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Thread: Laying 7018 on 6010, freeze lines, dealing with slag

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    Laying 7018 on 6010, freeze lines, dealing with slag

    For times when the cleaning ability and/or penetration of 6010 are good attributes it would make sense to use it. However, I am finding the pool freeze lines tend to hang on to slag like theres no tomorrow. Specifically with whip-and-pause - the next pool is pushed back on top of the previous which leaves a rather coarse "stack of coins" profile. Those ridges between the "coins" are what I am mostly referring to.

    When coming back over the initial bead with 7018 to build up a fillet weld, for example, the slag has to be gone and just base + bead metal.

    How do you go about getting the slag out from the ridges between the coins on the 6010 pass?

    I am just goofing around on some metal I can mess around with right now, but I have a project coming where this method might be used. If it ends up too difficult/time consuming I'll re-think the plan. What I don't want to do is lay the initial bead then have to grind the ridges down smooth, removing the slag in the process of smoothing out the profile. A wire wheel is one thing - but it skips right past the valleys where the slag is at the moment.

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    Re: Laying 7018 on 6010, freeze lines, dealing with slag

    Quote Originally Posted by FlyFishn View Post
    What I don't want to do is lay the initial bead then have to grind the ridges down smooth, removing the slag in the process of smoothing out the profile.
    Hmmmmmm,, in my training,, if you do not want to take out the ridges,,
    you may want to consider a new hobby like tennis??

    Really, the answer is not wanting to take out the ridges,, it is having a big enough grinder,,
    When I trained, we had a pneumatic grinder that was so powerful, it could take out the ridges as easily as the wire brushing you are discussing.

    7018 is an unforgiving welding rod,, get the base matal, and previous welds clean,, or fail.

    If 7018 could be welded with ridges remaining,, someone would have figured it out a half century ago,,

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    Re: Laying 7018 on 6010, freeze lines, dealing with slag

    I have run a root pass of 6010, scratched the slag off with the end of a rod, then laid a hot pass of 7018 right on top of it. No brush, no grind at all.

    The 6010 slag will wash right off & mix with the 7018 flux if it is done right.

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    Re: Laying 7018 on 6010, freeze lines, dealing with slag

    Just ise a wire wheel. Certainly do a good job, but don’t overly worry about it. The 7018 arc remelts the ridges and any remaining slag and it floats to the top in the new pool of slag. If you think this is a problem, just make a 6010/7018 coupon, slice it up, bend it, etc, and look for slag deposits.

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    Re: Laying 7018 on 6010, freeze lines, dealing with slag

    In my experience, if the bead of 6010 is put in properly, the slag is so thin that you hardly need to remove it before welding on top of it. If subsequent beads are hot enough, they just melt the slag left by the 6010 and float it to the top. (7018 is another story. So are "wagon tracks" at the toes...)

    Didn't somebody just recently post up about how they welded pipe with nothing but 6010 and never touched the slag between layers, and it x-rayed fine?

    If you're getting a lot of slag inclusions with your 6010, try going hotter/slower to let any undercut fill in more at the toes. If this causes you to blow through, you can pause momentarily to let the heat wick away, then resume...
    Last edited by Kelvin; 04-24-2021 at 09:44 AM.

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    Re: Laying 7018 on 6010, freeze lines, dealing with slag

    Quote Originally Posted by Kelvin View Post
    If you're getting a lot of slag inclusions with your 6010, try going hotter/slower to let any undercut fill in more at the toes. If this causes you to blow through, you can pause momentarily to let the heat wick away, then resume...
    What I am playing with right now is blowing out some earlier poorly done welds that are not uniform with slag. I'm using the 6010 to flush it out. This is far from a normal process, I'm just screwing around with it as an exercise. What you say about blowing through is a good thought. I'm getting all the way through, but have to be careful not to get too far. Original beads were 6011. Once I get the bead built up, crap flushed up, etc I'm left with the ridges. So the slag at the top is partly a good thing - thats where it should all be - with the trapped crap. I suppose if I can brush what is left from the 6010 and burn the 7018 hot enough over it like you guys say then that will work fine.

    As to a destructive test - on the parts I'm messing around with I don't want to do that this round, but that is certainly in order for the next project. I plan on getting more metal than I need just for that reason - maybe some etching if not just bend testing. Which reminds me - I need to build a jig for the hydraulic press for bend tests.

