Hello All, I'm new to welding and am trying to shorten the learning curve on the effects of heat and managing heat/warping.
I've been welding together 1/8" steel scrap to make a lower shelf panel for my table. I have 2.5" wide strips and 1X2" rectangles that I'm welding together (see photo). The first part I made was two of the strips with three of the rectangles between. I tacked it together then went back and welded all of the top side welds without any significant pauses. The piece bowed up from the table about 1/2" as it cooled. Piece was only 24" long. Assumedly this was due to the heat. I clamped down (i.e., in the vertical plane) the next few pieces, took pauses between welds and spritzed them with water after each weld to try to draw off heat. Those pieces have ended up much more flat. On one piece the 1X2" rectangles each retracted up a few degrees after they cooled and I had to bend them. Is this common? How does one minimize heat warpage? Does clamping things help or does it just hold off the inevitable? Should I be pausing to let heat dissipate between welds on this project? Any and all wisdom is welcome.
In case it matters, I was using flux-core wire in an Esab EM210 (220 plug) with the recommended settings.
I would say it is fairly common if you don't constrain in the z-axis (up-down) in the middle where it had a degree of freedom (clamping together does not remove the degree of freedome, only if you clamped to something relatively immovable). Even if you let the heat dissipate, the effect of the welding is cumulative because each successive tack-weld/bead will still contract as it cools, whether it cools naturally or if you artificially dissipate/wick out the heat. And you can't arc weld without heat to create the tack/bead in the first place, so the distortion from weld bead contraction is inevitable, unless you either completely constrain the part in 3-axis and/or induce pre-welding stress in the opposite direction, so that the weld bead contraction pulls it flat in the end.
Thanks Zod and welcome to the planet. My assumption was that the clamping was the least essential of my attempts to minimize warping. Sounds like if you're going to put X degrees of heat into a piece, it doesn't matter if you do it over 60 seconds or 90 minutes. Heck, maybe it's better to get it all welded together before it starts warping? I guess that's good, though my garage smoke detector will not be happy.
Most of my previous clamping has been for gluing woodworking projects. I've been kinda surprised how little clamping I see in the YouTube videos that constitute 99% of my welding education to date. They often just use a grasshopper clamp, but maybe they're working with thicker material.
Distortion is a welding fact of life, but it gets pretty intuitive after a while.
If you search for this topic it's been covered to death but the quick run down is to minimize heat input (weld time. weld size, number of welds), balance the distortion (match welds on other side,season/grind to taste), and pre bend/positioning so that the shrinkage is pre-accounted for. Good fitup also helps.
In your case I would match the top welds on the underside (since they won't ever be seen and don't need to be ground), and use your friendly neighborhood hammer to scare the rest of the shelf straight.
Lookup heat shrinking and it'll give you a great understanding. If you don't have a torch you can use welds in the same manner.
I have 5/8 thick cold rolled steel slats for my fab table, whenever they get bent down over time from hammering or just daily use, I weld a couple beads across the part that is the most convex, and I grind them down, and it pulls it flat again. That just shows you how much warpage heat can cause, also don't forget heat from grinding can do the same thing, and tubing warps in the opposite direction sometimes.
You're conclusion about welding slowly or all at once having the same outcome is incorrect, sometimes you have to weld little 1/2" stitches, and jump around to avoid getting too hot,
Don't "spritz" water on anything you are welding unless you want the metal to MOVE, a lot. Clamping, minimizing heat input, properly sequencing your welds (stitch welds, direction of the weld, etc.) and not over-welding are the keys to minimizing warping. Not every joint requires a full weld. And as mentioned search on Farmersamm's tutorials on heat shrinking. Heat shrinking is the tactical use of warping to undo or counter act an undesirable warp.
1/8 inch thick metal is more like sheet than plate. Go watch some videos of how car restorers weld auto body panels if you want to see some real warping and get some ideas on how to handle it.
