NR211 MP porosity

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I have a small mobile welding business. I do mostly small stuff in the residential market.I like it, and it keeps me busy. I have a shop as well, but prefer the mobile work.I recently started using Lincoln NR211MP instead of stick for my repairs that cannot be done with GMAW or GTAW.I like this wire, it is very versatile, but every once in a while, I get what looks like to be porosity in my welds. It usually happens at the most inopportune time as well.I cannot really tell what is going on differently when this happens. It certainly is not wind blowing away any shielding that is causing it.I have a Miller TB302 and run this wire using a Miller 12RC feeder. I currently have 035 wire in there and have been experiencing this porosity quite a bit lately.Is there something specific that causes this defect when running this wire? What more info can I provide to try and get some good advice on this?Thanks for the help,RussMiller 302GMIller 12RC SuitecaseMIller 30A spoolgunHF-251D-1WP17 Tig torchSmith HD torchHypertherm 45Jet drill pressHF 7X12 wet cut horizontal band sawPlasmacam CNC table
Reply:I also have this problem with gasless wire and am keen to hear the replies.I have found that mill scale and rust causes this but even with this removed I still sometimes get porosity.Possibly moisture in the flux?
Reply:did you reverse your polarity?  you have to switch the power leads on your welder or wire feed to do this.  it will weld superb then.  Basically 6011 in wire formwww.burdettenetworks.com
Reply:kburd is right, most self-shielded flux core runs DCEN.
Reply:Too much voltage.A good way to tell, is make sure the entire weld is covered with slag when you're done welding. No open spots. First chance you get I'd switch to NR-212. Attached ImagesDon’t pay any attention to meI’m just a hobbyist!CarlDynasty 300V350-Pro w/pulseSG Spool gun1937 IdealArc-300PowerArc 200ST3 SA-200sVantage 400
Reply:Moisture. Keep gun angle steep.Lincoln NR211MP is a structurally rated wire, and is multiple pass(MP) AWS E71T-11Last edited by Donald Branscom; 05-19-2011 at 06:05 PM.AWS certified welding inspectorAWS certified welder
Reply:Echo what CEP says. With 211 watch that the slag isn't on the blackish side and/or with open areas with little to no slag. If so the votage to wirespeed (amps) relationship is off. Watch the slag puddle and make sure it's coming along behind you. It'll almost look like a clear drop of water on top of the bead. If you happen to slow down and the puddle catches up you have to move on, it doesn't like firing (arcing into that deep puddle for some reason. I like a pretty slight angle, close to verticle and a short stickout. Check the preheat section once in a while. I like about 1/8th to 3/16ths myself."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:cool guys, thanks a lot for the info. it was too much voltage that was causing me trouble.I have a tendancy to run stuff too hot.I was not getting that complete slag coverage and there were plenty of blackish areas.I also bought a 10lb spool of the NR212 to give that a try.Thanks again for the info.....very appreciated.RussMiller 302GMIller 12RC SuitecaseMIller 30A spoolgunHF-251D-1WP17 Tig torchSmith HD torchHypertherm 45Jet drill pressHF 7X12 wet cut horizontal band sawPlasmacam CNC table