Feedback Request on Welding Technique and Settings

[Csparks]

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

[exwldr]

weld's look nice. are nice & clean ,no undercut, no visible porosity. good job! i would have used 3-4 passes for the cap instead of making the beads so wide though...

[jpence38]

It looks to me that all of your trouble is due to the "weaving" you are using trying to cover as much area as possible during your fill passes.
Any particular reason you did not use a 1/16 wire for this. Then there would be no need for weaving, just run straight fill passes eliminating the undercut and wagon tracks.
Also, the settings for your wire in the flat are recommended to be around 27 volts, 500 ipm wire speed, 260 amps and 3/4" stick-out.

http://www.hobartbrothers.com/uploads/pdf/datasheets/Excel_Arc71.pdf

[Csparks]

Thanks for the feedback

It looks to me that all of your trouble is due to the "weaving" you are using trying to cover as much area as possible during your fill passes.
Any particular reason you did not use a 1/16 wire for this. Then there would be no need for weaving, just run straight fill passes eliminating the undercut and wagon tracks.
Also, the settings for your wire in the flat are recommended to be around 27 volts, 500 ipm wire speed, 260 amps and 3/4" stick-out.
http://www.hobartbrothers.com/upload...xcel_Arc71.pdf

You raise some good questions. I was using the .045" wire since I need to weld some thinner material in the same job and did not want to have to keep changing the wire, but am re-thinking this based on your comment (but will need to watch my duty cycle closer with the larger wire since I am running my XMT350 on single phase power input for this job). I think you are right too that I should have run this a lot hotter in the flat position which in itself would have created a larger bead with less need for weaving. Thanks for the link and the thoughtful comments. I am going to take another look at my wire and settings for this job.

[tattyrat]

why the big gap and shallow prep angle

from experience i would run with the 045 wire at this thickness but decrease gap to 3mm and steepen prep to 37 run stringers rather than weave

[Daniel]

I would reduce the gap like tattyrat said and i would do a 90 degrees on the one side and 37 bevel on the other side, less fill that way.
And extend your run in and out, I see on your pictures that you're not really using them. It is a good idea to use them .

[turbo38t]

Crank the heat......I'd consider co2 for this too.....

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

[Csparks]

Grateful for the Feedback

Thanks to exwlder for the encouraging comments. Much appreciated.
jpence38, your comments and link were very helpful
Good points Tattyrat on narrowing the gap but sticking with the .045"
Daniel's point about going to a single bevel groove weld which is also prequalifed sounds a lot smarter and agree running into the bevels better is an important improvement I will work on. Thanks all for taking the time to help me get the best results. I live and work on a small island in Hawaii and this kind of specific feedback is hard to come by. Aloha

[jpence38]

Just goes to show ya, "There is more than one way to skin a cat".

PITA Disclaimer: There were no animals hurt during the production of this post.

[Csparks]

Just goes to show ya, "There is more than one way to skin a cat".

PITA Disclaimer: There were no animals hurt during the production of this post.

So true. Thanks for the good humor with the disclaimer for the PITA folks. I guess you can't be too careful in what you say these days, but I am sure we are all gentle spirited welders here. Though men of steel, we'd never harm such an innocent creature!

[beamwalker]

personally i wouldnt weave so wide...the weld could possibly crystalize. id run stringers with 232 wire or use 7018. just me tho and what i was taught

[Csparks]

personally i wouldnt weave so wide...the weld could possibly crystalize. id run stringers with 232 wire or use 7018. just me tho and what i was taught

Thanks for the tip. I tried narrowing my weave and it is working better.

[kevin]

beam walker nailed it, stringers is the way to go, leaving all of those crows feet on the edges is asking for trouble unless you grind them out, so run stringers and crank up the machine and keep the gun straight up on flats and angled on bevels, just pushing slightly to keep spatta to a minumum and penatration to its fullest, and travel right along, dont let the weld build up and spill over into lack of fusion areas, orgrab a handfull of 7018, looks good what you have all ready done, have fun

[JTMcC]

In my opinion you need considerably more heat, specially if you're going to put in such wide fillers. Every one of those big distinct ripples on the edges are just a big bad UT trap. You might make it a few times but sooner or later a sharp UT tech is going to call a spot for lack of sidewall fusion.
If you split the fillers, you'll lose the traps, ensure better sidewall fusion, and have less tendancy to distort the beam.
Any gap (and those are pretty big) at the ripple edge is a trap, and will bite you eventually. More so if you aren't running smoking heat.
A harsh UT tech will call every blip, and the methods you're using are just going to mak it harder on yourself.
Looking at the web splice plate I'm guessing these are lightly loaded beams, but there's no sense making it harder than it should be.

J

[JTMcC]

personally i wouldnt weave so wide...the weld could possibly crystalize.

Well let's hope it does, otherwise it won't be steel.

Steel exists in a crystaline lattice structure. There are probably some good free books in your local library that will help you out here.
And there is (harder to find but on the web) info available on the good and bad points of wide weaves.

When someone talks about a weld crystallizing, it's time to walk away.

J