DavidReal world weldin.  When I grow up I want to be a tig weldor.