Weld penetration and wetting

  1. SteScouse

    SteScouse Forum Supporter

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    Yeah, ok, title is an invite to a lot of poor jokes, and yes I'm guilty as anyone else cos I've thought of lots already

    But its a serious question re welding, you know that process this forum is about...

    Anyway, I'm asking can you judge the depth of a welds penetration from the apparent diameter or visible spread of wetting during the weld?

    I got to thinking wider the visible wetting, deeper the actual penetration is likely to be. Tho material thickness needs to be taken into account too to avoid blowing thru.

    Sensible answers welcome from anyone with alot of welding experience, amateur or pro :clapping:
     
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  2. Yamhon

    Yamhon Member

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    My guess would be generally no, because there are so many variables. Thickness of material, joint design, tilt angle, slope angle, manipulation, arc length, etc can all impact penetration; so you may end up reading into a puddle that you've achieved x penetration, when it may just look that way because of other factors and your penetration is closer to y.
     
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  3. SteScouse

    SteScouse Forum Supporter

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    I do mention material thickness above mate, and honestly no offense but I'm after opinion of guys with lots of project experience or professionals re this question

    And I'm really not trying to insult you, but yet to see any welding you've done
     
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  4. TechnicAl

    TechnicAl Member

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    The simple answer is no

    The shape and size of the visible weld does not give any valuable indication of the depth of penetration. You really need to cut, polish and etch to see the actual weld shape.
     
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  5. Yamhon

    Yamhon Member

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    I've shared photos in relevant threads. Not an insulting question; if you want to see some welding I've done, just ask and I can share what I have photos of.
     
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  6. anto44

    anto44 Member

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    Amateur opinion here, yes you can tell penetration by looking at the weld pool and the way it wets in but it comes from experience, the more experience you have the more accurately you can tell.
    Butt joints On stainless pipe that's purged I can tell just by the look of the weld pool if I'm getting full penetration or not, on other stuff I'm not as experienced with I will have a good idea of penetration level.
     
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  7. The_Yellow_Ardvark

    The_Yellow_Ardvark Member

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    @SteScouse

    A good question.
    One I will be following as it is something I was going to be asking in the New Year.
    Thanks.
     
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  8. SteScouse

    SteScouse Forum Supporter

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    Cheers Al, but I'm not talking so much about the actual weld puddle as the wetting that surrounds the puddle. That area of metal between the puddle and the area that appears unaffected.

    Realise i may be over thinking this thats why I'm after experienced opinions like yours

    And jus not seen your pictures of welds yet Yamhon, point me in the right direction..
     
  9. TechnicAl

    TechnicAl Member

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    Im not really sure what you mean.

    Sometimes you can get penetration everywhere except at the junction of the 2 plates (standing fillet). In such cases the undercut will be an indicator but it could still be fused without undercut.

    Personally, I think the only way you can judge it, without cutting and etching, is if its the umpteenth copy of a previous weld that was cut and etched...
     
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  10. mtt.tr

    mtt.tr Member

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    Think of a fillet, it can look good but you could have nothing in the corner
     
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  11. TechnicAl

    TechnicAl Member

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    exactly......and the only way to tell is to cut and etch
     
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  12. SteScouse

    SteScouse Forum Supporter

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    I understand Al

    Guess best way i can describe it is immediately outside of the actual molten weld puddle is an area that looks kind of wet and somehow is a boundary between moltem puddle and unaffected base metal. When weld is finished this is usually area marked by discolouration

    And my amateur mind is wondering if that area increases in size does it indicate deeper penetration under the molten weld puddle, which is in fact a separate area

    Sorry if i am describing this badly, but it is a genuine question, i just want to learn
     
  13. TechnicAl

    TechnicAl Member

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    Right, I think I know what you mean......Again the answer is no...In fact, I would say that the bigger that is the LESS likely youve got pen at the corner....It could indicate wrong torch angle or a badly directed arc.
     
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  14. SteScouse

    SteScouse Forum Supporter

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    I understand this is only 100% way to check, and in industry a sacrificial cut and etch makes a lot of sense

    But for a one off DIY weld mostly not practical, which i why I'd lke to learn much as possible how to judge strength and penetration during the weld process

    But if truth is thats not really possible then I've learned something anyway, and I'm grateful :thumbup:
     
  15. SteScouse

    SteScouse Forum Supporter

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    Excellent, thats exactly what I'm after. And it makes sense too as more heat going sideways than going down.

    Fantastic, thanks Al
     
  16. SteScouse

    SteScouse Forum Supporter

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    :laughing: chuffed
     
  17. TechnicAl

    TechnicAl Member

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    Looking at the back side of the plate maybe more helpful.....If its obviously been glowing probably wont 100% guarantee pen but if its hardly affected theres a very good chance you havent penetrated.....a bit of a negative but if its a trial you might get a good idea.
     
  18. SteScouse

    SteScouse Forum Supporter

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    Most times on thin stuff i can tell by flipping over how penetration went

    But last year stick welded some 10mm thick fencing brackets up, total newbie at that time, done alot more since

    Thats the sort of thing more concerned about. Dont get me wrong, they still doing their job. And I'd not be able to break them or want to be hit with them lol

    Guess what I'm chasing is more confidence in welds i do, tho thankfully nothing has failed me yet :welder:
     
  19. TechnicAl

    TechnicAl Member

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    thats the acid test
     
  20. SteScouse

    SteScouse Forum Supporter

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    It is, which is why i wont touch owt safety critical. No trailers or ladders lol

    Thank you Al, really appreciate your time tonight :thumbup:
     
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