I have a project to weld a crack in a seasoned cast iron pot used to cook cracklin in. Any advice will be appreciated. What type of filler metal? How much pre heat and post heat? I prefer to tig weld the repair but open for any suggestions.
- castweldsolutions
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Here are some parameters I would follow:
Process: GTAW "tig"
Polarity: AC High Frequency
Filler metal: Aluminum Bronze
Gas Shielding: 100% Argon
Amperage: 100 amps
I would first clean the pot very very thoroughly. I use Blue Gold cleaner on cast metals and it works really well. Soap and hot water works. Degreasers are great, but make sure you use a degreaser that doesn't have chlorines in it (just read the warning labels).
Drill holes at the end of each crack to prevent it from spreading once you apply heat or start welding.
I would preheat the pot to 500F degrees before welding. 500 is best, but any heat is better than no heat, just preheat it as best as you can. Couple of ways you can go about doing this. An oven would be best. Most castings are preheated with an oxy fuel torch. Just make sure you preheat the whole piece and not just the crack.
After all that, you can go ahead and weld it.
Technically, when using aluminum bronze and AC polarity, you'll actually be tig brazing. The cast shouldn't melt, just the filler metal.
After you weld it, you must slow the cooling rate down. This is the most important part of the whole job. If you have an oven then stick it back in there and just turn the temp down a little every thirty minutes or hour or so until it is room temp. If you have a torch then you need to fan it with the torch and cool it slowly that way. Some people just use sand. Submerge the part in sand and that will insulate it and slow the cooling rate down. This prevents the piece from cracking.
Here are a couple of videos that helped me out:
https://youtu.be/FUUj5DyQGik
https://youtu.be/jJg5RcljNao
Process: GTAW "tig"
Polarity: AC High Frequency
Filler metal: Aluminum Bronze
Gas Shielding: 100% Argon
Amperage: 100 amps
I would first clean the pot very very thoroughly. I use Blue Gold cleaner on cast metals and it works really well. Soap and hot water works. Degreasers are great, but make sure you use a degreaser that doesn't have chlorines in it (just read the warning labels).
Drill holes at the end of each crack to prevent it from spreading once you apply heat or start welding.
I would preheat the pot to 500F degrees before welding. 500 is best, but any heat is better than no heat, just preheat it as best as you can. Couple of ways you can go about doing this. An oven would be best. Most castings are preheated with an oxy fuel torch. Just make sure you preheat the whole piece and not just the crack.
After all that, you can go ahead and weld it.
Technically, when using aluminum bronze and AC polarity, you'll actually be tig brazing. The cast shouldn't melt, just the filler metal.
After you weld it, you must slow the cooling rate down. This is the most important part of the whole job. If you have an oven then stick it back in there and just turn the temp down a little every thirty minutes or hour or so until it is room temp. If you have a torch then you need to fan it with the torch and cool it slowly that way. Some people just use sand. Submerge the part in sand and that will insulate it and slow the cooling rate down. This prevents the piece from cracking.
Here are a couple of videos that helped me out:
https://youtu.be/FUUj5DyQGik
https://youtu.be/jJg5RcljNao
Tyler
- Otto Nobedder
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If you have cats, there's potential "entertainment value", too!Boomer63 wrote:To slow the cooling rate, bury the hot pot in a pile of sand; preferably a box you have fabricated filled with sand. It will cool slowly and evenly over a period of a COUPLE OF DAYS!!
Gary
Steve S
Oh you like the cat stories?
When I was young an old timer told me the story of when he was young he came home from school one day and his mother told him to go see the old lady next door who wanted to get rid of her old tom cat. the old lady asked him to put the tom into a hessian bag and chuck im in the river. So the tom knew he was for it and fought tooth and nail and the lad was half shredded getting im into the bag. Undeterred, he tied the bag to his bike handle bars and pedaled off to the bridge. halfway there the cat escaped the bag and passed through his front forks causing him to cartwheel down the road. Dazed, bruised and bleeding he gets up and fights the tom again to get im back into the bag getting tore up some more in the process. Finally he gets to the bridge, ties a brick to the bag and chucks im into the drink saying go to hell you bastard. So he pedals his bike home with now a bent front wheel and when he gets home the cat is there waiting for him.
When I was young an old timer told me the story of when he was young he came home from school one day and his mother told him to go see the old lady next door who wanted to get rid of her old tom cat. the old lady asked him to put the tom into a hessian bag and chuck im in the river. So the tom knew he was for it and fought tooth and nail and the lad was half shredded getting im into the bag. Undeterred, he tied the bag to his bike handle bars and pedaled off to the bridge. halfway there the cat escaped the bag and passed through his front forks causing him to cartwheel down the road. Dazed, bruised and bleeding he gets up and fights the tom again to get im back into the bag getting tore up some more in the process. Finally he gets to the bridge, ties a brick to the bag and chucks im into the drink saying go to hell you bastard. So he pedals his bike home with now a bent front wheel and when he gets home the cat is there waiting for him.
Flat out like a lizard drinkin'
- Otto Nobedder
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exnailpounder
- exnailpounder
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Cat stories...I was repairing a piece at a shop I worked at and they had a shop cat who shit all over the benches and everywhere else so I ended up with catshit on my shirt...the cat jumped up on the bench and I grabbed a can of starting fluid and sprayed his bunghole with it....he took off into the bosses office ....the starting fluid gave him violent diarhea...he shit ALL over the carpet, couch and boxes of paperwork. I saw what he did, shut the door and left for the weekend. Never seen that cat again. Either the boss killedhim or he shit himself to death...true story 
Ifyoucantellmewhatthissaysiwillbuyyouabeer.
- Otto Nobedder
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Li'l Billy asks the priest about the power of Holy water. The priest explains, "Why, I can rub this Holy water on a pregnant woman's stomach, and she'll pass a baby girl!"
Billy says, "That's nothing. I can rub turpentine on a cat's ass, and he'll pass a motorcycle!"
Steve S
Billy says, "That's nothing. I can rub turpentine on a cat's ass, and he'll pass a motorcycle!"
Steve S
Thanks for all the advice. Even the cat stories. And I do have a shop cat.Bradco wrote:I have a project to weld a crack in a seasoned cast iron pot used to cook cracklin in. Any advice will be appreciated. What type of filler metal? How much pre heat and post heat? I prefer to tig weld the repair but open for any suggestions.
- Otto Nobedder
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Bradco,
I apologize for the "cat story" Hi-jack of your thread...
This forum will take strange turns, now and then, when boredom is up and beer is out.
I'm glad you got useful information, and I hope you didn't let the shop cat read this...
Steve S
I apologize for the "cat story" Hi-jack of your thread...
This forum will take strange turns, now and then, when boredom is up and beer is out.
I'm glad you got useful information, and I hope you didn't let the shop cat read this...
Steve S