Feedback FCAW-S Welding Would be Appreciated

admin

I am a building contractor and have been welding off and on for years but recently got a certifaction for up to 3/4" steel in all positions in order to do some structural welding on one of my building projects. I think I am doing ok but want feedback to optimize my technique since these welds will be inspected, possibly with x-ray or ultra sound and want to do what it takes to get it right the first time around. I am using a Miller XMT 350 CV/CV with 60 series wire feeder. This weld is prequalified (AWS specification A5.20) wire: Excel Arc 71 @ .045", gas: Ar 75%/ CO2 25% @ 14-24 LPM, Base metal A36 grade B steel, my machine settings are 23V, 215 IPM wire speed and the amp reading on the machine is about 170. This weld has a root opening of 3/8" with 30 degree groove angle and am welding in 7 passes, wire brushing between each. My contact tip to work distance is 5/8" and travel speed is about 8-12 IPM I tried 24V in practice but was getting too much undercut so went to 23 V which is at the bottom of the wire manufacturer's setting range. I had some problems with wagon tracks too in practice but that was corrected with better control on work distance and angle. I got some slag inclusion on the edges in practice with my weave patterns not being even enough but think this is under control by keeping the bead full and pausing long enough at the edges. Any tips or feedback will be appreciated. Attached are some pictures of one of my welds w/ prep, about 1/2 way through and finished product. Thanks Attached Images
Reply:Originally Posted by CsparksI am using a Miller XMT 350 CV/CV with 60 series wire feeder. This weld is prequalified (AWS specification A5.20) wire: Excel Arc 71 @ .045", gas: Ar 75%/ CO2 25% @ 14-24 LPM, Base metal A36 grade B steel, my machine settings are 23V, 215 IPM wire speed and the amp reading on the machine is about 170. This weld has a root opening of 3/8" with 30 degree groove angle and am welding in 7 passes, wire brushing between each. My contact tip to work distance is 5/8" and travel speed is about 8-12 IPM
Reply:Thank you DSW for the great feedback and tips.  I will try faster and hotter and your point about reading the puddle and working on a tighter weave is well taken.  I can see this is a great forum, getting good specific feedback right away.  Thanks again. Last edited by Csparks; 02-14-2012 at 12:24 PM.Reason: add a point
Reply:If it was me I would have a longer backing bar to start and stop my weld outside of the flange of the beam. That will ensure you don't get any porosity in your start and don't have to go back and build up your stop. Then you can always go back and cut it off flush if you want.
Reply:Haven't used that wire myself, so just going to go by your listed info and the pictures and the spec sheet (right from the Hobart site)http://www.hobartbrothers.com/upload...xcel_Arc71.pdfThat wire is spec'd as using pure CO2 as well as C25 (multi spec E71T-1C and E71T-1M, as well as E71T-9C and E71T-9M), but note in the 'fine print' on the spec sheet that (as usual) the listed parameters were done using CO2 and if using C25 you have to drop the voltage ~1V.Next, you are welding in the flat position, so you could 'bump-up' the parameters from the 'all-position' (aka 'colder') to the 'flat position' (aka 'hotter') parameters.  All-position 0.045 wire at 170 amps and 23 volts (remember, that is with CO2, so drop to ~22V using C25) at 260 ipm up to flat-position parameters at 260 amps at 27V (drop to ~26V using C25) and 500 ipm.So, I think you were running waaaay 'colder' than you thought or needed to.As DSW mentioned, you were probably also jumping the weave around to much and not letting the puddle fill-in properly (effective travel speed due to the weave 'jumps' was probably too large).  Thus undercut as well as possible inadequate tie-in (aka fusion aka penetration).Next, why such a large root gap?  That just means more weld to have to fill in the gap.  With some 0.045 wire you should have been able to get the gun tip and the wire down far enough to reach into the root area without having to have such a big gap.  Looking at the beam and guessing by the picture, you have about a 3/8" thick top flange with a 3/8" gap?  With a ~5/8" stick-out, you can pretty much get the wire tip down into the root with almost no root gap needed.Next, Hawaii is 'seismic-zone' territory for structural welding, right?  I don't see the 0.045 ExcelArc wire listed as D1.8 'rated' (just the 1/16" wire).http://www.hobartbrothers.com/upload..._71TypCert.pdfFrom the pictures you took, I can't see too well but it looks like the weld didn't penetrate too well into the backing bar.  Pic #2 and #3.Your cap weld looks relatively smooth and even though.    Just a little bit of a 'bobble' on the width.So, quick over-the-net-from-some-pictures-taken-too-far-away-to-see-the-weld-well diagnosis:- running too cold on the weld parameters;- running too slow on the WFS (spec sheet says 260 ipm at 23V or 500 ipm at 27V, using CO2)- jumping to far on the weave and not getting adequate penetration and fill-in;- excessive root gap causing more welding needed to fill in the huge root gap;Quick web search turns up another using commenting on using the ExcelArc 71 wire (in 0.045 with C25 as well) and being told and finding out that the shielding gas flow should be on the higher end to reduce/eliminate some porosity issues.http://www.hobartwelders.com/weldtal...h-Excel-Arc-71  The best laid schemes ... Gang oft agley ...
