Bending Welded Aluminum

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Hello AllI'm new to this site and it looks like lots of good info. I have a question I need some help on.  I am rolling some 3003 1/8 thick al into a 9" tube.  I need a 36" X 36" piece to make what I need.  I want to weld a 12" X 36" piece onto the 24" X 36" inch piece to get the size I need.I would like to weld it while its flat than weld 2 rolled pieces together.  Will it affect the welds if I roll it after I've welded it or would it be better to wait?I am using the TIG process, straight Argon, 4043 filler rod (I think).  I need to grind this weld flat at some point.  This is another reason for welding prior to rolling.Any thoughts or comments?Thanks in advance for any helpRick
Reply:Why do you need a 9" pipe? That's an odd size. But whatever. have you thought of using a 10" pipe and cutting a 1" strip out of it and welding it back together? I think that's how I would try to do that job.And remember tubing is measured O.D. and pipe is measured I.D.Think of a handrail as tubing and a pipe has something flowing through the inside. Different sizes for different applications. And wall thickness is a whole another topic that I don't feel like getting into right now. I only smoke when I am on fire!
Reply:According to Alcotec's aluminum filler rod selection chart:http://www.alcotec.com/us/en/support...on_Chart-2.pdf... 1100 filler rod would give you the most ductile weld deposit to join 3003 parent metals.  4043 would give a deposit that is a little less ductile, but a little stronger.1100 is harder to find than 4043, but it is available if you look.  (I've got some 1/16" 1100 filler.)Weld both sides and grind both flat, and either filler would hold up through your rolling operation, I would think.
Reply:Jakeru wins with perfect info. Send him his prize for the day!!And then, after so much work...... you have it in your hand, and you look over to your side...... and the runner has run off. Leaving you holding the prize, wondering when the runner will return.
Reply:Thanks for the info.  I am going to try and find some 1100 rod.  Strength is not a big a deal as ductile. Diameter of this tube was not critical.  My material is 36" long, what ever size that rolls up into is fine.  Probably closer to 11.46" diameter is I'm doing the math right.Main thing was I wanted to weld in position as much as possible.  I am a first year TIG student.Rick
Reply:Well so much for the 1100 rod.  My supplier found 3 lb in a wharehouse in Chicago.  That was it.Probably just go with the 4053 rod on the 3003 aluminum.  No strength required.I do appreciate the education though.ThanksRick
Reply:The welded area will have a different contour than the unwelded area, post forming. It will likely be a positive peaking issue. Even with grinding to parent material thickness, it will form at a different rate than the parent material.Two turn tables and a microphone.
Reply:Originally Posted by PangeaThe welded area will have a different contour than the unwelded area, post forming. It will likely be a positive peaking issue. Even with grinding to parent material thickness, it will form at a different rate than the parent material.
Reply:The weld seam may not be as stiff as the parent metal, causing it to peak somewhat when you pass it through the rollers. This will leave you with a slightly eccentric tube. You will be able to work that out once your tube is welded up.
Reply:Originally Posted by Pro-FabThe weld seam may not be as stiff as the parent metal, causing it to peak somewhat when you pass it through the rollers. This will leave you with a slightly eccentric tube. You will be able to work that out once your tube is welded up.
Reply:The softer weld area will not form at the same rate as the harder parent material. It will want to bend faster than the original sheet. You might be able to adjust the contour after it is rolled by using a rounded anvil and a dead blow hammer or some other mechanical process but i doubt that rolling will get you the circle that you desire.Two turn tables and a microphone.
Reply:You'll have a much more consistent part if the weld runs around the finished pipe instead of along its length.  -jimDynasty 300DXSmith He/Ar gas mixerMM350PHobart Handler 120Smith LW7, MW5, AW1A