Problem Welding Metal Plate

by Danial R.

My technical staff here in my company recent worked on a 2-inch thick metal plate. While doing heavy welding on it the plate bended from both corners resulting in a potbelly shape from the middle. I was told that that happened because too much welding was done on it at once without letting it cool off...is that correct? Is there anyway I can prevent that from happening? Your help would be greatly appreciated.

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Feb 22, 2015
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Do your homework -- Do diligence is required.
by: Jack Frost from Northern Canada.

From my experience I would suggest that heavy 2-inch thick metal plate should always be double beveled and always welded from both sides if possible to help counter distortion.

Information and welding procedures can also be found and obtained from various Engineering sites and or from vessel and or plate manufacturing shops.

The internet could also be a very helpful tool to research and get required information from.

Do your homework and always practice do diligence.

Sep 17, 2013
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Strong Back
by: Dan

Weld a strong back onto the opposite side your welding on.
A strong back can be heavy duty flat bar or heavy duty Box section.

May 20, 2013
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trial&error
by: jason7

Trial and error! Try it. By the time you figure it out ,you wont have to ask anybody. You will have tried and know exactly what every technique will result in. Because, you have already tried it that way. You cant be 100% sure the job is right, untill you have experienced everything that can go wrong. Goodluck

May 02, 2013
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where to start
by: Anonymous

1.Metal over 3/4 inch thick should be preheated and post heated.
2.A 3/32 rod is too small a diameter rod for 2 inch thick plate.
3.You can back step your welds to help control distortion.
4.Never quench
5.If more than one pass is made, You have to have interpass temperature control.
6.not every manufacturer have the same amperage rating for a given diameter, not all rods are the same.
7.7018 has to be kept warm and dry. they are low hydrogen and pick up moisture, they cannot be left out any longer than 4 hours, or you can get hydrogen underbead cracking.
I could go on and on but I'm a welder not a typist.

Apr 02, 2013
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Bending Plate
by: Stony

Don't know the size of the plate, we always heat the plate or part on these type of projects, it very hard to stop but heating the part from the back keeps almsot and deflection out. Remember the hot rod changes the particles in the iron, so change the other side if posible.

Feb 12, 2013
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Finish Feb. 11th comment
by: Gator1

I was cut off in the middle of a sentence the other day. (THANKS)
I was saying that I don't think there is a problem with the 7018-3/32 rods sticking, since I tried 5 different brands and they are all the same, the problem is that they should have 60-90Amps on them..... That doesn't answer why all companies would have the same amperage on the pkgs. Well at least we know it is the rods, not us since there is more than 1 person with the problem.
Keep on Burning.

Feb 11, 2013
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Sticking 7018 3/32 rods
by: Gator

For the pot belly welder RE: 7018 3/32 rods. I have the same problem with sticking, and I have to turn the amperage up as well. OS, l have bought several types of the same number and size, but they all stick at low amperage. I mostly use 6013 3/32 now, I find them better. I don't think there is a problem

Feb 08, 2013
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bending weld plate
by: gwenda

from my experience, even though it's 2" thick, u still have to cool it down whether it be from quenching in water or just plain waiting for it to cool on its own, which i choose to quench it! then u can wire wheel it and check ur work out! i'm a bit ocd i guess with my welds cause i wire wheel it and keep it clean! oh yeah and maybe even tacking oppisite corners down helps from curling!

Jul 21, 2012
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Create support
by: Joel

Just to buttress what others have said, creating a good support especially at the joint area can help prevent distortion.

Jun 22, 2012
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pot belly welding
by: Gator 1

Put a rock out in your garden and ask how to move it and people cam make it so complicated. The simplist answer can be the best. Like the other people said, weld both ends, then in the middle, then 1/4 then 3/4 then inbetween these. Take your time, let it cool between welds.
I like stick welding, and I have bought 7018 X 3/32 rods that are not supposed to penetrate very deeply and work between 40 and 80 AMP. but I have to turn my welder up on 90 to 105 AMP. to stop them from sticking, Can anyone tell me what is wrong.

Apr 23, 2012
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WELDING TIPS
by: Hilton

there to many things you can do to avoid distortion. 1 reducing the weld volume to avoid overfill and consider the use of intermittent welding.2 minimising the number of welds runs.3shortening the welding time.hope it helps. good luck

Oct 18, 2011
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Good ideas
by: Skibumleo

All good ideas. But you failed to tell us if you are attacking from one side or both. Keep in mind, with different weld approaches come different fitting approaches.

