# Welding cast iron



## talob (Sep 16, 2009)

I picked up an old cast iron cooking pot the other day its 23" across 16" deep and about 1/4" thick, it has a crack down one side of it, it just seems like I'd heard that you should heat up cast iron befor you weld it, so my thought is to grind a shallow groove along the crack heat it up and use cast iron welding rod sound about right?


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## zimmy (Aug 17, 2012)

*Weld cast iron*

Dig a hole in the ground and start a charcoal fire, put cast iron on coals and weld with stainless or cast iron rod, after welding, cover over with dirt until next day, good as new.


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## airdrop (Jan 6, 2012)

Cast is hard to weld because it recracks so easy but yes heating it will allow it to cool slowly altogether . Brazing rod is used , I've seen Nichol rod used to weld it back together with electric welder. Start at the ends of crack then in the middle doing small welds to fill up the crack so you don't heat one area to hot this, method is used if you don't heat the item up. Your pot is a nice piece to practice on 
At the welding shop I've watched him heat with big propane torch ,weld then cover with fiberglass bats so it cools slowly.


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## Tirediron (Jul 12, 2010)

DO NOT use brazing rod. Zimmy's approach is about the best, I would drill small holes at the ends of the crack, to stop the lattice fracture, grind out a bit of a grove , heat the iron up good and hot as described. if you have an oxy acetylene torch use an oxygen rich flame to burn any contaminants out of the grove before welding. (gas welding cast is very successful, but finding filler rod would be pretty hard these days) weld it from the ends to the middle, using hi nickel cast rod (stainless has too much chrome for a dynamic loaded repair like this) on both sides if possible, return it to the heat source and let it cool slowly.


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## talob (Sep 16, 2009)

Thanks for the replys guys, Zimmy were talking a big hole here! Drilling a hole at the end of the crack (if I can find the very end) had crossed my mind, figured grinding one side weld it then grinding the other side and weld so as not to get it to thin at the crack, didn't know about welding from ends to middle, this has a lot of surface area to keep warm without digging that big hole.


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## LincTex (Apr 1, 2011)

Tirediron said:


> using hi nickel cast rod (stainless has too much chrome for a dynamic loaded repair like this)


Correct - Nickel is a much more malleable metal, kind of like how copper acts - and it will "move" a little bit as needed to go with the flow when cast iron moves. Stainless wont do that.

Lots of heat will be your friend - I ALWAYS weld cast when it is dull cherry red. Slow cooling down is absolute necessary.


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## nightwing (Jul 26, 2014)

LincTex said:


> Correct - Nickel is a much more malleable metal, kind of like how copper acts - and it will "move" a little bit as needed to go with the flow when cast iron moves. Stainless wont do that.
> 
> Lots of heat will be your friend - I ALWAYS weld cast when it is dull cherry red. Slow cooling down is absolute necessary.


ah hell use that stuff on TV spray seal it works on a boat with a screen door in it :2thumb:


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## readytogo (Apr 6, 2013)

talob said:


> I picked up an old cast iron cooking pot the other day its 23" across 16" deep and about 1/4" thick, it has a crack down one side of it, it just seems like I'd heard that you should heat up cast iron befor you weld it, so my thought is to grind a shallow groove along the crack heat it up and use cast iron welding rod sound about right?


http://www.aluminumrepair.com/more_info.asp


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## readytogo (Apr 6, 2013)

make sure area is very clean,free off oil and grease,have charcoal ready like zimmy said and pour charcoal into pot and around to keep hot and allow to cool over a long period,also this are new rods especially made for difficult jobs.
http://www.aluminumrepair.com/


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## Tirediron (Jul 12, 2010)

I would be pretty shy about fixing anything important with HTS-2000, the way wrong use of trade terms is scary, if it does work, it is a soldering process, and if it isn't brass it definitely is not brazing.


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## talob (Sep 16, 2009)

readytogo said:


> make sure area is very clean,free off oil and grease,have charcoal ready like zimmy said and pour charcoal into pot and around to keep hot and allow to cool over a long period,also this are new rods especially made for difficult jobs.
> http://www.aluminumrepair.com/


Thanks, I bookmarked the website, I may get some of this stuff to play around with I can see uses for it, but for this job I'll probably use cast iron rod and like you and zimmy said build a good fire in the fire ring with a good bed of coals and just lay the cauldron in the coals.


