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Thread: TIG welding high carbon steel question

  1. #1
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    TIG welding high carbon steel question


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    When tig welding high carbon steel I sometimes get vast quantities of porosity. I was wondering if anyone out there know how to avoid this. I can solve the problem by useing a nickle stick welding rod as my filler, but I would like to have a solid steel joint. I am hopeing the easiest solution isn't building a forge and forge welding. Thanks.

    WS

  2. #2
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    Tenino, WA US
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    TIG

    First question that comes to mind is what are you using for filler metal? Oxy/acet rod will fill up w/ porosity if you try to use it for TIG. Next thought - gas coverage: pure argon right? 15 -22 CFM.

  3. #3
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    I talked to my tech herre at work and she said there are tons of reasons why you could get porosity. She mentioned the same stuff and Bill did, and she said the biggest thing is to make sure your material are clean.

    Supposedly impurities come out of the metals when you weld them, and oil can "soak into" the "pores" of the steel and cause porosity. That is what she told me and she has been welding for 18+ years.

    Hope this helped.

    I wouls say, build a forge, and forge weld. It is more fun that way.

  4. #4
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    Thanks for the replies. I have run into the problem with oil before. I'll make some filler rod out of good material and see if that helps.

    WS

  5. #5
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    Anytime we had to weld carbon steel in the shop.
    we preheated it frist

  6. #6
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    Jan 2000
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    Alberta, Canada
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    Insanity.

    I work for a large pipeline company and have access to all sorts of welding specialists. I bounced your question off one of my welding foremen and he gave me the following info for you to consider:

    quote:
    - the weld area must be clean - i.e. no contamination at all
    - if you get porosity at all when you start welding, you must grind out all of it or it will come back over and over again
    (this is likely where they're having the most problems) and this gets pretty frustrating
    - thinner material is prone to porosity
    - depending on the type of high carbon steel, either lots of preheat or none at all might be part of the problem
    - proper gas flow/coverage is a must i.e. too much or too little and you will never get rid of the porosity and it's a very fine line. Usually takes some experimentation to get this right.
    - if you can better identify the type/grade/thickness of the steel, we can give you somewhat 'exact' welding instructions
    - when in doubt use a type of electrode called 'Inkonel' (either TIG or stick electrode). It works best for the high carbon stuff and my best TIG guys swears by it.
    Are they having cracking problems too?
    Tell them even the best 'professional' TIG welders have trouble with high carbon steel.
    :unquote

    What kind of carbon steel were you working with?

    Good luck!
    Diligence

  7. #7
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    Tuscaloosa, AL
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    The pieces that were giving me the trouble were rebar, so I don't know anything about it. This piece was a test piece since I'm learning how to forge. It won't see actual use or I wouldn't have used an unknown steel. I managed to get some decent results by grinding out over halfway on one side, rewelding (2% thoriated tungsten) with gas set at 20 psi (machine doesn't have a flow meter ) pure argon, useing filler rod I sheared of a piece of 15n20 sheet I bought in a fit of overconfidance to use in a damascus bilet, then ground the other side out past halfway and rewelded. There is no visible cracks or porosity now and after ht it survived being thrown into a concrete floor. It's a sai by the way. Does the inkonel work better than monel?

    WS

  8. #8
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    Manchester, PA, USA
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    Inconel® is a family of special stainless steels with relatively high nickel content that is commonly used in high heat applications.

    Make sure you also use a gas lens (diffuser) when TIG welding carbon steels.
    Last edited by Tom Anderson; 04-01-2003 at 09:21 PM.

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