Any way to soften a mig weld?

Is there any way to soften a mig weld to be able to hammer and dolly a panel without cracking the welds? I wish I was able to get my hands on a tig but it's just not going to happen anytime soon. Is it possible to anneal it with a torch with a small tip?
Thanks Nocero

 

I have wondered if acetylene/oxygen heat would anneal the weld too.
Try it and tell us how it works.

 

From what I have read and what I was taught that you do not hammer on mig welds. They are just to hard. Oxy/acetylene welds are softer and can be hammered. Todd

 

How do you heat the weld and not the panel? Seems like you would warp the piece and harden it at the same time.My last 2 cents

 

MIG welds seem to be harder because they apply an instant high heat to a smaller area and the sheet metal cools rapidly leaving them in a state of hardness greater than a torch weld that heats longer and spreads out more, so cools somewhat slower.

Sometimes, you are dealing with a greater metal m*** when working with a MIG weld so a gas weld will seem easier to handle too.

Yes, torch reheating and cooling to anneal works fine. (redo often as you go to control work hardening of the area and cracking.) I use a small gas welding tip directly on the weld area and just go barely a dull red in a shadowed work area.

 

If your going to go back over the weld with a torch, then why don't you just 'hammer weld' it to begin with. You can never hammer on a mig weld without cracking it. Mig is just to hard because of the physical make up of the wire and the electrical process. There used to be a wire available in some areas called 'easy grind' but I haven't been able to find any in some time now. You still could not hammer it but it was a little softer for dressing. Check with Ron Covell, he's the guru of welding wires, treatment, processes, etc. When I metal finish, I hammer weld, period.
Carl

 

I prefer gas welding, but Randy Ferguson uses a mig welder and does very fine work which proves that it is possible:

http://fergusoncoachbuilding.blogspot.com/2007/04/mig-welding-thin-sheetmetal.html

John www.ghiaspecialties.com

 

Easy Grind is made by ESAB, in a couple of different varieties. As mentioned, it's designed to be easier to grind down than conventional wire...some like it, some don't, but it might be worth a try for you. http://products.esabna.com/EN/home/..._id.id4367f2a958f8c3.05458256/category_id.504

 

Depends on the wire you are using............There are wires that grind a lot easier than others, (I forgot the name). A good welding supply should be able to help.

 

I have learned to be extremely careful about hammering a mig weld as I have experienced cracks later on that cost me a lot of time and rework. Remember, most of these cracks are almost invisible to the naked eye. I have had cracks show up too many times to chance hammering on a mig weld. If I ever do need to hammer the weld, I then run a torch along the weld and if it has cracked it will become visible as it heats up. I would much rather hammer weld anyway so I can really work the metal as I go. I never try to metal finish a mig weld. It's just too brittle to bang around on. Mig is good for tacking things together before hammer welding.
Carl

 

Sorry, but this is not true! Its not the wire, its the melting, heating, cooling process. Most standard MIG wire is ER70S-6. Guess what most tig rod is? ER70S-6! And what do most people gas weld with? ER70S-6!

TIG and Gas welding slowly heat the panel, and then it takes a lot longer to cool, which is an annealing process. MIG heats the metal up very quickly, and cools much faster, which is a hardening process.

To prove this, if you do use a torch to re-melt, or just bring a MIG weld to cherry red and allow it to cool, it will become soft, and easy to hammer and grind. Still the same wire, but a slow heating and cooling cycle anneals the weld bead and HAZ.

Now there are some wires (like ESAB Easy Grind) that do help make a softer weld, by changing the alloy of the wire, but its still never as soft of a weld as you get with the TIG or gas welding process.

 

.........because......you can't get soft iron wire for a mig. ESAB Easy GRind is NOT SOFT IRON wire, it is alloyed.

 

I used to work with a guy who swore you could metal finish MIG welds. He did a bunch of custom work on his car that way. Looked good, until he painted it and started to drive it. Cracks stared showing up most of the places he had worked the welds. They were there all along, just couldn't see em.
The next time he tried the torch annealing process on the mig welds. Warped some pretty nice panels because the welds were to thick compared to the metal.
Next ................. He bought a TIG

 

Hey,

When hammering on a mig weld bead, be sure to gring the "proud" area of the bead, near flush with the surrounding metal. Don't overgrind the bead to the point that it turns blue, with firescale!

Why not pick up a oxygen/acetylene set up, try garage sales,swap meets,
Craig's list, pawn shops or retail welding supply houses. A set of small regulators, hose and a size O,OO,& a #1 tip should cover it. Spend thirty minutes a day in pratice, running beads on thin sheet stock. Try **** welds, Lap & Fusion welds in all positions.

Mig welds are great for production collision "metalwork", quick tacks and butchery-type pound and mud type "metalwork", but as your skills progress you'll want to move on to the gas or tig process and avoid all the silly grinding and pounding.

Good luck,

S****ey Devils C.C.
"It's time for another Tea Party ! "

 

You agreed with this post:

Quote:
Originally Posted by whamoman
Mig is just to hard because of the physical make up of the wire
You said:
Correct, it's harder because of the wire. Not necessarily TOO hard.


My point is that that is false. MIG is not hard because of the makeup of the wire! Its the same exact metal as is used in TIG/Gas welding rod 90% of the time!

MIG beads are hard because of the heating/cooling process being too fast.

90% of TIG MIG and Gas welding all use the same ER70S-6 filler metal!


Why would you want to use junk soft iron wire? That stuff is used for bailing because its cheap (i.e. low quality metal). It wont have the same properties as the parent metal. If your using un-wound wire anyway, it has to be Gas or TIG, why not use standard ER70S-6 filler rod, and your weld will be as soft as the parent metal because of the heating and cooling cycle.