Oct 18, 2011
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Slow down
by: Skibumleo

If you weld plate for to long a time, the welded side begins to shrink. This causes the plate to curl. Try longer pauses be tween beads,alternating shorter staggered beads from one end of the plate to the other. If you antisapate this,'you can fit it by a mulitude of tricks. Adding weight to the ends, adding clamps to secure the weldments, or even exaggerate the two flat plates to form a slightly convex shape before welding, so it will shank and pull itself flat are but a few ways to prep the job. Keep in mind a good welder knows that steel talks back and moves. So make it listen and moveyolkier demands like a well trained dog.

Oct 18, 2011
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Clamping
by: Steve

I think it might be a good idea to try and clamp the metal plate as flat as possible and clamp it as tight as possible to a flat table and leave the clamps on until it is cooled down to room temperature.Another suggestion would be to build some sort of fixture to tightly secure your work so it dosen't have as much of a chance of warping/bending on you.Good Luck,Steve...

Jul 21, 2011
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metal
by: Anonymous

letting it cool is good but you can back bend your met. but you will need a checker table thick enough to hold down will doged down. run rose bud hot down the middle on ther side to relieve stress from you welding to much make pass flip over get it hot let coolso welding temp go for it again using same meth ,

May 13, 2011
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Problem Welding Plate
by: Ron Paskiewicz

Don't know if it was already mentioned but a "Back-Step" technique will surely solve the problem as well as or in addition to a "Strongback."
Best Regards!

May 13, 2011
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Apr 28, 2011
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welding
by: Anonymous

I don't know how much weld you put on it, but it is probally best to tack the ends in center really good, let cool and then proceed.

Apr 18, 2011
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Thick plate warpage prevention
by: TurnNburn1x

I don't claim to be an expert either, but from past experience with heavier plate, especially in the dead of winter time it's best to pre-heat, skip around by breaking the length of the weld into 10 individual stitch welds, and maintaining the preheating at the same time and secondly tack adequit bracing/stiffeners on the back side. Allow to cool naturally or even burying in lime if nessasary to slow the cooling process. Once completely cooled down break the stiffener braces of and you should be good to go. Once again, not an expert, but 20+yrs exp. had to learn something. Hope this helped. TurnNburn1x!!!

Apr 09, 2011
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work it around
by: Michael

For most any weld sitiuation if your working a square type construction where flat plate is welded to beams and you weld all the way around and dont stop its going to warp like crazy.

Take time to make strong backs and tack in.

tack together evenly with small tacks always work a peice in oppisites meaning if you take on one side go directly across and tack other side.
once tacked weld small sections at once staggering
and welding across from each place.

Weld it slow keeping your heat down as much as possible.
If your co worker does weld a peice all the way around and doesnt stop its great fun to watch him freak out when hes done . Lol happened last week
He was freaking . the plate lifted like four inches off the Ibeam . If it does it a small amount you can uasually dog it in with a wedge and temp dog bracket. If not you may have to make stress cuts threw the peak of bow and heat with a torch and hit the back side with a cool damp cloth . warning this type of fix is for advanced fitter welders. use common sense. it can get dangerous if your trying to move warped metal too much . Wedges can fly out like bullets.thats what happened last week . i was working in my area and the apprentice welders wedge came flying over my head like a bullet. He finnally asked a advanced fitter for help and it came out great.

Mar 13, 2011
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read
by: Anonymous

quench your metal so it can cool off then usually isnt a promblem to weld one it again think of wut aluminum is like theres no way you can weld on it again after its been heated up and welded on in that case your metal would disperse,but with wut your usuing would cause it to bend and probably crack n such

Jan 18, 2011
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ya
by: Anonymous

Ya you are right, the heat from where you are welding pulls/contracts the metal. and will cause distortion. Only way to stop that is just not let the metal get so hot.

Jan 15, 2011
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backwards and forgot
by: Anonymous

I think... I think... try to weld it backwards. I'm not so sure how long is your beads but to me, I will try to weld it bit by bit and let it cool off for a while. I will go.... ((>>>>>>>>> this way and start again here >>>>>>((>>... so the heated parts is far from the new weld bead to be. and go again backwards. Time is in your control... and clamps, vices and jigs works too. You're the weldor. Not them. Who? huh?
..weld with a smile..

Sep 16, 2010
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problem of buckling
by: phelippe

i asked my insructor and he told me that there was to much welding done at one time and that you shuold weld cool down and go again. Also clamp it down so that the clamps help stop some of the buckling. Again i'm just starting to learn and all the questions and tips i can get would be really appreciate the help

Jul 31, 2010
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Your problem
by: Andrew Goszkowicz

It is true. There was too much welding on one side at one time. what you should do is spot weld the plate there and then do ice welds on it.

