Keeping large weldments from warping....

[Squatch]

I've got a simple but heavy project coming up in the next couple weeks. It's a 4'X8' sheet of 1" mild steel plate cut into a sheet of 3'X8' and 1'X8' (minus the kerf).The 1' width will get placed at 90* to the other along its cut line and welded back.

What can I do to keep this from distorting when it's welded? We'll be welding it with dual shielded Mig.

It will have some 4"X6"X.375"wall rectangular tubing welded onto the 3' wide sections that should help, but I know that it's still going to develop a lot of stress while welding that seam.

I've welded a lot, but nothing that compares to this in scale so I don't have any information to run with.


Thanks,

 

[AKnate]

Would take a shitload of heat to warp 1" plate.

 

[Squatch]

Would take a shitload of heat to warp 1" plate.

Not in my experience.

We built some robot stands a while back with the top plate being 1.5" thick and 42" square and they puckered up near a quarter of an inch in the center of the plate after welding a 32" diameter piece of tube on them for the vertical section.

Making one long weld down the length makes me think it's going to try to canoe like hell.

 

[SomeGuy]

Assume you're going to fillet out the joint right and weld from both sides? If so, tacks first, maybe weld in some supports that can be cut off later (like some 45 tubes to keep the 1 foot chunk square), then multiple passes alternating sides and ends in short few inch chunks. Preheat wouldn't hurt either to get better penetration.

Can't say I've ever done something this size before, so just general best practices for keeping stuff from warping...take it for what it's worth.

 

[ThePanzerFuhrer]

Learn how to flame straighten. If you put any type of weld thats comparable to the parent 1” it’s gonna canoe. Best thing is short runs skipping around a ton but that’s at least a 6 if not 10 pass bead to give that joint any strength.

Good luck

 

[Gravy]

If your beveling and full pening, it will warp no matter what you do.

You need to back bend while your welding. Basically if your welding one side bend it the opposite. Meet in the middle (flat)

Similar to taking a weld test except you don't want it to warp like a weld test

 

[total newb]

Tack gussets and pay attention to the deflection as you weld.

Weld shrinks and pulls. You start leaning one way, weld the side that it needs to go.

Small tacks/welds till you get fully fited

 

[Squatch]

I should have added images yesterday. This is one of the sections we'll be building to add a 24' long "railing" to the edge of a 30" tall concrete dock where forklifts have to dump Rora-hoppers full of scrap.

There will be web gussets between the upright tubing and the weld-seam that I don't have represented here, and the plates will be anchored down to a heavy concrete pad.

I'm still waiting for our Safety Contractor to spec out the height so they're drawn taller than I expect they'll be, but everything else it to scale.

 

[arse_sidewards]

Bolt all that shit to the pad before you weld.

 

[BDK]

Can you bolt it in place, then weld it?

 

[Gravy]

Go with an open corner weld. Maybe see if there is someone local that can bend that capacity.

 

[Firstram]

Bolt it down then weld it x 3

 

[Opiebennett]

Can you form the plate? Welding time is expensive - even $1000 for one 90* bend in a brake with capacity would be cheaper than welding it in any sort of an actual welding program...

Otherwise - total newb and ThePanzerFuhrer are on point - need to start out with the angle less than 90* - like 80* or 82* and have the weld pull it to straight. It takes testing to find out how much weld size pulls how much. Then after you're done, use heat to flame straighten to make up for how you guessed wrong.

Your images are setup for a significantly less than 100% efficient joint. What is the goal of using 1" plate? What strength requirements do you have from this weld? Reducing weld size reduces shrinkage / warp if you can get away with it.

 

[ThePanzerFuhrer]

Yeah that’s a no brainer get it bent. There should be someone near you that can bend 8’ of 1”.

 

[Landslide]

Not in my experience.

We built some robot stands a while back with the top plate being 1.5" thick and 42" square and they puckered up near a quarter of an inch in the center of the plate after welding a 32" diameter piece of tube on them for the vertical section.

Making one long weld down the length makes me think it's going to try to canoe like hell.

I welded up a bunch of robot stands from 1” up to 2.5” thick. I would break my welds down in sections, a pass here and then a pass in another area. It’ll still pull on you tho

 

[AKnate]

Not in my experience.

