7018 on DCEN?
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Thread: 7018 on DCEN?

  1. #1
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    7018 on DCEN?

    I've always read and also been told to run 7018's on DCEP. My welding instructor at school tells us to run it on DCEN. I think they run a lot better on DCEP. Why is this? Thanks!
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  2. #2
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    Re: 7018 on DCEN?

    You need to ask your instructor his reason.

    Some people run them negative on first pass open root pipe. Then switch back.

    DCEP is the preferred polarity for general welding.
    Dave J.

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  3. #3
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    Re: 7018 on DCEN?

    So far we're just padding beads on plate. I'll see what he says.
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  4. #4
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    Re: 7018 on DCEN?

    For open root pipe with 7018, I run it on DCEN. For the hot pass and fill I run DCEP.
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  5. #5
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    Re: 7018 on DCEN?

    I have ran 1000's of them,,, never ran one on N. That looks really good on pipe. I wish I had the dilligence to keep up and practice a little but it just doesn't interest me enough.

  6. #6
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    Re: 7018 on DCEN?

    you need to find a new 'instructor'.

  7. #7
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    Re: 7018 on DCEN?

    You can always reference what Lincoln Electric recommends in their SMAW welding guide. No mention of DCEN.

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    Re: 7018 on DCEN?

    Running low-hydrogen rods on DCEN for open root is quite normal here in Europe. DCEN on SMAW puts less heat in the base metal so it's easier to control the keyhole and not blow through. 7018 is a difficult rod to run on DCEN for open root, 7016 on DCEN makes it a lot easier because the puddle is less fluid (a bit more fast freeze).
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  9. #9
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    Re: 7018 on DCEN?

    Quote Originally Posted by Oscar View Post
    You can always reference what Lincoln Electric recommends in their SMAW welding guide. No mention of DCEN.

    (click the pic)
    Lincoln in the Netherlands have a lot of different low-hydrogen rods and a lot can be run on DCEN as well as AC.

    Low-hydrogen electrodes start at page 90

    https://www.lincolnelectric.com/asse...alogue-eng.pdf
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  10. #10
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    Re: 7018 on DCEN?

    Quote Originally Posted by E T View Post
    Lincoln in the Netherlands have a lot of different low-hydrogen rods and a lot can be run on DCEN as well as AC.

    Low-hydrogen electrodes start at page 90

    https://www.lincolnelectric.com/asse...alogue-eng.pdf
    Good to know for the European welders, not sure if that necessarily applies to the inquiry of the OP, which is what I was more or less aiming for.
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    Re: 7018 on DCEN?

    Quote Originally Posted by E T View Post
    Running low-hydrogen rods on DCEN for open root is quite normal here in Europe. DCEN on SMAW puts less heat in the base metal so it's easier to control the keyhole and not blow through. 7018 is a difficult rod to run on DCEN for open root, 7016 on DCEN makes it a lot easier because the puddle is less fluid (a bit more fast freeze).
    i've seen a usa video on using 7018 running EN and its poor. i suspect its a lot to do with the actual electrode. in Europe where running 7018 in EN is common are, i suspect they are using electrodes that are made for that.
    they also have 6013 made specially for pipe welding.
    compared to USA where 7018 is probably not made for EN because they use 6010 or 7016 for open root.

  12. #12
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    Re: 7018 on DCEN?

    Quote Originally Posted by E T View Post
    Lincoln in the Netherlands have a lot of different low-hydrogen rods and a lot can be run on DCEN as well as AC.

    Low-hydrogen electrodes start at page 90

    https://www.lincolnelectric.com/asse...alogue-eng.pdf
    That link said, " whenever possible use dcep ". It doesn't say never use dcen. Also, it said on ac, increase amps, so, dcen works but less penetration. I think that's why they say stick welding is better for penetration when compared to tig welding.

  13. #13
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    Re: 7018 on DCEN?

    Quote Originally Posted by Keith Merrell View Post
    I've always read and also been told to run 7018's on DCEP. My welding instructor at school tells us to run it on DCEN. I think they run a lot better on DCEP. Why is this? Thanks!
    DCEP or reverse polarity has more penetration because of electron flow. Electrons get ripped out of the work and flow to rod instead of the other way. Your instructor maybe teaching something and testing how well you follow instructions. Maybe?

  14. #14
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    Re: 7018 on DCEN?

