I have had dual shield do that when using a spool that had been sitting around for a long time or when the piece got to hot, not from the machine settings but from welding too many passes without sufficient cooling time, which is pretty easy to do with dual shield.

Hello bbwinc, try doing a search of the forum, there have been lengthy conversations on other threads concerning the issue that you are asking about. To generalize however, one major factor has been moisture that has found it's way into the flux core of the wire. Flux-cored wires have 3 basic designs for their construction, they have a butt type seam, they have an over-lapped seam, or they have a bead-locked type seam. The bead-locked seam appears to provide the best resistence to moisture contamination and thus shows less issues such as the defect that you have referred to. So, in conclusion, be sure that you have fresh wire that hasn't been sitting around for countless time which would allow contamination. If it's used wire that has been taken off of a machine and stored somewhere be sure that it has been stored properly(properly stored would probably take some defining), likely it means in a sealed enclosure or container and better yet one that was heated to keep moisture from collecting. Finally do a bit of homework and try to determine if the wire was manufactured with the bead-lock type method as this might increase the time that the wire could be left out without picking up moisture. Just a bit of food for thought. Best regards, aevald

We experienced that when I found one of my welders running out of the procedure with his voltage and travel speed. He figured he could talk most of the day away and then play catch up by adding some voltage and travel along quite a bit faster.

What wire are you using ? When making a large pass in the flat or horiz fillet position an E70T-xx will be less likely to show this than E71T-xx . Because it is stopping at the surface it is due to the slag freezing before the gas gets out. Slag freezes faster on an E71T wire than it does on an E70T. Here are some ideas

1) If the pass is very thick it may take longer for the gas to escape. The slag freezes before the gas gets out. Try making a few smaller passes.

2) Rust or other contaminants may be generating gas. Make sure the joint is clean.

3) If you are using an all position wire in the flat position, try an E70. I have never seen the "worm tracks" on a vertical weld. I have seen it on flat and horizontal fillets.

4) Check the base material composition. Some elements may increase the possibility of porosity.

Have a nice day

Gerald
Iuka, Ms

i've found i get worm tracks sometimes when my stickout is too short. 

you know we had that problem  and we tried everything  even the old rolling the bottle    someone told me you can run pure co2  to get that out  but we didnt have a bottle of co2  so we kept messing with it  and i found that having proper stick out and travel speed was a major contributer  i found that 3/4 stick out at least   made a worlds of diffrence

Just my 2 cents
Try 1/8 to 1/4" of tip recess into the cup, it increases resistance provided the same stickout is used, it preheats the wire. If you've been running it flush  you'll need to bump your volts up 1-2. If its old auction wire toss it and get new stock!
good luck
Whiteyford

Here is something from Lincoln regarding the condition you speak of. I found it today looking up information on Self Shielded FCAW.13. http://www.lincolnelectric.com/knowledge/articles/content/20faq.asp#13

Gerald
www.weldingdata.com