We built some robot stands a while back with the top plate being 1.5" thick and 42" square and they puckered up near a quarter of an inch in the center of the plate after welding a 32" diameter piece of tube on them for the vertical section.

Making one long weld down the length makes me think it's going to try to canoe like hell.

Interesting. I don't often work with that thick where warping matters much.

Did have 1/2" that I added 2 pieces of 1/4" on each side warp. I straighted it by torch heating.
Have done that on bent cylinder rods too, probably not ideal with the chrome though.

 

[arse_sidewards]

Can you form the plate? Welding time is expensive - even $1000 for one 90* bend in a brake with capacity would be cheaper than welding it in any sort of an actual welding program...

Unless the maintenance dude who'll weld it is salaried.

Your images are setup for a significantly less than 100% efficient joint.

Also this

 

[SomeGuyFromOlympia]

I welded up a bunch of robot stands from 1” up to 2.5” thick. I would break my welds down in sections, a pass here and then a pass in another area. It’ll still pull on you tho

This
I weld 1"+ daily

You can bolt it, welt it, tack it, but it still will move
it boils down to heat management and paying attention to it
I typically will tack shit together with that in mind and start crooked, letting the heat pull it strait, adjust on the fly as needed

 

[total newb]

I should have added images yesterday. This is one of the sections we'll be building to add a 24' long "railing" to the edge of a 30" tall concrete dock where forklifts have to dump Rora-hoppers full of scrap.

There will be web gussets between the upright tubing and the weld-seam that I don't have represented here, and the plates will be anchored down to a heavy concrete pad.

I'm still waiting for our Safety Contractor to spec out the height so they're drawn taller than I expect they'll be, but everything else it to scale.

If forklifts are gona bump that someones gona die. And you can use that to help you.

Add 2 strong backs to it that tie in the lower plate if you expect it to ever take a load.

 

[carslut]

pulse with spray transfer mig has helped me not see as much distortion vs. OG short circuit mig on thick material.

 

[Squatch]

Assume you're going to fillet out the joint right and weld from both sides?

No, it'll be setup with a 1/8"-3/16" gap and single pass welded from the inside of the joint initially, then likely get three passes on the outside of the joint to finish it out.

Learn how to flame straighten.

I have played with this before on my own equipment, but I'm not sure we have the hardware or knowledge here to do it on plate this thick.

We've got a standard Victor torch set and have a long rosebud, but that's a LOT of mass.

Can you form the plate? Welding time is expensive - even $1000 for one 90* bend in a brake with capacity would be cheaper than welding it in any sort of an actual welding program...

I'll dig into this. There's a shop an hour north of us that may be able to do it.

 

[Squatch]

If forklifts are gona bump that someones gona die. And you can use that to help you.

Add 2 strong backs to it that tie in the lower plate if you expect it to ever take a load.

It's going to get some vertical webbing there. That's why I left a few inches between the edge and the back of the tubing.

I just have those hidden on the model here.

 

[Squatch]

...Your images are setup for a significantly less than 100% efficient joint. What is the goal of using 1" plate? What strength requirements do you have from this weld? Reducing weld size reduces shrinkage / warp if you can get away with it.

I skipped answering your other questions accidentally.

The joint strength requirements are minimal, hence the half-lap corner joint. I thought that maybe that would help the warping issue if we weld it from the backside first, then the front. Also, it's less overall weld volume.

The only real force the seam will see is when some dumbass gets a fork under it and tries to lift it unknowingly, of if it's ever hit hard enough to shear the anchors and scoot the entire assembly.

For the plate choice. Our biggest lift that uses this dock is about 24" from the face of the forks to the centerline of the drive tires and I want plate under the drive tires to help transfer that energy up into the lift instead of just shock loading the concrete underneath when they bump into the rail.


Seat of the pants engineering led me to going with 1" plate strictly due to "I feel" like that was a minimum acceptable thickness.

 

[Steve300xcw]

You can chase it around a bit by just stitching it in and paying attention to which way you need it to pull.

Also, expecially this time of year. Give that thing a preheat before you go welding on it. Watching your first pass, crack down the middle will piss you off

 

[Muckin_Slusher]

Bent might require some chipping out of the concrete to clear the radius of the bend.

So would the weld on the inside of the corner.

 

[mobil1syn]

does it have to be fully welded out?