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I am building a weldment that is a 1.5 dia .120 wall 1026 DOM tube about 18 long with a channel cut across the tube (perpendicular to the long axis) 3 inches from one end and a ¾ tube welded into the channel so that the small tube is flush with the edge of the larger tube. The weld will be MIG. I am concerned about the 1.5 tube warping, since it will be welded on only one side of the tube. Can I counteract the warp by shrinking the opposite side of the tube with an OA torch? Assuming so, how hot should I make it, full red or beyond? Would it be easier just run a few beads with the MIG on the back side and grind it flush? Will forced cooling help with shrinking? I am thinking an air stream from an air gun (or a spray of water if that would be better).As far as I know, 1026 is low enough carbon content that becoming brittle at the HAZ wont be a problem.thanks,Robert
Reply:Preheating and jigging would be the best method I can think of to prevent warping.
Reply:I have an old website kicking around with examplesLast edited by lotechman; 04-11-2006 at 09:47 PM.
Reply:The tighter the fit the less shrinkage problems you will have. If you end up with gaps you are not alone.Yes, you can use an oxy-acetylene torch to straighten it afterward. Shrinking is done at a red heat. The important point here is to heat the opposite side from your weld to a red heat quickly so that the area surrounding is relatively cool. For something like you describe I would just heat an area on the opposite side until I had a red area about the size of a 25 cent piece. If you want to increase the shrinkage effect you can apply a wet rag or air/water spray in a circle surrounding the red. As the red disappears, chase the edges inward until it is all black. I suspect the first heat suggested will not be enough but it is much easier to repeat the procedure several times rather than overshrink it. Make sure that you weldment is cool to room temperature when checking for straightness. People in their excitement to straighten will check while still hot and shrink the item some more. Believe me I know ALL about this little mistake! |
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发表于 2021-9-1 00:17:18