Reply:Hey there. I would like to suggest that you turn it up to at least 25.5 and go up from there. Adjust your wire accordingly. Watch how that wire trasnfers off the tip off that wire, it should lay itself right in there and the slag fall right off behind it. Also tighten up that weave to nil, just angle it back a bit off 90 and weave it enough to wash out the puddle. One observation I made from your pics is that your backing strip is awfully short. If you made it longer so you can start your welds well before the groove it will make things easier for you in the short and long run.Nothing Ever Got Done By Quitting, Never Give Up.
Reply:Originally Posted by MoonRiseHaven't used that wire myself, so just going to go by your listed info and the pictures and the spec sheet (right from the Hobart site)http://www.hobartbrothers.com/upload...xcel_Arc71.pdfThat wire is spec'd as using pure CO2 as well as C25 (multi spec E71T-1C and E71T-1M, as well as E71T-9C and E71T-9M), but note in the 'fine print' on the spec sheet that (as usual) the listed parameters were done using CO2 and if using C25 you have to drop the voltage ~1V.Next, you are welding in the flat position, so you could 'bump-up' the parameters from the 'all-position' (aka 'colder') to the 'flat position' (aka 'hotter') parameters.  All-position 0.045 wire at 170 amps and 23 volts (remember, that is with CO2, so drop to ~22V using C25) at 260 ipm up to flat-position parameters at 260 amps at 27V (drop to ~26V using C25) and 500 ipm.So, I think you were running waaaay 'colder' than you thought or needed to.As DSW mentioned, you were probably also jumping the weave around to much and not letting the puddle fill-in properly (effective travel speed due to the weave 'jumps' was probably too large).  Thus undercut as well as possible inadequate tie-in (aka fusion aka penetration).Next, why such a large root gap?  That just means more weld to have to fill in the gap.  With some 0.045 wire you should have been able to get the gun tip and the wire down far enough to reach into the root area without having to have such a big gap.  Looking at the beam and guessing by the picture, you have about a 3/8" thick top flange with a 3/8" gap?  With a ~5/8" stick-out, you can pretty much get the wire tip down into the root with almost no root gap needed.Next, Hawaii is 'seismic-zone' territory for structural welding, right?  I don't see the 0.045 ExcelArc wire listed as D1.8 'rated' (just the 1/16" wire).http://www.hobartbrothers.com/upload..._71TypCert.pdfFrom the pictures you took, I can't see too well but it looks like the weld didn't penetrate too well into the backing bar.  Pic #2 and #3.Your cap weld looks relatively smooth and even though.    Just a little bit of a 'bobble' on the width.So, quick over-the-net-from-some-pictures-taken-too-far-away-to-see-the-weld-well diagnosis:- running too cold on the weld parameters;- running too slow on the WFS (spec sheet says 260 ipm at 23V or 500 ipm at 27V, using CO2)- jumping to far on the weave and not getting adequate penetration and fill-in;- excessive root gap causing more welding needed to fill in the huge root gap;Quick web search turns up another using commenting on using the ExcelArc 71 wire (in 0.045 with C25 as well) and being told and finding out that the shielding gas flow should be on the higher end to reduce/eliminate some porosity issues.http://www.hobartwelders.com/weldtal...h-Excel-Arc-71