 

So explain how a COLD TIG or Gas weld hammers and grinds MUCH easier than a COLD MIG weld, when both are welded with ER70S-6 filler wire.....

 

This is the biggest pile of **** I have ever heard. As Chad S stated most REAL welding wire either TIG or MIG is the same wire. Lots of guys will use mig wire right off a spool to TIG sheet metal with and get a nice soft weld. It is completely due to the process NOT the wire.

Of course if you use a **** soft metal to tig or O/A with you will get a softer bead than if you use real welding rod but you are just introducing **** metal into your project. Not something I would want to do and nothing to do with the different welding processes.

 

MIG wire is hard to grind. Use a sanding disk and it cuts like ****er.

 

My point was the COMBINATION of the wire alloy AND the application process causes the weld to be extremely hard and brittle. If you could use a spool gun (pull method) as with aluminum and there was a softer alloy that you could buy to use in that application I think you could have a softer, more mallable weld. I don't know if there's any such animal availble but I would think as many guys as there are out there using migs that it could be a pretty good market for Lincoln, Miller, etc.
The problem I see with torch welding or hammer welding is it is much more complex than using a mig. Both hands are very busy welding, hammering, dollying, quinching, placing the torch aside and picking it up again without ever taking your eyes of the metal takes a lot of practice and skill. I've been hammer welding for 40+ years and it still gets a little nerveracking in certain situations. I did a story for one of the mags back in the 70's about hammmerwelding a huge hole in the dash of a truck where someone had installed an 8 track or something crazy. So here is a torch stand, torch, hammer, dolly, welding shield, water bucket and rag, and a magazine photographer, all in a pickup cab! Now it's time to start hammerwelding, and don't forget all the wiring, gl***, gauges, etc. are still in place! Thats about the time I start thinking migs are pretty handy sometimes.

 

No matter what form of welding...the wire/rod melts. It's liquid as it forms the puddle.
Being hard or soft on the roll is meaningless to the finished weld.
Weld hardness/likelyhood of cracking is a result of the speed of cooling.
Thats why steering parts or whatever never get quenched but often get an extended cool down time to allow the metal to retain some softness as opposed to becoming brittle.

 

I would guess they don't do it because the only place it is really an issue is in restoration or hotrod building sheet metal work and given the process it will still result in a harder weld than a comprable tig or O/A weld. There would not be a big enough market to justify and at the end of the day you are still introducing a less desirable metal into the equation in order to make it soft. Most top end sheetmetal guys are already using tig or O/A and are happy with it.

 

I use the "20-gauge" MIG wire. It works pretty well. I don't remember who makes it, but it is a steel wire with a powdered iron core to get into spray territory with much less amperage and it's great for sheetmetal.

As Pimpin Paint said, grind the proud part of the weld bead down before doing anything - that applies to MIG, TIG or gas welding (unless you're working it hot).

Going over the bead does anneal the weld area...it also makes a larger HAZ and takes a bit of work to stretch back out. Someone said you can't anneal steel? Well, that is pure BULL! Admittedly, you probably aren't going to be able too cool it slow enough to get it dead-soft, but it will be softer than a MIG weld and it is quite possible to get it softer than its "original" state.

If you have a torch, gas weld it. I tend to just use the MIG to do the tacks - much easier to get everything lined up and hold it in place when all you have to do is pull the trigger - and then do the finish welding, about 1-inch at a time, with the torch. I use ER70S-2 for gas welding, it has a little less silicon and tends to make a slightly softer weld. I have a roll of ER70S-2 MIG wire that I use for gas welding really thin stuff, since I can't seem to find the rods in anything smaller than .045". The MIG wire I use is .030"

Sometimes I just get lazy and MIG it all together.

Tim D.

 

MIG welds on sheet metal have always looked like **** to me. Maybe because I can gas weld body work just like custom coach builders did in the 1930's. I can TIG aluminum bodywook too. MIG work is for Bondo slingers IMO.

 

so if you weld in a small patch with a mig and it doesnt pull enough to distort the area, you see no reason the try and hammer the weld to stretch it back out i dont think you will get cracks. i do agree that its not the best way to go and OA would be better.

 

I didn't mean to start a arguement here. My intention was to weld a couple pieces of s**** with the mig being careful not to warp it, then grind the weld nearly flush and go over it with the torch with a small tip to see if I could work the area.

If this does not work I guess maybe it's time to take a break from the coupe and practice gas welding. I was fairly decent at tig welding however I have not done it in a couple years now. Am I going to be able to pick up gas welding fairly easy compared to tig?

 

That came out wrong, what I should have said was take the time to learn to gas weld. If the car has bodywouk worth restoring to new condition MIG welding and a few pounds of Bondo aren't the way to do it IMO

 

Here is a very good site that explains the heat treating processes from an engineering and metalurgy perspective. You will see exactly why the welds are hard, why they crack, why the hammer welding process seems to be better. How to and or why you can treat the mig welded panels to be just as soft ( Annealed )

Also why some of the processes you may be using are actually self defeating. (hardening)
You will see why some of the processes you found to work well by accident or thru p***ed down knowledge works for what you are doing.

Seems that there is a great debate going on in alot of threads about this subject.

Every one is partialy correct.





There is a catch with this site: It is only free for about 10 mins.

Before opening it I would open some do***ent program that you have and capture the info via "print screens" and save them then go back and read it.

www.efunda.com/processes/heat_treat/softening/annealing

 

just watched this recently, thought it was appropriate for this discussion

http://www.jaylenosgarage.com/video/video_player.shtml?vid=236847