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  1. #1
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    Default welding cast iron

    Hi guys,
    I made a stupid mistake the other day and I am wondering if these is a relative easy eascape?

    I have zero experience welding cast iron.

    Would it be possible to tack this piece back in place?
    Was thinking of veeing out along the crack and making small welds with my Transmig 200.

    I have a feeling the only way to do it would be vee the crack, pre-heat the whole casting ( not possible in my case ), make small welds and slowly cool the item over a couple of days, to prevent cracking?

    Am I right to think I can't fix this?

    Steve


    20220126_111712.jpg 20220126_111736.jpg

  2. #2
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    Default

    Unlikely to be successful Steve. Just too much mass difference between the body and the broken bit. I suggest brazing to fill the entire missing piece and then redrill and retap the new hole. You will have to preheat the section of casting, but only to a couple of hundred degrees. Then use either silicone bronze and a tig, silicone bronze wire in a mig, or ordinary bronze filler wire with flux and an oxy set.
    You can weld cast iron with nickel rods, but again, you will melt the little piece before you have enough heat in the big casting to make a good weld....
    Wrap the whole thing in some pink bats as soon as you finished brazing and then let it cool down slowly by itself. Maybe a few hours should have it evenly cooled.
    Cheers, Joe
    retired - less energy, more time to contemplate projects and more shed time....

  3. #3
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    Default

    Hi,
    Unless you are a real masochist just do as Joe recommends.

    It is a simplest and easiest method of repair.

    Grahame

  4. #4
    Join Date
    Jul 2011
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    Default Itís actually quite easily done

    Iíve done several repairs like that, on old boat engines and machines.
    vee out the crack
    clean it off really well
    Use a stick welder with a STAINLESS rod
    reverse the polarity to have positive on the earth and negative on the electrode
    pre heat the parts if you can, I just use a propane torch or similar, sometimes just put them in the oven
    weld them up in stages but not too slowly once youve got heat there get it done.
    clean off welds.

    This has been successful for me lots of times.

  5. #5
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    Default

    Quote Originally Posted by Grahame Collins View Post
    Hi,
    Unless you are a real masochist just do as Joe recommends.

    It is a simplest and easiest method of repair.

    Grahame
    I can assure you, that I am not...lol
    Not the 'easiest way' is very easy for me and the job. Don't think its worth it.

  6. #6
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    Default

    Have a look at this video. It shows repairs to castings of an engine that operated in Australia.
    https://www.youtube.com/watch?v=JHCXMexB5B8
    Lots of heat and skill involved.

  7. #7
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    Default

    You can't just fill the broken bit with something like Devcon (or JB weld)? - perhaps drill a hole or two at an angle to allow some wire 'reinforcement'?
    A lick of paint and only you (and hundreds of us on the forum) will ever know...

    Michael

  8. #8
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    Quote Originally Posted by Handyjack View Post
    Have a look at this video. It shows repairs to castings of an engine that operated in Australia.
    https://www.youtube.com/watch?v=JHCXMexB5B8
    Lots of heat and skill involved.

    Thank you for posting that particular video.That cast iron fusion welding with oxy acetyelene is exactly what I did as a apprentice at Accurate Welding Works, South Brisbane circa late sixties.

    The only minor difference was that the head of the welding nozzle was provided with a water jacket.The nozzle was plumbed with copper pipes back towards the rear of the torch where the supply and return rubber hoses were connected for the water cooling system. The really important thing was to ensure that the torch was always set neutral and never allowed to creep towards a carburising setting. The carbon hardening effect was enough the destroy stones on the cylinder head grinder.


    The video in no way conveys to the viewer the huge amount of heat held in the casting.

    They used 50mm (2") diameter tubes for the gas burners.

    The lighter jobs like CAT 4 cyl diesel heads were able to be lifted out of fire into a brick bench and welded. They had a tendency to crack in the injection chambers.
    Cylinder heads were plugged and the inlets and tested with kerosene for leaks.

    If you were to place a non cooled welding nozzle in the chamber it would crack and the nozzle backfired in no time.

    The heavier items meant that you switched off the burners and welded the item while it was in the firepit at floor level.


    Overall it was a very physically demanding job.