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## Magus (Dec 1, 2008)

zimmy said:


> Dig a hole in the ground and start a charcoal fire, put cast iron on coals and weld with stainless or cast iron rod, after welding, cover over with dirt until next day, good as new.


Yup.
Alternately you can heat it with a rosebud, fill it with DRY sand, flip it then weld it while its still hot, then place over low heat for 30 minutes and gradually reduce the heat over that time. either method will ensure it cools evenly and the iron doesn't crystallize or fracture.


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## goodoleboy64 (Feb 24, 2011)

What has always worked for me is nickel rod then ping the weld while it cools. Cast has a grain and tapping (pinging) helps the grain re-establish. Preheating is always good so is drilling the hole.


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## talob (Sep 16, 2009)

Just for grins I'm gonna take it to a small local welding shop and get a price and see how he would fix it, I priced cast iron welding rod at TSC the other day and went into sticker shock They want 32$ for ten sticks of rod I'd probably use half of it and never use the rest, anyway I'm looking at options.


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## LincTex (Apr 1, 2011)

talob said:


> I priced cast iron welding rod at TSC the other day and went into sticker shock  They want 32$ for ten sticks of rod


Wow, really? I have never paid that much for it.


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## Magus (Dec 1, 2008)

How good are you at silver brazing?


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## Tirediron (Jul 12, 2010)

silver soldering, brazing requires brass, (I only pointed this out cause you know about metal processes, and people might decide that the nomenclature is correct and we know where that will go, ) I have never tried to fix a crack in cast with silver, I guess it should work if the lattice is coarse enough. 

Forney welding products often has cast electrodes in very small packages, like 2 or 3 1/8" rods


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## talob (Sep 16, 2009)

Magus said:


> How good are you at silver brazing?


I'm pretty fair at brazing, Tirediron I'll Bing Fourney products and see what they have, still havent gotten it to the welder yet to see how he would do it.


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## Magus (Dec 1, 2008)

Make sure it's real silver and not the lead based crap, you don't want that in your fried eggs!


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## Viper (Oct 28, 2014)

Welding Cast Iron is real tough. The stuff is already brittle and welding worsens the condition.

Get the area to be welded to near red hot if possible. Use a gas torch for the purpose. Thin pans may reach the required temperature even with a butane torch. Once red hot, weld as normal but maybe moving a bit slower than usual, with a cast iron welding rod. Nothing else holds on better. Deposit extra material if required, which can always be removed by some grinding....


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## talob (Sep 16, 2009)

Thanks, that's how I'll do it if I do it myself I'll also grind a shallow grove on one side to fill with weld and ping it as I go, haven't done anything with it as my whole world has been turned upside down so this project is on a back burner for a while.


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## LincTex (Apr 1, 2011)

When I did my Cummins diesel swap, I had to modify the exhaust manifold and also build a spacer so the turbo inlet wouldn't hit the oil filter. I preheated the parts with a rosebud, used a "black" welding rod, and cooled off slowly with the rosebud. Almost a decade and tons of miles later = no issues.


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## gypsy (Nov 17, 2014)

Just be sure to bring it back with heat after welding


Sent from my iPhone using Survival Forum


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## Jewel (Sep 6, 2014)

Is it still food safe after welding? I have a small cauldron I want to have repaired but it has the bottom burnt out of it. I'll have it fixed regardless but just use it for soap and candle making if it's not food safe. I have a friend who's a welder by trade and he didn't think it would be.


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## Tirediron (Jul 12, 2010)

If it is welded with hi nickel rod or cast rod it should be fine for food, solder often contains lead and would be a lot less safe. brazing would depend on the filler composition.


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## Magus (Dec 1, 2008)

Mostly the filler is the same as Crest toothpaste. I'm allergic to fluoride so not for me anyway.


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## LincTex (Apr 1, 2011)

Jewel said:


> Is it still food safe after welding? I have a small cauldron I want to have repaired but it has the bottom burnt out of it. I'll have it fixed regardless but just use it for soap and candle making if it's not food safe. I have a friend who's a welder by trade and he didn't think it would be.