Jul 23, 2010
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BENDED PROBLEM
by: JIM

NEVER GET THE METAL THATIT BENDS THE PLATE, BUT NEXT TIME MAKE A SADDLE FOR IT ONE AT THE TOP AND ONE AT THE BOTTOM. A SADDLE IS A PLATE ABOUT 6 OR 7 INCHES LONG AN RIGHT IN THE MIDDLE OF PLATE ON ONE SIDE OR THE OTHER BURN A HALF MOON JUST A 1/2 INCH BIGGER THAN THE WELDED AREA. TACH IT TO WHERE YOU ARE GOING TO WELD, THAT SHOULD KEEP IT FROM BENDING

Jul 05, 2010
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Convex Fitting
by: Anonymous

I read a lot of good sugggestions but not much on the fitting. I often exaggerate the fit. I have used a 1/4" to 3/8" round stock in the pass to create a small convex look near the weld seem. Rolling the stock inboard or outboard, depending on the thickness and length of the base metals. This effects the amount of weight on the ends, so as the weld shinks the weight helps the two planes become one. Not forgetting to walk short staggerd beads. I use a rosebud and clamps as needed and not as a matter of course. A good straight-edge like a length of angle with a small piece of stock tacked on at each end lifts it over the weld so measurments can be made quickly and easily. Your weldment will shink and warp regaurdless of what you do. Stop, look, and listen. As it speeks answer.

May 22, 2010
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Reply
by: Jim

As I said before, I can't even attempt to offer advice for correction. The original post does not give enough information to even guess. To make an attempt I would need to know: 1. Base Metal type
2. Filler Metal type
3. Joint Type
4. Dimensions of Base Metal
5. Joining process (MIG, Stick)

Just to name a few.
And by the way, when doing heavy plate welding it is impossible to stop all weldment distortion. You can control it to a point. And when using strongbacks there is the concern of excessively restraining the joint against transverse movement as the weld shrinks, and thus increasing the possibility of weld cracking. It would also help to understand compressive stresses and tinsile stresses resulting from the welding process. If anyone has any questions they can ask.

May 22, 2010
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revision
by: Anonymous

you can clamp the plate on all four corners, or near the corners. You could tack backing bars perpendicular to the backside of the plate, use the backstep welding method while skipping around making small welds on different joints. Use a heat sink on the bottom of the plate, like a thick piece of copper, or brass. I left the comment about the plasma grinder, as a joke of course, but I hope any of these tips help....depending on how many you have to make you could always make a jig with quick clamps as a part of it.
best of luck
matt

May 22, 2010
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great advice jim
by: Anonymous

Jim your a great critic, but if your that good how about give your advice.

May 20, 2010
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helpful tips and tricks
by: Anonymous

as a welder of many years and completing many jobs, I have found if you utilize a plasma grinder and or a plate stretcher, it will negate this problem.
sincerely,
matt

May 20, 2010
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Inexperience
by: Anonymous

My best guess is that your people were doing a dual shield weld on that plate. 2" thick plate, or anything that thick has a vary narrow weld zone. I have to assume that it could not have been too leangthy or it would not have crowned on you. Pre-heat is a good thing but if you pre heat to 300F (150c) you may not be able to get close enough to weld it in the first place. Pre heat is good for cast-iron. but not so hot you can not work with it. The guy who said to v grove both side of the plate is the closest to the mark. Any thing that think need the double v groove weld so you can have the penitration you need. Make single passes on both sides and let cool. Heaving welding at one time will effect the grain, heck any heat effects the grain and changes the metal structure. I would sugguest that you get a book on metallurgy and look at the metallurgy of welding. Clamps are a big help and depending on what you need the metal to be after wards you might want to consider on your cooling technique. Adding water can help if you dont mind it becoming brittle and it wont take too much of a beating afterwards. Slow cooling is what i go for in most of my welds to allow the grain structure to get as close to base metal structure as possible. However it is never possible to get it back all the way no matter what you do because all heat will change grain structer every time. In your case, clamp it down or weld it down and let it cool completly before making another pass. Slow and steady wins the race and saves you money.

May 19, 2010
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v groove/ pre heat
by: Anonymous

Its hard to answer if you havent seen it. BUT, If your BUTT welding the plate, V-Groove both sides of both plates,per heat and weld one side then weld the other side back and forth.

May 19, 2010
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bending plate
by: peter james

yes the problem is over heating what you need to do is, weld some angle iron from corner to corner and then cut them of after it will help it to stop bending from the heat.you could also try welding about 1 inch at a time start top then to the bottom and keep doing this until you reach the middle.but give it time to cool of before you finnish i use a wet cloth.

May 19, 2010
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weilding tip
by: paul cashell

if you get a length of heavy gauge steel and g clamp to your work piece with as many clampa as needed and alternate your weilding from left to right. this allows each side to cool slightly and prevent heavy warping. its good a bottle of cold water there beside you to pour on after every 100ml and wipe dry before you commence wielding. this has worked for me. hope this is a help to you.

