Crack appears in weld as it cools
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  1. #1

    Crack appears in weld as it cools

    Folks,

    I'm a novice, but am having fun learning. Sometimes - too often - when I weld (with oxy-acetylene) a butt joint the weld looks OK, but as it cools a crack will suddenly appear along the length of the weld. Today this happened as I welded two 3/16" thick 2"x2" angle irons 18 inches long together (welding them together to form a U-channel). I don't bevel the edges - just butt them together.

    Any ideas what I'm doing wrong?

    Thanks,
    Jack

  2. #2
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    Re: Crack appears in weld as it cools

    Probably not enough weld since you have no bevel. The strength of the steel moving as it cools is stronger then the weld.

  3. #3
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    Re: Crack appears in weld as it cools

    Try preheating your workpiece a little with the torch before u start welding. Take it slow. A pic would help in diagnosis

  4. #4
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    Re: Crack appears in weld as it cools

    Hot cracking takes place at temperatures over 1000 deg F and occurs almost immediately when the weld solidifies. There are three common types of hot cracking: segregation, bead shape and crater cracking. Segregation cracking is a type of centerline cracking, which (as its name implies) occurs through the center of the weld. It results when low melting point elements are concentrated in the center of the weld after it hardens. It is common when welding metals that have higher sulfur and phosphorous content, ones with zinc plating or galvanized coatings, and on materials that have been painted or primed.

    There are several options to help prevent this type of cracking:

    (1) Order steels with low residual phosphorous and sulfur (less than 0.05 percent), if possible.
    (2) Reduce heat input during welding, which lessens the time for segregation to occur.
    (3) Modify the joint design so that depth-to-width ratio is not too great or too small.
    (4) Make welds with more throat thickness or that are less concave.

    I would clean back the weld area to bright metal and include a slight bevel, turn the heat down (amps) basically any of the above 4

    Hope that helps
    Last edited by Gerry1964; 12-29-2012 at 02:42 PM.


  5. #5
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    Re: Crack appears in weld as it cools

    Quote Originally Posted by Gerry1964 View Post

    I would clean back the weld area to bright metal and include a slight bevel, turn the heat down (amps) basically any of the above 4

    Hope that helps
    How do you turn down the amps on OA

    Cheers Andrew

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    Re: Crack appears in weld as it cools

    Quote Originally Posted by FODFA View Post
    How do you turn down the amps on OA

    Cheers Andrew
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  7. #7
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    Re: Crack appears in weld as it cools

    Hmmmmmmm OA......I would guess your not adding enough filler or like mentioned
    there is some plating present? Pics would help



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  8. #8
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    Re: Crack appears in weld as it cools

    Angle iron? Grind the mill scale off first. The carbon in the mill scale can make things brittle.
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  9. #9
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    Re: Crack appears in weld as it cools

    This angle you have isn't from a bed frame is it?
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  10. #10

    Re: Crack appears in weld as it cools

    Thanks, folks. This is great information. I've attached a pic. The angle iron is just stock from Tractor Supply.

    Alas, by uploading this picture you'll see just how poor my welding skills are!

    Jack
    Attached Images Attached Images  

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    Re: Crack appears in weld as it cools

    Quote Originally Posted by zeke View Post
    This angle you have isn't from a bed frame is it?
    I thought bed frames were friction welded
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    Re: Crack appears in weld as it cools

    Quote Originally Posted by zeke View Post
    This angle you have isn't from a bed frame is it?
    Good question bed frame angle is a crap shoot
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  13. #13
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    Re: Crack appears in weld as it cools

    More filler please
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  14. #14
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    Re: Crack appears in weld as it cools

    Quote Originally Posted by FODFA View Post
    How do you turn down the amps on OA

    Cheers Andrew
    Apologies i didn't read it correctly


  15. #15
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    Re: Crack appears in weld as it cools

    That's nice that you've tried a butt joint, but you haven't mastered puddling with o.a.. Cut some coupons and practice puddling. Do not play with filler rod until you've achieved something close to perfection pushing the puddle on coupons. Or waste your time.

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    Re: Crack appears in weld as it cools

    Quote Originally Posted by zeke View Post
    This angle you have isn't from a bed frame is it?
    This is what I thought of too. I tried welding this crap once and it's so brittle it just hot cracks or breaks off at the weld.
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    Re: Crack appears in weld as it cools

    Quote Originally Posted by DSW View Post
    Don't shuffle your socks on the carpet as much.
    thats funny

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    Re: Crack appears in weld as it cools

    jackganssle

    Every piece of steel I have O/A welded isn't silver when finished.

    It always has pronounced thermal-gradient bands - HAZ.

    In the picture, there appears to be: faint spectral temp. colors - parallel
    with the joint, but not consistent with steel.

    Your coupon look like T6 Aluminum fried with O/A. 6000 series aluminum
    contains iron as a trace alloy; possibly responsible for the faint colors.

    Weldable steels don't behave this way.

    In keeping with: your self acknowledged novice-spirit, can you please have
    the material positively identified by an authority, because;

    I would like to know how you got these results as much as you.


    Opus

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    Re: Crack appears in weld as it cools

    I am with BC, Rkott and the cricket. Number one, need a bit more of a real puddle. Number 2, gotta add filler. Steels tend to lose important properties when joined without filler. The welds look nice, but will crack, and crack and crack.
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  20. #20
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    Re: Crack appears in weld as it cools

    your picture wasn't very clear but from what i could see (as other's have too) you don't have enough filler metal in the joint. try making straight soapstone lines on a piece of flat stock and make practice beads after you get pretty good with that then try joining two pieces together. get a book on oa welding or look online to see what your beads should look like. keep practicing and don't give up.
    i.u.o.e. # 15
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  21. #21

    Re: Crack appears in weld as it cools

    The strength of the steel moving as it cools is stronger then the weld.

  22. #22
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    Re: Crack appears in weld as it cools

    Quote Originally Posted by jackganssle View Post
    Thanks, folks. This is great information. I've attached a pic. The angle iron is just stock from Tractor Supply.

    Alas, by uploading this picture you'll see just how poor my welding skills are!

    Jack
    Like I mentioned before your not adding enough filler....Start there and see what you get.........



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  23. #23
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    Re: Crack appears in weld as it cools

    Don't get discouraged some guys take more time than others just make sure you have GOOD practice because bad habits are hard to get rid of.......



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  24. #24
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    Re: Crack appears in weld as it cools

    Quote Originally Posted by Snuffy View Post
    I thought bed frames were friction welded
    .......and thats why my woman wanted a wooden bed frame......so I can't complain about the lack of friction welds on a steel unit.
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    Re: Crack appears in weld as it cools

    Assuming the material you have is indeed steel, you may want to double check your flame adjustment. How does the puddle behave when you are welding? Is the puddle glossy and well behaved or does it bubble and fizz?

    Others have given good advice above - practice forming and moving a puddle on a flat piece of stock. Taking the time to master this before moving on to actually joining metals is key. Yes, it will take some time but it is the best way to learn about the puddle. While you're learning about the puddle on a plate, be sure to play with different levels of heat and both oxidizing and carbuerizing flames so you get a feel for how each will affect the metal. You will only want to weld with a neutral flame, but its good to see how the different flames influence the molten metal.

    OA welding is a fun process and its what I learned with, still learning actually. There are some good videos on youtube that will show you what the puddle is supposed to look like. Keep after it, it will all click soon and then its smooth sailing!
    Victor OA
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