cast iron

  1. Ami

    Ami Member

    Messages:
    93
    Location:
    Israel
    Hey guys,
    I have zero exp with cast iron, but a guy I work with asked me to weld a cast iron plate from his fire place that cracked right down the middle. Is that doable?
     
  2. brokenbiker

    brokenbiker Member

    Messages:
    10,437
    Location:
    Llanbobyll, south wales
    Anything is doable. Cast iron is prone to cracking so needs a pre heat and a slow cooling time. Not sure what tig rod would be best, I always stick welded iron and used a stainless 309 rod
     
  3. piman Member

    Messages:
    1,739
    Location:
    Oswestry Shropshire
    Hello Ami,

    I've done quite a few bits of cast iron, even quite thin sections quite successfully. I use an MMA with dedicated cast iron welding rods, no pre heat but short lengths of welding so as not to heat up the job too much.

    Alec.
     
    magnet likes this.
  4. gordon stephenson

    gordon stephenson Forum Supporter

    Messages:
    6,879
    Location:
    Skelton in Cleveland U.K.
    No practical knowledge, but the usual method of repair for the less experienced welder is usually brazing, Not invisible, but will probably get the job done.
     
    brightspark likes this.
  5. Screwdriver

    Screwdriver Member

    Messages:
    6,496
    UK London
    I bumped into this video when looking for cast iron repair:



    One thing though, if you melt the cast iron it goes glass hard - you won't be filing that off. Braze is best imho for all sorts of reasons.

    S.
     
  6. Tig brazing works well on cast iron, and there seems little need to pre heat or post cooling.
     
  7. Richard.

    Richard. Forum Supporter

    Messages:
    18,350
    Location:
    Cambridgeshire
    Nickel/iron based filler works very well for tig welding cast iron.
     
  8. Ami

    Ami Member

    Messages:
    93
    Location:
    Israel
    Can you elaberate please? What rod? should I bevel? Would a SS filler work?
     
  9. Richard.

    Richard. Forum Supporter

    Messages:
    18,350
    Location:
    Cambridgeshire
    The FeNi rods I was referring to are good for that exact job but cost an arm and a leg as you'd expect from a nickel based filler. I personally wouldn't use stainless filler but if that is the route you chose then a 312 would be most suited as it's designed for dissimilar and difficult to weld materials.
     
    Tigman likes this.
  10. Parm

    Parm Oh how I’ve missed my play pen this year

    Messages:
    12,349
    Location:
    Towcester
    I'm a complete novice and repaired a cast iron Dutch oven pot with a big crack, pre heat on a boiling ring, braze with oxy propane and then cover in an old fire blanket to cool slowly. I'm quite proud of the fix and after a few uses crack is almost invisible
     
    brightspark likes this.
  11. Tinbasherdan

    Tinbasherdan Bodger in chief

    Messages:
    5,306
    Location:
    Bolton, England
    Just built up a cam/pulley using mma rods, tried tig but the heat was just too focused
     
  12. Rrunnach

    Rrunnach www.interventiontechnolog y.com

    Messages:
    1,005
    Location:
    edinburgh
    I have found doing similar types of repair have been completely unsuccessful, mainly down to cast specification being of the type that does not lend itself to weld repairs.
     
  13. hotrodder Member

    Messages:
    4,587
    SE England
    http://www.mig-welding.co.uk/welding-cast-iron.htm , http://www.twi-global.com/technical-knowledge/job-knowledge/weldability-of-materials-cast-irons-025/ and http://www.esabna.com/euweb/oxy_handbook/589oxy15_1.htm which is more about traditional methods using oxyfuel

    None of those sources mention stainless filler wire or electrodes because stainless = lots of chromium and very little carbon. Cr has a high affinity for C and the result is 'kin hard & brittle chromium carbides. Cast iron is way higher in C than any flavour of steel...
     
    Paul G likes this.
  14. Richard.

    Richard. Forum Supporter

    Messages:
    18,350
    Location:
    Cambridgeshire
    If it's gonna be done with mig I'd still suggest an Ni based filler to give the best results.
     
    Kayos and Member 66062 like this.
  15. arceyered Member

    Messages:
    310
    Location:
    Wolverhampton England
    One other tip is to do it in 1/2 to 3/4 inch lengths in different places as soon as you have welded a short length peen it rapidly with a ball point hammer to relieve the stress.
     
  16. Ami

    Ami Member

    Messages:
    93
    Location:
    Israel
    So I'm understanding no preheat, keep the temp down and minimize stress? I cant braze so I have to weld. I have er-70 ,308, 309, 314 and fagersta 307 (used for armor) or electrodes zika 6013. what would you go with?
     
  17. Screwdriver

    Screwdriver Member

    Messages:
    6,496
    UK London
    While I was researching the same sort of thing one of the things I saw was that welding cast iron is only successful about half the time. Depends exactly what other rubbish is in the casting and if it's unsuitable for welding, it won't weld no matter what you do. Whatever you do, you should at least test a small area first. Might also be a good idea to mechanically secure the join with a few tabs screwed in behind it if you insist on welding.
     
  18. TechnicAl

    TechnicAl Member

    Messages:
    7,802
    Location:
    Rotherham
    I know that man. He used to work for Lincoln. He was Lincoln through and through so I wonder why hes left them....curious
     
  19. arceyered Member

    Messages:
    310
    Location:
    Wolverhampton England
    The other thing you can look at is stitch locking, google stitch locking cast iron? We have used this method on machine beds very successful.
     
  20. hotrodder Member

    Messages:
    4,587
    SE England
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