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metal warping after welding

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  • metal warping after welding

    I am welding 7/8" thin wall stainless square tubing into 21"x57" rectangles with 5" bracing pieces welded in each corner. after welding all 4 sides now curve toward the middle quite a bit, about a 1/2" deflection from straight on the 57" side of the rectangle. i am trying to bend it back out with a screw jack. what is causing the steel to pull in and how would i keep it from doing that?

  • #2
    The trick is minimalize the heat input, so flipping and moving away from the previous weld is necessary.

    I am not sure of the process your using or method of assembly so lets start from the beginning. First, tack the 4 corners two tacks per corner then check square and add a third tack on each corner to lock position. second, weld 1 side of 1 corner then the oposite corner. then flip and weld 1 side of the corners that havn't been welded then weld the second side of the first welds and lastly flip and weld the last two joints.

    This is tricky and patience is a must, I have had similar trouble in Aluminum the thinner the stock the more trouble it can be.

    Good luck


    • #3
      weld joints will shrink and pull the metal in the direction of that contraction... if you weld the opposing side of square tubing right after welding the first side.. it will minimize the distortion..
      also tacking the tube on all sides will help to stabilize the tube before doing the final weld... sounds like you may have done one continious weld all of the way around.. which will put a lot of heat into the tube..all at once.. letting it expand and maximizing distortion... tubing will walk when heated.. you need to learn how to control that.. so it ends up in the same place when finished as when you started.. this was a huge problem in gas welding tube in aircraft fuselages..
      hope this helps

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