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I understand that a weld, if done properly, is stronger than the base metal. Does this mean that if you have a part that needs to be formed, the bend can be made along the weld? Or is the weld filler more brittle or have some other material property that would prevent this?

As an example, I have the part in the image below. It is to be formed with bend lines at the green dashed lines. Due to manufacturing limitations, I cannot form the entire part at once, so I have to split it, form it and re-weld it. I can split it anywhere along the length of the part. But, out of curiosity, I'm wondering if I can make a vertical cut on one of the green dashed lines (indicating a bend line), form the parts separately, weld them back together, and make the final bend along the weld joint.

The welding process is TIG. The base metal is 1100 Al, which is welded on both sides with 1100 Al filler.

Flat pattern of formed sheet metal

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  • $\begingroup$ I am not sure what you mean by I can make a vertical cut on one of the green dashed lines (indicating a bend line). could you elaborate? In the mean time, you are right that the material is stronger but sacrifices some of its ductility thus making it more brittle, so you can't safely bend on a weld line. $\endgroup$
    – NMech ♦
    Jan 27, 2021 at 16:16
  • $\begingroup$ @ImDumb - Maybe possible but I would hesitate before taking this route. The weld will anneal the material around it, cooling while fixed in place can add stress, etc. If know you have 2 parts, and you know you have a weld, then design for that. Give the bent part some wings and/or little tabs that go into mating cuts in the other part, which get leverage so the weld doesn't have to be as strong, and help align it too in the setup. $\endgroup$
    – Pete W
    Jan 27, 2021 at 17:36
  • $\begingroup$ @NMech I just meant that, for example the vertical green lines on the screenshot could be used as a layout line for a plasma cutter, angle grinder, etc to split the part in two pieces. I edited the original post; I hope it's a bit more clear. $\endgroup$
    – ImDumb
    Jan 27, 2021 at 17:52
  • $\begingroup$ The 1100 Al is essentially pure aluminum. , so it does not respond to any type of heating or cooling ; unless it is cold worked . $\endgroup$
    – blacksmith37
    Jan 28, 2021 at 1:23

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Depends on base metal, filler metal ( if any ) and weld process and technique. Welds may be weaker or stronger ; more or less ductile than the base metal. No problem with a properly made weld in the right base metal.

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  • $\begingroup$ It's 1100 AL TIG welded on both sides with 1100 AL filler. $\endgroup$
    – ImDumb
    Jan 27, 2021 at 17:57
  • $\begingroup$ @ImDumb It would be best for you to add that info to your question. You can always edit your own question. $\endgroup$
    – Eric S
    Jan 27, 2021 at 19:15
  • $\begingroup$ To quote a fracture mechanics consultant " 1100 Al filler metal has the ductility and strength of bubblegum" . Me-It is stronger than bubble gum , he was just accustomed to working with high strength steels. Don't worry there is nothing you can do to mess up 1100 if you have a sound weld ( not full of porosity). $\endgroup$
    – blacksmith37
    Jan 27, 2021 at 19:50
  • $\begingroup$ @blacksmith37 Well now I'm confused because I have conflicting answers. I will err on the safe side this time and test bending at the weld joint next time. Thanks! $\endgroup$
    – ImDumb
    Jan 27, 2021 at 22:40
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Bend the bits separately then weld them together is one option.

As for welding, bending and forming just take a look on youtube about how some of the old car wings have pieces welded together and are then rolled and stretched to beautiful curves... BUT the experience of some of those guys is phenomenal.

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  • $\begingroup$ That's interesting. Do you have a link? $\endgroup$
    – ImDumb
    Jan 27, 2021 at 17:58
  • $\begingroup$ @ImDumb you need a link to youtube? Look for rolling metal or shaping metal or repairing car wings etc $\endgroup$
    – Solar Mike
    Jan 27, 2021 at 18:18

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