    Here are some welds using DCSP (direct current standard polarity ) which is DCEN.
    I chose the wrong setting while making practice welds. That is why you should do practice welds.
    It welded nice and easy and the welds look pretty good even with the wrong setting. I will redo with DCEP.
    Settings
    Linde 305
    Initial pass: 6010 1/8” rod 90 amps
    2 caps : 7018 1/8” ~ 120 amps.
    Both on DCEN


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  15. #15
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    Re: 7018 on DCEN?

    Quote Originally Posted by Keith Merrell View Post
    I've always read and also been told to run 7018's on DCEP. My welding instructor at school tells us to run it on DCEN. I think they run a lot better on DCEP. Why is this? Thanks!
    As far as I know, below is still the current welding theory.
    It explains why DCEP penetrates deeper than electrode negative. Which is the reason to use one or the other.

    An excerpt from Modern Welding:

    "...there is a jet action and/or expansion of gases in the arc at the electrode tip. This expansion causes the molten metal to be propelled with great speed across the arc. The molten metal impacts the base metal with greater force. This heavy impact on the base metal helps to produce deep, penetrating welds."
    ~Modern Welding 1997 Althouse, Turnquist, Bowditch, and Bowditch.


    Note: tig is the opposite...DCEN for penetration.
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  16. #16
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    Re: 7018 on DCEN?

    Quote Originally Posted by jeffrey.penfield View Post
    Here are some welds using DCSP (direct current standard polarity ) which is DCEN.
    DCSP: direct current straight polarity, DCEN
    DCRP: direct current reverse polarity, DCEP
    Dave J.

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  17. #17
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    Re: 7018 on DCEN?

    Quote Originally Posted by MinnesotaDave View Post
    DCSP: direct current straight polarity, DCEN
    DCRP: direct current reverse polarity, DCEP
    When someone asks ,”What is the orientation of your polarity?”, do you say straight or standard?


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  18. #18
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    Re: 7018 on DCEN?

    How do my welds look?


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  19. #19
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    Re: 7018 on DCEN?

    Quote Originally Posted by jeffrey.penfield View Post
    How do my welds look?


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    I can't see any pictures in your post.
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  20. #20
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    Re: 7018 on DCEN?

    Quote Originally Posted by E T View Post
    I can't see any pictures in your post.
    Here you go:



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  21. #21
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    Re: 7018 on DCEN?




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  22. #22
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    Re: 7018 on DCEN?

    jeffrey.penfield, excellent job on the pictures! Good lighting, and in-focus! Welds look like mine, average for a hobbyist. I think I see a little bit of porosity or might be slag bits, but pretty sure it's a few pores here and there. Your cut-out cross-section shows good wetting of the toes/edges, but with out doing an etch, you won't know how well it penetrated into the root. If you have a roloc 2" pad on a small 90° grinder, you can polish it out, warm up the piece, and dab Naval Jelly on the cut and it will reveal the weld nugget separate from the base metal.
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  23. #23
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    Re: 7018 on DCEN?

    I'm with Oscar. Welds look ok penetration wise. Your travelspeed looks a bit inconsistent and a bit to fast at times.
    The porosity is start porosity which happens with 7018 with cold starts. When you strike an arc with 7018 you have to long arc a bit right after and double back to just before where you struck the arc. Then move on with normal arc length and weld over the start.
    The slight longarcing heats up the base metal and the rod a bit because the welding voltage rises. When you then weld over the start the rod is up to temp and you burn out that porosity.
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  24. #24
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    Re: 7018 on DCEN?

    Quote Originally Posted by jeffrey.penfield View Post
    When someone asks ,”What is the orientation of your polarity?”, do you say straight or standard?


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    DCSP: direct current straight polarity, DCEN
    DCRP: direct current reverse polarity, DCEP
    Dave J.

    Beware of false knowledge; it is more dangerous than ignorance. ~George Bernard Shaw~

    Airco 300 - Syncro 350
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  25. #25
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    Re: 7018 on DCEN?

    Quote Originally Posted by Oscar View Post
    jeffrey.penfield, excellent job on the pictures! Good lighting, and in-focus! Welds look like mine, average for a hobbyist. I think I see a little bit of porosity or might be slag bits, but pretty sure it's a few pores here and there. Your cut-out cross-section shows good wetting of the toes/edges, but with out doing an etch, you won't know how well it penetrated into the root. If you have a roloc 2" pad on a small 90° grinder, you can polish it out, warm up the piece, and dab Naval Jelly on the cut and it will reveal the weld nugget separate from the base metal.
    I was studying the topic of polishing and etching my weld. I have the pads and naval jelly. I will use a butane torch for the heat source. How hot should it get? Do I preheat, then apply naval jelly, apply and then heat or apply, clean and then heat?


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