Welding cast iron

[hh76]

I've got an old franklin stove that I got for free. Was going to clean it up and set it on the patio as an outdoor fireplace.

Just noticed a small crack in the side. Not really a big deal, and could live with it, but I thought I'd be a good excuse to play with my welder.

I've been reading up, and it seems like it can work, but there is a good chance that there would be some cracking.

The big question is, how much worse would the piece be if I failed? Would it just be some small cracks in the area around the weld, or could it potentially ruin the whole part? It's a side panel approximately 20x25" about 1/4" thick.

I'd be using my tig welder, and am still reading up on which filler.

 

[dogdog]

was told to use those "ni 99 tig rod" or ER309L (maybe ER309H also, recently got a batch was told H is high carbon content....)... when I asked a similar question for cast exhaust manifolds.
as far as cracks, you are suppose to drill relief hole at the ends of the cracks and v out the crack for the filling. Pre-heat and post heat so the whole piece heats and cools uniformly .... there are few youtube videos about these......

 

[j p smith]

Look at EZ Weld Tig Rod. There is a video of a piece that was welded, something for Jay Leno I think

 

[racingtadpole]

I am at this point wondering if you couldn't just fire it up for your pre/post heat?

 

[danscobra6]

I used ER309L as mentioned above to repair my belt sander. Preheated to 250 and after welding kept it heated for a slow cool down. No sign of cracking after almost a year.
3/32 Lanthanated
1/16 filler
Around 150 amps with pedal
14 CFH 100% argon

 

[jumbojak]

I am at this point wondering if you couldn't just fire it up for your pre/post heat?

That's what I would do. The big problem with welding cast is the thermal shock.

Another thing to consider is the final appearance. If you use an E99 or similar rod the weld is going to stick out like a sore thumb once you're finished. Might be better to leave it alone if the crack is conspicuous and you think you can live with it.

 

[dogdog]

Look at EZ Weld Tig Rod. There is a video of a piece that was welded, something for Jay Leno I think

I think that was the Mr. tig video on cast iron repair, some viewer point out about a further cracking of the piece during his welding repair without pre-heat and post heat... he didn't respond back on that video...

 

[rsanter]

Can you brass brase it from the back side so it doesn't really show?

Bob

 

[visedog]

Brazing will be my advice too.

 

[SlappyWhite]

I am at this point wondering if you couldn't just fire it up for your pre/post heat?

That's what I would do. The big problem with welding cast is the thermal shock.

Another thing to consider is the final appearance. If you use an E99 or similar rod the weld is going to stick out like a sore thumb once you're finished. Might be better to leave it alone if the crack is conspicuous and you think you can live with it.

Agreed!

As for the weld being visible, as long as it is a good looking weld I say it is just a badge of honour.

 

[hh76]

Weld won't be visible, I'm going to stack some brick around it.

Good point on using the stove to preheat itself.

If the thermal shock does cause more cracking, how bad can it be? Would it be worse than the original crack, or just some minor hairlines? The existing crack is about 4" long.

 

[tc-cad]

When I worked at a Large Bathtub MFG in WI they always heated up the cast iron with a torch until entire area was cherry red then they welded the cracks.

 

[G-ManBart]

I'm far from the most experienced welder, but wouldn't firing it up get a lot of soot and junk on the parts you want to be clean? Inconel rod works nicely on cast iron and ductile iron...it's nickel based.

 

[dogdog]

maybe those large Propane weed burning torch ? or prep everything, heat , grinder / wire brush just before welding

 

[jumbojak]

Weld won't be visible, I'm going to stack some brick around it.

Good point on using the stove to preheat itself.

If the thermal shock does cause more cracking, how bad can it be? Would it be worse than the original crack, or just some minor hairlines? The existing crack is about 4" long.

The thing I've learned about cast is that you can never be completely sure how it's going to react if you aren't very careful. I've seen someone successfully build up tack welds using 7018 without cracking. I've also seen the weld come apart and enlarge the original crack before when too much was done too quickly. Same guy, by the way.

I'd just make sure the temp had plenty of time to come down, whether you light set stove or use a torch and insulation like sand. One other thing to consider, will your tig torch be able to shield the weld if the stove is outside? I'm no tigger but my limited experience with might suggests that any wind or breeze could cause problems for you.

 

[sberry]

Some cast welds good, some doesn't. Its fussy and I am not patient. A metallurgist would have the right heat but basically warm it up some so it cools slower and not every piece gets warmed to cherry but some with slow paced careful cool welding.

 

[NASTYZEN]

I've welded many stove parts in the 34 years since I began my welding career.
In my personal opinion, welding a wood stove that will be in a space where people live is taking a big chance with peoples lives. I no longer fix or weld wood stoves. Cast or steel plate.
I've not had a failure that I know of. But I just don't feel comfortable with it.
The best welder I've had work for me, brought in his slow combustion wood stove to fix it once. His house burned down that winter. He and his family barely made it out in time. Lost absolutely everything including his two vehicles parked in the driveway...
Can it be done safely? Sure by all means. Still a gamble.
When my stove breaks, it's going to the wreckers. It's not worth the money.
Best of luck friend.

 

[joe49]

High temp flux and brazing rods made of cast iron. Cast iron piston rings can also be used. Same pre and post heat.

 

[sberry]

Repair is what we do, there is no problem fixing wood stoves. Fundamentally changing designs on them or some controls is a problem.

 

[skrap metal]

ive had good luck with nickel filler

 

[brownbagg]

preheat, nickel rod, peen

 

[toplessHO]

preheat, nickel rod, peen

and I ll add post heat with a rosebud or propane torch
then bury in clean dry sand
until this no one mentioned peening which stress relieves

 

[bon3s]

Royal 11-10 Tig rod is what I have used in the past.

Grind out for a good landing area - carbide burrs work best.
Preheat, weld a small amount, peen, weld a little more, peen, repeat till finished.

At the end peen and wrap in Kaowool.

This is what i choose to use and it seems to work rather well for the applications ived used it for (cast drain covers, and other small odd jobs, personally ive never done a stove and it would be down to where and how bad the dmg was if i would bother with it).

 

[hh76]

Tomorrows the night, assuming I can get to the welding shop and pick up the right rod. Not exactly sure which I'll use, It'll depend on what they have.

I'll put it on the propane grill for a preheat, then carry to the garage for the weld. I'll bring it back out to the grill for a cool down.

What kind of settings should I begin with? Mostly 3/16" thick with some thicker spots where the crack crosses ridges.

 

[hh76]

If you consider that I learned a few things, I'm calling it a success.

I did have a small crack form at the end, but the original is solid again.

 

[PugetDude]

If you consider that I learned a few things, I'm calling it a success.

I did have a small crack form at the end, but the original is solid again.

Stop drill the end of the crack, then fill with weld.
It's the only way to keep the crack from continuing to run.
Post pics of the repair!

 

[rsanter]

Tomorrows the night, assuming I can get to the welding shop and pick up the right rod. Not exactly sure which I'll use, It'll depend on what they have.

I'll put it on the propane grill for a preheat, then carry to the garage for the weld. I'll bring it back out to the grill for a cool down.

What kind of settings should I begin with? Mostly 3/16" thick with some thicker spots where the crack crosses ridges.

Move the grill to the welding area.
I have used the BBQ for preheating on several things I have welded.
I heat the item up, open the BBQ and do the welding right there. Then close the BBQ and cook it a little longer. Then I turn the BBQ off and just let it sit insode to cool slowly

Bob