The other thing you could do is braze those pieces instead of welding them. If you have an oxy-acetylene torch, that makes it easy and cheap to do. If not, you can use your ESAB EM210 with silicon bronze MIG wire and Argon shielding gas to braze it that way. Brazing puts a lot less heat into the work. You will eventually need argon if you want to TIG weld or MIG aluminum. But the bottle isn't going to be cheap, and pure argon can't be used to MIG weld steel.
Tack it up flat. Put a 1/2" spacer in the middle to raise the center of it. Clamp al 4 corners to the table. Weld it up, one joint here, move to other side weld a joint, skip around until all are welded. Let it cool down, pop the clamps & see where you are. If you are close to flat then next time you will remember. If it is not flat you will know to add or subtract pre-bend clearances...Ahh - welding is a learning experience!
You don't need to weld everything continuously. Beginning welders love to weld and weld and weld. When I'm instructing beginners, I have them do projects where they learn to tack.
When I was an apprentice Pipefitter, we were prefabbing pipe and fittings on the ground. This was 8'',10'', and 12'' pipe only tacked, 4 or 8 tacks depending on size. These were rigged to the roof of a high rise before the tower crane was coming down. I couldn't believe they would hold together when bundled up. When you're going up 50 stories, you don't rig one piece at a time. I was amazed to see those bundled together going up with only tacks.
Do a search for videos on tack strength. I know there were some posted before on weldingweb. When you know what you're doing, tacking those pieces on is all that's needed.
You can do a weld bend test too to see how your tacks and welds holdup. As you gain experience, you'll gain confidence in your welding. Keep at it.
You don't need to weld everything continuously. Beginning welders love to weld and weld and weld. When I'm instructing beginners, I have them do projects where they learn to tack.
When I was an apprentice Pipefitter, we were prefabbing pipe and fittings on the ground. This was 8'',10'', and 12'' pipe only tacked, 4 or 8 tacks depending on size. These were rigged to the roof of a high rise before the tower crane was coming down. I couldn't believe they would hold together when bundled up. When you're going up 50 stories, you don't rig one piece at a time. I was amazed to see those bundled together going up with only tacks.
Do a search for videos on tack strength. I know there were some posted before on weldingweb. When you know what you're doing, tacking those pieces on is all that's needed.
You can do a weld bend test too to see how your tacks and welds holdup. As you gain experience, you'll gain confidence in your welding. Keep at it.
Good point about beginners liking to weld and weld, lol, once you get a nice head started you don't want to stop, I remember doing the same thing 11 years ago and my boss getting upset with me for warping the stainless plate I was welding.
Thanks again everyone. After I slowed down and clamped everything my pieces came out muuuuch flatter. All the top welds are done. There's a slight warp but it sits perfectly in the angle-iron bracket. I wondered if I'd have to weld a piece of angle iron on the bottom side for reinforcement but it seems plenty stiff. Fingers crossed that it won't warp too much when I weld on the bottom side. As an aside, spare a thought for the beginning hobbyist welder. We won't get any better by not welding both sides of every joint! Right now I'm grinding and blending the top welds. That's a whole other learning process. . .
We won't get any better by not welding both sides of every joint!
I am not sure I agree with this. No offense, but unless you learn to cure that undercut/lack of fusion in your welds, you aren't learning anything by making the same mistake over and over again. Knowing how much to weld is also part of the learning. If you want to get in some serious seat time and repetitions, you should be padding beads on plate, not working on actual projects. You also need to practice with intention and make each weld a little better than the previous one ( I know, I know, Jody always says this in his videos, but its true). If you keep getting undercut and lack of fusion, you need to stop and figure out what you are doing wrong and try a few different things to correct it.
I agree with Louie not agreeing with the double-sided welding. There's been plenty of times I've said to myself, "Why TF did I weld this so much/on both sides!?!?!?". Then I have to break out alllll my amazing grinders
I agree with Louie not agreeing with the double-sided welding. There's been plenty of times I've said to myself, "Why TF did I weld this so much/on both sides!?!?!?". Then I have to break out alllll my amazing grinders
I also have a couple amazing grinders to fix ME. I call some of them kids and hand them grinders but still.
I haven't built anything I can't throw away. Perfection is the journey.
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Originally Posted by BD1
