October 21, 2026 · Indumor
It is Friday afternoon and the beam is done. Thirteen feet of web and flanges welded up, even beads, everything square when it was tacked that morning. But when it is set on the trestles to be measured, the flange is no longer at ninety degrees and the beam has a bow you can see with the naked eye. Nobody did anything wrong, apparently. What happened has a name: welding distortion.
Weld metal goes down molten and shrinks as it cools. The metal around it heated up, expanded and was held back by the cold material around it; when everything cools, that shrinkage pulls on the part. Depending on where the weld is, the part gets shorter, bows or closes its angle: a fillet on one side pulls the angle closed toward that side, and if the welds are concentrated on one flange, the beam shortens on that side and bows. The more heat goes in, the more it moves.
Distortion is not eliminated; it is managed. Parts are preset with a camber or an opposing angle, so shrinkage leaves them straight. They are clamped or held in fixtures, and well tacked before welding. Welding is balanced, alternating sides and in short back-stepped segments. Sequence counts too: the joints that shrink most go first, working from the center out toward the free ends. And nobody over-welds: a fillet bigger than the drawing calls for is not needed, but it adds heat and distortion. An ounce of prevention beats a ton of straightening: flame or press straightening can be done, but it costs hours and does not always leave the part as it was.
In one line: a straight part is decided before the arc is struck. If your parts keep warping, send us the drawing and we will build them at Indumor, with the welding planned from the fit-up.
Send us the drawing and we will tell you how to fit them up so they come out straight.
© Indumor 2010–2026 — Industrial steel fabrication, Córdoba, Argentina