May 18, 2010
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You Have Got To Be Kidding Me
by: Jim

Is there anybody in here that is not guessing and actually knows what they are talking about. First of all, the first post did not give nearly enough info to even attemp to guess at a solution to the problem. Second, even the guesses were clear out in left field and were a clear indication that nobody has a clue as to what they are talking about. Are there any REAL fitters or fabricators in this forum? Sounds like a bunch of inexperienced weldors that don't know the first thing about weld theory or what acually happens during the welding process.

Apr 11, 2010
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old school
by: Anonymous

ya you need to strong back it and back steping will help alot thats wwhere you stop on your starts

Apr 11, 2010
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Distortion
by: Anonymous

Without seeing the workpiece certain assumptions have to be made but in general any welding in steel will cause distortion the trick is to even out the distortion by preping the plate (in the case of a but weld) from both sides and alternating between in multipass welds. To pull back the distortion try veeing out the opposite side and rewelding. next time try arresting the contraction with clamps.

Mar 09, 2010
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kinda like stiching
by: ricky robot

i dont know how long yor welds are,it sounds like you are running some long welds. if so trystaggering your welds.2" is also borderline preheat.

Jan 28, 2010
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Pre-Heat
by: Brad Hazlett

Sorry, don't forget to preheat and post heat.

Jan 28, 2010
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Braces, clamps and heat
by: Brad Hazlett

You must use braces, clamps and or hydrolic presses to hold the steel in place. Im going to say that you had a single-v groove or single bevel. You must run your root pass first to much heat will cause the plate to warp but being 2"s thick it should'nt warp on your first pass, you must run your passes at a slow and controlled temperature. Under ASME and AWS codes it will specify the heat range so that warping and the charicteristics of the metal are not changed. You should not exceed 500 degrees for steel but can be fluctual but not recommended. Use a heat gun or heat tape. Take your time and make sure you have the right setup and everything should work out great. If its only a butt joint just make sure you have it secured in place and run half plate on one side and run full length on other side. Hope all works out.

Brad (Newkensington)

Jan 27, 2010
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Put strong backs
by: Anonymous

Put strong backs on the back of the weld and attache them with atleast one inch long thick weld..
Strong back is like a Small bridge kinda shapped piece of metal looking some like this :
\_/-\_/ where the too bottom ends are welded to either plate and the center gab leaves the space for it not to effect the weld itself
Hope this kinda makes sence...

Sep 23, 2009
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Do lots of small welds
by: Anonymous

Whoever told you that you welded too much at once was right. You haven't to do on continuous weld. Instead you do lots of small weld alternating from one side of the weld to the other so the metal can stay as cool as possible. Its the heat that warps the metal. Do two inch or once inch welds at a time.

ALAN

Aug 27, 2009
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My Idea
by: Jenna

I believe what you should have done was use giant clamps and jump from one side to the next. It might bow a bit but not much or not at all.

Aug 17, 2009
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the pot belly effect
by: E-nasty

if your weld is thicker than 1/4 round off the edges and have it as ovuler as you can with out ruining the size of the piece.

Jul 18, 2009
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mcwelder
by: brent mcnamara

use as little heat as possible [turn the welder down as low as you can and still achive a good weld] and dont weld hot on hot allow time to cool

Jun 30, 2009
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distortation control
by: Anonymous

welding distortion is caused by the heat involved in the welding, when welded the area first expands a little but contracts more upon cooling causing the plate to bend. Preheating the weld structure opposite the side being welded helps alternating beads and large rods to reduce the time heat is applied also help.Pluse welding with mig will cut the total induced heat time. Ridgid clamping of the stucture to be welded helps and a stress rellieve post heating will also help.istition control is a big issue on many weld applications and text books have been written on this. Check with The American welding society and you can probbaly download the recommended procerures. This is a bigfield.

May 07, 2009
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Bevel ?
by: Cory The Welder

I always heard anything over 1/4 thick should have a bevel. Preheat is important on something thick.

May 06, 2009
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trouble solution
by: Anonymous

yes, it happens when you weld a thick plate.
it has two solutions.
1. pre heat the plate at about 150C and then weld
2. use the altenate weldind technique, i.e, 1st apply a pass from one side of the plate and then invert it and apply the next pass from the other side. repeat the same technique,you will get out of troble

May 04, 2009
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common problem
by: Anonymous

This is a common problem in all metal.
One area can heat up and expand before another area resulting in warpge. To see this on a smaller scale take a small flat piece of sheetmetal and heat the middle with a torch. WHat you should get is a cuped piece of steel since the middle will want to expand. You can reduce this by welding in one area going to another and skiping around to avoid large amounts of heat buildup in one area.

May 04, 2009
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Yes, it is
by: Anonymous

It is true.

The forces involved in metal dilatation or contraction by temperature they are ENORMOUS. A little welding point cede, but a large cordon maybe not.

I experienced the same effect with a small L bar.

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