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    Re: Laying 7018 on 6010, freeze lines, dealing with slag

    Angle Grinder + wire wheel. Can't see needing anything more. Oscillate the wire wheel side-to-side quickly as you're moving it up-and-down the length of the joint and it works pretty well for me.
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    Re: Laying 7018 on 6010, freeze lines, dealing with slag

    Quote Originally Posted by Oscar View Post
    Angle Grinder + wire wheel. Can't see needing anything more. Oscillate the wire wheel side-to-side quickly as you're moving it up-and-down the length of the joint and it works pretty well for me.
    Something I do on pipe work is push the wire wheel on the first pass and then flip and pull it (reversing the rotation) on the next. Brushing both directions gets most all the slag off.

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    Re: Laying 7018 on 6010, freeze lines, dealing with slag

    Pipe welders weld over top 6010 with 7018 all the time, I never seen em go crazy with a grinder, there is times workin on these buckets and such I gotta do the same thing. Those little ridges or bumps dont mean nothin if you are any good the 7018 will smooth it out.

    Just get rid of the slag with a chippin hammer and wire brush it, if you wanna use a wire wheel go ahead, it wont hurt nothin but grinding it smooth aint needed at all

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    Re: Laying 7018 on 6010, freeze lines, dealing with slag

    Power hacksaw blade 4" of teeth ground off for a handle, rake it down the bead.

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    Re: Laying 7018 on 6010, freeze lines, dealing with slag

    Quote Originally Posted by FlyFishn View Post
    What I am playing with right now is blowing out some earlier poorly done welds that are not uniform with slag. I'm using the 6010 to flush it out. This is far from a normal process, I'm just screwing around with it as an exercise. What you say about blowing through is a good thought. I'm getting all the way through, but have to be careful not to get too far. Original beads were 6011. Once I get the bead built up, crap flushed up, etc I'm left with the ridges. So the slag at the top is partly a good thing - thats where it should all be - with the trapped crap. I suppose if I can brush what is left from the 6010 and burn the 7018 hot enough over it like you guys say then that will work fine.
    .
    Cleaning up old trashy welds can be done with 6010. Just grind what you can to prep the joint config, & then weld over with 6010, slow down enough to get good penetration, but use care not to blow through. Lay in a good flat bead of 10, then scratch, brush or grind. Once you get a good clean layer of 10, you can lay a good hot pass on top of it. Extent of the prep depends on the strength requirement of the joint - if it it low strength, minimal prep, small groove, use 6010 to "wash" the crap to the surface, brush then fill with 7018. If the joint is a high strength joint, then groove almost all the way through, lay in a "wash pass" of 6010, then hot pass 7018 & then fill.

    I use this process a lot since I buy & repair a lot of used farm equipment. You wouldn't believe some of the welding you will see on old farm equipment! There is a reason why they call it farm code welding.
    Last edited by cwby; 04-29-2021 at 10:57 AM.

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    Re: Laying 7018 on 6010, freeze lines, dealing with slag

    I worked on some of the welds today. I left the 6010 the way I had it before and didn't worry about the grooves too much. First pass with 7018 was at about 120a. I tested the current on another piece to dial it in first. When I went to the work that first pass was a bit too cool so I bumped up to 125a. That seemed to be the sweet spot - I liked the penetration and with the weld metal under it already I had plenty of meat to penetrate in to = no risk of burning through. However, when I got to the edges (3/8" and 1/2" plates welded to 1/4" tubing) against the 1/4" I turned the amperage down to about 107-110 as I was getting too much under cut at 125a.

    In any event, the process seemed to work. My goal was to build up a weld fillet and get some rod burning practice in. It all worked well. Although, I am getting some porosity at times in the rods - 7018-H8 from Lincoln (they are an AC version, but I ran DCEP). I will see if I can get some other ones from the LWS and see how they run. The box I was using is from Home Depot.

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    Re: Laying 7018 on 6010, freeze lines, dealing with slag

    Quote Originally Posted by FlyFishn View Post
    I worked on some of the welds today. I left the 6010 the way I had it before and didn't worry about the grooves too much. First pass with 7018 was at about 120a. I tested the current on another piece to dial it in first. When I went to the work that first pass was a bit too cool so I bumped up to 125a. That seemed to be the sweet spot - I liked the penetration and with the weld metal under it already I had plenty of meat to penetrate in to = no risk of burning through. However, when I got to the edges (3/8" and 1/2" plates welded to 1/4" tubing) against the 1/4" I turned the amperage down to about 107-110 as I was getting too much under cut at 125a.

    In any event, the process seemed to work. My goal was to build up a weld fillet and get some rod burning practice in. It all worked well. Although, I am getting some porosity at times in the rods - 7018-H8 from Lincoln (they are an AC version, but I ran DCEP). I will see if I can get some other ones from the LWS and see how they run. The box I was using is from Home Depot.
    Sometimes, if you're concerned with undercut at the end of a weld that terminates on the end of the plate.........you can weld in from that edge instead of welding to it.

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