avoiding heat warping......a call for your collective wisdom

[ampedtech]

Howdy kids hope all are well

I have a chunk of 1/4" plate that is 32" x 16"

to stiffen this plate I plan to weld some parallel flat bar 1" x1/8" x 16" along the 16" direction of the plate. The flat bar will be positioned and welded so that the 1" side will be perpendicular to the 1/4" plate.

These stiffeners will be equal spaced.

My concern is that I will warp the plate.


What can I do to minimize warping?
stiff.jpg

[aametalmaster]

Yup you are going to warp it toward the welded strips. How much weld do you need?...Bob

[Nathan128]

Stager welds , jump all around clamp it down real good and /or weld it on aluminum to draw lots of heat away. Those will all help

[ampedtech]

I do not think I need much of a weld. My goal is to minimize flexing along the 16" direction. Perhaps 4 to 5 1/2" beads along each side of the 1/8" x 16 flat. That is most likely overkill. And I am thinking mig.

[Cgotto6]

More shorter welds, like 1/2", cooling with air between each weld. Clamp down firmly to known flat surface

[arc]

also if you are clamping it down, leave it clamped down and heat the whole piece evenly with torch and let cool down after should normalize all the stress from the weld beads. i know this is very time consuming but some times required if part is to be as strait as it was be for... or if this will not work for you then small beads (ie 1") long and skipping around will put much less stress on it. i never liked compressed air for cooling as well if it is a part that may crack this will not help as you cool the beads too fast for the grain structure to form correctly and may crack or fracture.

[Cgotto6]

Yes arc, I should have said that. I have done it on non critical welds to speed up the process.

[go2building]

How many bars? You could per crown the plate by clamping it down with some spacer bars on the opposite side you are welding the 1" bars. If you clamp it to a flat surface it will still warp. As stated, do not air cool with compressed air it's just not a good idea weather it's critical or not!

[MMW]

1-Use a pc. of thicker plate that will be strong enough without welding stifeners on it. Maybe 1/2" thick? No welding = no warping.

2-Clamp it flat, weld it up & straighten it after it cools. Depending on how much weld you put it may bow in both directions.

Edit 3 - Use thicker stiffeners and less of them.

What are you trying to accomplish? 1/8x1 isn't exactly robust for stiffening.

[Helios]

I would figure out how strong/stiff the finished product needs to be, and go from there.

The less you weld on it, the less it's going to warp.

For a 16" long stiffener, I think I'd try to get away with maybe four 3/8" long tacks 4" on center, and allow everything to cool off / equalize as much as possible between each tack weld.

If you find that you're getting a crown on the top (opposite side from where you're welding) halfway through, I might run a bead on the top side to pull it back straight (or even convex) before finishing the welding on the stiffener side (which will pull it back). Then grind off the bead on the top side after you're all done.

If you run into problems, Google "flame bending" (which can also be done with a welding machine).