Avoiding arc start porosity on 7018?

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I never leave the nest so everything is always MIG and sometimes TIG.For the sake of having the ability I'm practicing on scrap here and there. This is 1/8" 7018 on 100 amps from a powermig 210.I think my beads are "decent" but the arc start is always ruined with porosity. I have tried starting 1/2" or so inward, and quickly whipping back once its lit as well as slowly bringing it back. Nothing I try seems to improve it.www.FirehouseFabricators.comZachLincoln 210mpLincoln SW200Hypertherm Powermax 45xp2x4 CNC Plasma Table.
Reply:Try 1" and slowly move it back.  Make sure you get the right arc length when you get to the apart of where the bead is going to go. 1st on WeldingWeb to have a scrolling sig! HTP Invertig 400HTP Invertig 221HTP ProPulse 300HTP ProPulse 200 x2HTP ProPulse 220MTSHTP Inverarc 200TLP HTP Microcut 875SC
Reply:Just curious what brand of rod that is. And, a lot of times the need for clean material gets (over) stressed in my opinion, but this time it did get my attention. It looks like there is a fair amount of rust in the area where you have the porosity. Could just be how the photo looks. About the only suggestions I have come in the form of questions. Is the porosity coming from an unused electrode? Or from re-strikes. If it is coming from an unused electrode, the first time you use it, then it "could" be when you strike it to begin welding, your fear of sticking it to your plate is causing you to lift the electrode too high, initially giving you too much arc length.If porosity is coming from when you re-strike, then I would suggest grinding, filing, sanding, or whittling the end off the electrode before re-striking. Some 7018 rods seem more prone to get a mixture of molten slag and weld material glued to the end of the rod at the end of a weld, causing porosity when beginning the next pass But yes, the rest of your beads look fine. Don't forget that 7018 works best without any of the whipping, or forward and back motion, that is often employed with the 6010/11 electrodes.Good luck! Sent from my E6810 using http://tiny.cc/Forums_reader
Reply:My sweet spot for 1/8 7018 is 115 to 125A. Maybe a little cold @ 100A. I strike ahead of my start, long arc a little to heat the rod & stabilize the arc (engine drive), then move back to start & stuff it in to make sure I have a short arc then pause for just a micro second to let a clean puddle form. I find that a cold rod nearly always leaves a little porosity.
Reply:Turn your amps up. On that practice piece after a bead or 3 you would be running too hot tho. On 1/8" 7018 I would be in the 115-130 amp range depending on thickness, joint configuration and position. The 2 main causes for porosity ( excluding rust, paint or oil) are too low of amps or starting with too long of an arc.
Reply:Originally Posted by BrooklynBravestI never leave the nest so everything is always MIG and sometimes TIG.For the sake of having the ability I'm practicing on scrap here and there. This is 1/8" 7018 on 100 amps from a powermig 210.I think my beads are "decent" but the arc start is always ruined with porosity. I have tried starting 1/2" or so inward, and quickly whipping back once its lit as well as slowly bringing it back. Nothing I try seems to improve it.
Reply:Thats a piece of HRPO 3/16" plate scrap from my plasma table.Its definitely not rusty or oily but I didnt take any time to prep the surface either. I'd prefer to learn 7018 because its such a commonly used rod.  I'm literally just burning a couple rods every time I go out for practice.www.FirehouseFabricators.comZachLincoln 210mpLincoln SW200Hypertherm Powermax 45xp2x4 CNC Plasma Table.
Reply:What are your Arc force, and Hot start settings ? Is your polarity  correct (sometimes I have things switched around because its multi purpose, it happens occasionally), sometimes going to "Home" and going through the settings helps me remember.Seems a little cold amperage wise for most  1/8" 7018 work, but if you need to run that amperage( welding thinner metal and or vertical ) , increase your hot start. 3/32" 7018 runs good 85-100 amps.Good luckLast edited by albrightree; 2 Days Ago at 10:29 AM.Airco 250 ac/dc Heliwelder Square waveMiller Synchrowave 180 sdMiller Econo Twin HFLincoln 210 MPDayton 225 ac/dcVictor torchesSnap-On YA-212Lotos Cut60D
Reply:Originally Posted by albrightreeWhat are your Arc force, and Hot start settings ? Is your polarity  correct (sometimes I have things switched around because its multi purpose, it happens occasionally), sometimes going to "Home" and going through the settings helps me remember.Seems a little cold amperage wise for most  1/8" 7018 work, but if you need to run that amperage( welding thinner metal and or vertical ) , increase your hot start. 3/32" 7018 runs good 85-100 amps.
Reply:This is a common problem, common enough that Lincoln publishes guidance on how to avoid ithttps://www.lincolnelectric.com/en-g...ty-detail.aspxMiller Multimatic 255
Reply:Credit to Louis 1961 from 2015http://forum.weldingtipsandtricks.co...pic.php?t=7029https://www.lincolnelectric.com/en-u...ty-detail.aspx---Meltedmetal
Reply:Here in Japan, we call this kind of porosity from LH rods "blow holes," and it mostly caused by what we call "start blow." Not to be confused with arc blow due to magnetic forces, but the same effect with the arc wandering around. To mitigate the effect, try starting the rod quite a bit farther forward, like maybe a full inch. After the back step, hold the rod there for a second to let the puddle build, and arc firmly establish, and keep the rod angled back. Here's a video on a A-2F qualification with LB-47 (E7016) showing the back step and rod angle. English subs, but not all clear translations...
Reply:Originally Posted by JDM WelderHere in Japan, we call this kind of porosity from LH rods "blow holes," and it mostly caused by what we call "start blow." Not to be confused with arc blow due to magnetic forces, but the same effect with the arc wandering around. To mitigate the effect, try starting the rod quite a bit farther forward, like maybe a full inch. After the back step, hold the rod there for a second to let the puddle build, and arc firmly establish, and keep the rod angled back. Here's a video on a A-2F qualification with LB-47 (E7016) showing the back step and rod angle. English subs, but not all clear translations...
Reply:Originally Posted by farmersammmThat really looks nice(actually BEAUTIFUL) until the last pass.  It's a bit too proud of the plate.  Too much metal piled up.It's a booger to judge bead height in these kind of welds, been there, done that  I find that viewing the puddle from the side works best, if you can get in a position to look from this angle.  Flat welds can sorta suck in a way.  See how the weld is not extremely convex, but relatively flat, but still blending nicely with the edge of the joint.  A side view gives you a very good approximation of bead height.  All welds not more than maybe 1/16 over the top of the plate.This is a funny!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!    I was just starting to lose my eyesight when I made these welds.  I took this pic in the mirror I think, right at the time this project was in process.  I'm probably at my peak here, and that's about as good as I'll ever weld again for the remainder of my days.  The welds made since, haven't been up to snuff.  I'm getting closer to committing to cataract surgery I guess  And I'm not keen on doing welding critique these days, because I'm not doing much better since the eyes started going.Anyways.............you got some good stuff there, just try to flatten out that final pass
Reply:Originally Posted by BrooklynBravestI never leave the nest so everything is always MIG and sometimes TIG.For the sake of having the ability I'm practicing on scrap here and there. This is 1/8" 7018 on 100 amps from a powermig 210.I think my beads are "decent" but the arc start is always ruined with porosity. I have tried starting 1/2" or so inward, and quickly whipping back once its lit as well as slowly bringing it back. Nothing I try seems to improve it.