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Thread: Porosity, Why?

  1. #11
    Join Date
    Oct 2007
    Location
    W. KY
    Posts
    28

    Default

    What size cup would you recommend? I have to go to town Monday to get my bottle filled anyway so i might as well pick one up.


    Thanks, Justin

  2. #12
    Join Date
    Dec 2007
    Location
    alabama
    Posts
    746

    Default

    I suggest a number 10 with the large gas lens.
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  3. #13

    Default

    Porosity comes from contaminates! Ether the contaminates are getting into the weld from lack of shielding gas or some other contaminate (oil, rust, mill scale, paint, ect). If you rule out the "other contaminates" then it is a lack of or improper shielding gas. And as it has been stated wind could be blowing away your shielding gas.

  4. #14
    Join Date
    May 2008
    Location
    Troy, MI
    Posts
    335

    Default

    After you have eliminated all of the root causes mentioned in this post there is still one additional cause of porosity, which is holding too long of an arc. The weld would have porosity that looked the same as porosity caused by improper shielding.

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  5. #15
    Join Date
    Oct 2007
    Location
    W. KY
    Posts
    28

    Default

    Don you may have something. How long should my arc be? I picked some new tungston today but they didn't have a #10 nozzle to replace my #7. Tomorrow I'm going to finish my slide hammer, I'll shorten my arc up some and see if it helps.

    Thanks, Justin

  6. #16
    Join Date
    Nov 2006
    Location
    toronto,ontario
    Posts
    90

    Default porosity problem

    hi friend ,if youve covered all your other bases, my only other thought is that carbon steel(if thats what your material is) tends to do that when it is overheated,everything else in check(gas coverage etc0 ALSO ARE you keeping the gas post flo going after you stop your arc?

  7. #17
    Join Date
    Oct 2007
    Location
    W. KY
    Posts
    28

    Default

    I forget where the post flow is set but yes I'm using it. I have the welder set at 155 amps, after the weld is started I ease up on the pedal and continue. The rods are 3/32 and 3/32 tungston, argon set on 20 cfm with a #7 cup. Like I've said I'm trying to learn this process, but sometime I get frustrated and pick up my mig or switch back to stick. It's most likely a combination of errors on my part, I have a lot to learn.
    Thanks to everyone for the suggestions.

    Justin

  8. #18
    Join Date
    Sep 2008
    Location
    SE.Mo.
    Posts
    117

    Default hmm

    I may have missed it but how thick is the base metal, so far everyone has touched all the other bases, all else fails id say the heck with tiggin it go od school Oxy weld it no need for shielding gas and so much easier to control the heat

  9. #19
    Join Date
    Oct 2005
    Location
    British Columbia
    Posts
    242

    Default justinp61

    Being a newbie, do you know that any stray arc marks are a potential source for porosity. This would include if you happen to scratch start the tungsten into too long an arc, or actually sticking the tungsten to the plate and then breaking away too far, or leaving a stray arc mark after you break off. Slight marks may be harmless but if there is any sign of pitting or a crater, then that area has to be totally ground out. You shouldn't weld over a bad 'pit' and hope to burn it out. Most of the time it will develop into visable porosity and if you do happen to bury it, then you'll never know the quality of your weld. I mention this because there appears to be an example on the extreme left of your picture. The tan smokey residue suggests an excessive long arc has happened and there looks like a crater in the first metal deposit. If there were similar marks further along they could have been your problem. Then again I could be totally off base.
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