    Thanks
    Grahame

  9. #9
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    Jul 2021
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    Central NSW
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    Default

    No such thing as canít.
    have used weld all rods for small cast repairs - which turned ok. Once on a pulley and another on a stove handle that was broken in 2.

  10. #10
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    Quote Originally Posted by Michael G View Post
    You can't just fill the broken bit with something like Devcon (or JB weld)? - perhaps drill a hole or two at an angle to allow some wire 'reinforcement'?
    A lick of paint and only you (and hundreds of us on the forum) will ever know...

    Michael

    I've done just that. Without the paint....Its behind a plate...lol

  11. #11
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    Quote Originally Posted by Mugwelder View Post
    No such thing as canít.
    have used weld all rods for small cast repairs - which turned ok. Once on a pulley and another on a stove handle that was broken in 2.

    Thanks Mugwelder...

    I should clarify that 'can't' is a shortened version of 'I can't be bothered stripping the bandsaw down completely to try and weld a small piece of cast back in place, assuming it doesn't crack when it cools as I don't have the gear to slow cool it, paint it and then reassemble .....'

    I just don't have the time.

    If I was going to do that, I'd probably try to braze it, but its still alot of work for very little gain.

  12. #12
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    Default

    Welding cast iron with stick is usually Ok if the break is like this one.By that, I mean its location relative to the remainder of the piece.
    This one is a corner and of relatively simple, meaning there's not a complex structure of thick and thin.

    Never assume that all cast iron is able to be welded. Ido not believe I have ever suggested that Oxy acetylene fusion is the only way to repair a break or a crack.

    When its something like a spoked wheel or a complex web thick to a thin structure, it becomes a very different job.

    Add to this, the fact that there are several different groups of cast iron with some of them that can't be welded at all, it can very very difficult indeed.

    Grey cast iron is the most common type but even that type varies with carbon % between different foundries.

    Identifying what you have and how to deal with takes some experience and knowledge.

    Merchant bar has a carbon % of around .03%, but cast iron is super saturated with carbon content up to 4%.

    Add to this that some can not even tell the difference between cast iron against cast steel. Steel even cast steel is relatively malleable and can stretch and twist and long time before

    fracture occurs.

    Cast iron bears compression well but not tension . That is why when electrodes are used nickel based ones work fairly well because the nickel or nickel alloy can take up the contraction to a certain extent in a rapidly cooling piece of red hot ,rapidly cooling CI. Not all attempts at cast iron repair are a resounding sucess.

    Funny that you do not seem to hear about them on utube at all.

    Grahame

  13. #13
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    Quote Originally Posted by Mugwelder View Post
    No such thing as canít.
    have used weld all rods for small cast repairs - which turned ok. Once on a pulley and another on a stove handle that was broken in 2.
    Hi Mugwelder

    This is meant as no criticism of you but is meant as a heads up for anyone considering the use of these electrodes- if you meant ALLWELD

    I am not even sure ALLWELD are still available but what can happen with these electrodes is that the flux covered deposit contracts and flicks off the still extremely hot flux. if you have some ALLWELD electrodes and are intending using them please be aware of the following.

    I was wearing all the kit including Safety glasses. I completed the bead and flicked the shield up to see. Thirty seconds later the a portion of flux was expelled with enough force to hit my forehead and drop down behind the safety specs. It fell across the eyelids of my left eye.

    It was a hospital job to separate the flux that fused my eyelids together. I was very lucky that that my eyes were not affected.

    Eyes aside ALLWELD were a plik of a rod for flux pieces splitting off for a long time after ordinary stick welding flux cooled down and could be chipped. It was common place for them sticking to other body parts as well.

    I have not thought about this incident in years but is was thinking of the ALLWELD name that triggered this. The electrode deposit does the job -no worries there but watch out for the flying flux- quickly say that 3 times when your drunk


    Grahame

  14. #14
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    Default

    I have been using Weldall for years, never experienced the problem you mention although "All Weld" may be a different kettle of fish

    PA280023.jpg

  15. #15
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    Thanks China,
    It has been forty something years , so maybe they don't make them or had changed the formula for the flux.

    I know I am a packrat and tend to keep electrodes a long time. I thought there maybe those who do the same.

    I got archeological and unearthed some Magna 303-s in my electrode cupboard the other day.They were circa late 80's.

    All good sealed up in a biscuit tin.

    Grahame

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