If it's so bad it has burned through... welding with a nickel rod will only finds all of the other weak spots!

I would sandblast it, then braze it over the "burned out" area with a brass rod and a rosebud torch.


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## Jewel (Sep 6, 2014)

LincTex said:


> If it's so bad it has burned through... welding with a nickel rod will only finds all of the other weak spots!
> 
> I would sandblast it, then braze it over the "burned out" area with a brass rod and a rosebud torch.


Thank you. Would most certified welders understand that? Like typical mig and tig?


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## LincTex (Apr 1, 2011)

Jewel said:


> Thank you. Would most certified welders understand that? Like typical mig and tig?


MIG won't work on cast iron for a long term repair, it'll crack again right next to the weld.
I have actually never tried to TIG cast iron. Hmmm...

A "rosebud" heats a large area.


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## crabapple (Jan 1, 2012)

There are rods made just for welding cast iron, no guess work at all.
Go to a welding supply store, not big box/farm store.
As for heating, it depends on what kind of cast iron it is, some need heat, other do not.
Malleable cast iron should not be heated above 1382F or 750C or it will revert back to white cast iron.
60 degree v grind & a hole drilled in the end is a good start in preparing cast iron for welding.
Never did zimmy trick, but it sounds like a treatment that has been around for ages.
That pot sounds like a good find & would cost if you could even find it knew.


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## Jewel (Sep 6, 2014)

I meant, would a certified mig/tig welder be able to do it or is it a specialty. sometimes things make sense in my head ...

thanks for all the information! I'll ask around and see


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## crabapple (Jan 1, 2012)

Jewel said:


> I meant, would a certified mig/tig welder be able to do it or is it a specialty. sometimes things make sense in my head ...
> 
> thanks for all the information! I'll ask around and see


IMHO,most certified welders can mig/tig & stick weld.
The classes I took also had acetylene torch welding which has been replaced by mig in most shop & acetylene for cutting & heating metals.


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## Tirediron (Jul 12, 2010)

Most welding courses are aimed at mainstream markets, here they teach with pipeline pressure welding in mind, when I was in SAIT 25 + years ago you still got taught how to gas weld (oxy acetylene) and just touched on cast welding, I took some extra stuff on cast and other repair methods due to my plans for doing repair instead of pipelining.

current welder I would imagine are even more mainstream.


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## simplepeasant (Oct 26, 2015)

Just put it in the oven and heat it up to 350 or 400 degrees. Grind your V. Make sure it's clean. I just use a wire wheel on my grinder for that. If you're using an arc welder use nickel (although it's spendy)if you have a wire welder just turn it up good and hot and burn it in. I was a production welder for John Deere before opening my own shop. All cast was welded with wire. We heated it up with the root pass and finished it with the second or third if the print called for a big weld. I fix a lot of cast for farmers around here.


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## oldasrocks (Jun 30, 2012)

simplepeasant said:


> Just put it in the oven and heat it up to 350 or 400 degrees. Grind your V. Make sure it's clean. I just use a wire wheel on my grinder for that. If you're using an arc welder use nickel (although it's spendy)if you have a wire welder just turn it up good and hot and burn it in. I was a production welder for John Deere before opening my own shop. All cast was welded with wire. We heated it up with the root pass and finished it with the second or third if the print called for a big weld. I fix a lot of cast for farmers around here.


I do the same but use stainless steel rod for the weld.


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## zombieresponder (Aug 20, 2012)

I'm not a welder by trade, but end up doing all of it where I work. I only use nickel rod on cast *iron*, and generally the "99%" nickel rod since it almost always has to be machinable after I'm done with it. Preheat-weld-postheat-slow cool.

Cast _steel_ is not the same as cast iron and in my experience, can generally be welded the same as regular mild steel.


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## Magus (Dec 1, 2008)

Pre heat is a good idea on ANY cast item.


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## crabapple (Jan 1, 2012)

Some cast iron should only be preheated to above room temperature, much higher & it will change the cast iron.


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## Magus (Dec 1, 2008)

Or crack it. forgot about that dutch oven and frying pan I tried to fix ages ago. did not end well.


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