Reply:Originally Posted by CsparksFirst I'd like say thanks a lot for the great feedback and taking the time to get down to details.Your point about dropping 1 Volt for the mixed gas is appreciated.  I tried running hotter and faster with much improvement but still not quite up to the wire speed per the charts.  I did an overhead at 24.6 volts / 230 ipm which is slow but could not manage the increase speed & still keep the bead flat enough + the penetration seemed ok.  My puddle control is improving as I get used to this wire.   I am going to take your advise and that of DSW to try hotter and faster still in other positions.  Very observant of you to notice the point about seismic design.  Our county (Maui) in Hawaii does not actually require seismic design at this time and we were only given a basic spec. for 70,000 psi wire.  In the future they may require hurricane resistant design, but it is not on the books yet.  I was stuck with maxed out root gap (1/2" material with 3/8" root) due to a fit up problem but am trying to avoid that in the future and totally agree this is not desireable. Thanks for the comment about the gas.  I am pretty maxed out on my gas flow now and am also using a wind screen to keep the gas where it is supposed to be.  So far no porousity problems but any wind at all can cause significant problems without the screen.  This wire is very nice now that I am getting used to it but can't handle any major wind.  I had to go to a FCAW-G on a day where the wind was more than my screens could handle.
Reply:Whoops, thanks for the clarification.  I did actually mean the FCAW-S (self shielded) for E71T-11 wire to use on windy days.  Thanks
Reply:looks pretty good to me! could be better...but you might wanna tighten that weave up... the way you are doing it in the pictures looks like it's asking for some undercut!
Reply:i would cut that weave in half.Vantage 500's LN-25's, VI-400's, cobramatics, Miller migs, synch 350 LX, Powcon inverters, XMT's, 250 Ton Acurrpress 12' brake, 1/4" 10' Atlantic shear,Koikie plasma table W/ esab plasmas. marvel & hyd-mech saws, pirrana & metal muncher punches.
Reply:That's a very common wire in the shop for me.Usually running 27-28v, between 325-450 wire. If I'm doing the final pass on a horizontal weld, I'll crank up the wire a little bit and make sure I angle the gun upward to force the weld on the top edge (also making sure the work piece is as cool as possible before the final pass)If you're in the flat, definitely go warmer than you are! Don't be afraid to get up in the 26-27 range. It gets easier once you get past 27 or so. You have to move quicker yes, but your puddle will wet out much easier.I didn't see you say it... but are you pushing or pulling?I ALWAYS thought you had to pull with FCAW. But then I got to the shop I'm at now, and the foerman was like hahaha you silly new guy, who said you can't push FCAW?My school told me you can't actually...But anyway, he said you can push/pull and do whatever you want. They pass RT/UTs just fine pushing... I haven't failed one yet since I started pushing. I've only done about a dozen so far that I've pushed on, but no fails yet because of it.... Surprised, everything I knew about FCAW was flipped up side down when I came to this shop.
Reply:pushing doesn't give you the same penetration as pulling... i go straight into it... i dont push or pull... i carry the puddle. least amount of spatter
Reply:I have heard the pushing doesn't get good penetration statement for 20 years now and have always had better looking and less spatter with a little push. I run a 71t-1-hym wire all the time and try to run around 26 volts when welding flat. E71 wire doesn't like to be weaved back and forth when welding flat. Maybe a 1/4" back and forth at most and always forward. When welding vertical, weave to your hearts content, it will lay right in there nicely.CERTIFICATIONS:7018M- H.V.O10718M- H.V.O11018M- H.V.O9N10- H.V.O71T-1-HYM- H.O.V100S1 PULSE ARC 0,035- H.O.V100S1 PULSE ARC 0.045- H.O.VER70S-3 PULSE ARC 0.035 H.O.VER70S-3 PULSE ARC 0.045 H.O.VER5554- H.O.V
Reply:More power, less weave, burn it in there hot and deep.Disclaimer; "I am just an a$$hole welder, don't take it personally ."