Tips to welding cast steel

  1. Mini Machines Member

    Messages:
    15
    Location:
    Norway
    Hi

    I'm fixing an tiltrotator for my excavator where the tilt is broken of the rotor housing, the housing is made of cast steel and as I understand it's ok to weld.

    I've tried welding it a little with my Mig welder but it's only 150 amp so it's not enough, so I'm using my stick welder instead.
    But after trying with the mig I could see that the weld did crack so I need to figure out how to weld it without cracking.

    I'm planing to preheat and let it cool down slowly, I bought some Esab OK 48.15 rods that shud be good with tension as I could reed.

    Is there any other good tips for welding cast steel?
     
  2. Wonderweaver

    Wonderweaver Member

    Messages:
    274
    Location:
    Manchester
    Yes everything is good except the rods these are not cast iron rods.
     
  3. Mini Machines Member

    Messages:
    15
    Location:
    Norway
    Yes but the rotor is cast steel not cast iron, so than you don't need special rods as I understand.
     
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  4. Wonderweaver

    Wonderweaver Member

    Messages:
    274
    Location:
    Manchester
    Ok if it's cast steel then hold on for others.
     
  5. Paul.

    Paul. Moderator Staff Member

    Messages:
    6,030
    Location:
    Northampton. UK
    Cast steel should stick weld without any drama using ordinary electrodes, are you sure its cast steel and not cast iron?. try a spark test with a grinder, cast iron will give a dull red spark, compared to cast steel and mild steels which give a much brighter spark, use a piece of known steel to see what colour you are looking for,
     
  6. Munkul Member

    Messages:
    555
    Cumbria, UK
    Sounds like you have a good plan if it is indeed cast steel and not cast iron. Pre-heat, multi-run welds and cool naturally would be my choice, just to cover all bases.
     
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  7. Mini Machines Member

    Messages:
    15
    Location:
    Norway
    Engcon confirmed that it was cast steel, but I will do the grinder test since it cracked when I tried with the MIG.
    I have ordered some rods for cast iron since I tought it was cast iron first.

    Hope I get time to try welding it this week.
     
  8. Richard.

    Richard. Member

    Messages:
    18,005
    Location:
    Cambridgeshire
    It’s possible it’s cast steel and the reason for cracking was simply down to the fact the mig weld was probably too cold and the cooling rate too fast. Do a spark test as Paul suggests before buying expensive nickel rods. If it’s cast steel then I’d suggest a 150-200°c pre heat held and maintained through out welding and slow cool down over a number of hours afterwards to stress relieve the steel and keep the cooling/contraction rate slow as possible. Weld with low hydrogen electrodes.
    If it’s cast iron you want to be welding it stone cold and do a little bit at a time allowing each weld to completely cool before striking up again. It’s recommended to peen the weld straight after welding to stress relieve it locally. However I’m not sure tbh how much good that actually does. You want a high nickel/iron rod specific to cast iron repairs but not cheap so do the test first.
     
  9. Memmeddu

    Memmeddu Member

    Messages:
    838
    Location:
    Italia Sardegna
    OK48.XX should be 7018 but they are not all the same rod they are different and suitable for different applications ,I was reading this afternoon on an Italian group about,there are also ok 48 that are NOT low hydrogen rods
    As @Richard. Says you should have to preheat at a certain temperature
    You have to gouge the cracks , using an arc air ,a plasma cutter,a oxyfuel torch or a grinder
    If you have a needle scaler you can use it for peening the weld to help the metal to release the stresses in the joint.
    This helps a lot with cast iron ,cast steel doesn't require to much effort but this procedure can't damage it so... why not?
    Can you give us some photos etc?
    I do this kind of repairs quite often on lower scale (smaller equipment)
     
  10. Memmeddu

    Memmeddu Member

    Messages:
    838
    Location:
    Italia Sardegna
    309 should work ,any stainless steel should work but here we are talking about a critical component repair ,if it will break under load the boom can fall killing someone
    Spark testing is required almost to know if is steel or cast iron
    If is steel I think that 7018-H4R can be the best option
    But in any case if is cracked needs to be gouged out and drill to stop the cracks before to start welding on it
     
  11. Mini Machines Member

    Messages:
    15
    Location:
    Norway
    Thx for reply.
    First of if it fail it will not fall down and kill some one, it's still attached at the joint that tilts

    I did grind it and it's look like cast steel so it's probably because of low heat as Richard was saying it cracked under first test.

    Plan is to try and weld it this weekend, I've taken it apart again and will grind the welds from the MIG welding and than also check the sparks again.

    Thank you for ideas I have an video on my YouTube channel and will also make more videos of the repair if you wonder how it goes:ashamed:
     
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  12. TechnicAl

    TechnicAl Member

    Messages:
    6,223
    Location:
    Rotherham
    Casting is only the method used to shape it. It could be cast mild steel, cast stainless, cast alloy steel..........usually the term is used to describe low alloy steel and it is prone to cracking especially hydrogen cracking.........so as mentioned earlier, warm it up (at least 150oc) and use dry electrodes....or the MIG but try and weave and make the welds as big as possible.
     
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  13. Memmeddu

    Memmeddu Member

    Messages:
    838
    Location:
    Italia Sardegna
    Ok I was wondering that the part was only cracked but I broken you can grind it to bevel the surface
    About killing I was thinking to another part (that holds the boom attached to the excavator)
    To know if is cast iron you can also try to drill through if it makes only dust or small chips is cast iron
    About video I would like to follow your adventures I do like this kind of content

    Another thing after welding it will need to be machined with the lathe
     
  14. Mini Machines Member

    Messages:
    15
    Location:
    Norway
    I need to find something to measure the preheat with, I have an termal camera CAT S60 phone but the range is maxed out at 150.

    Broke my homemade rotator yesterday so now I need to fix that one also because I need it for making an retaining wall of natural stone and than I need to rotate stones.
    So hopefully I get time to both this weekend.

    I'm looking forward to start welding the tiltrotator after weeks with research.
     
  15. Memmeddu

    Memmeddu Member

    Messages:
    838
    Location:
    Italia Sardegna
    Heat I up until you can melt stain on it , roughly 300°C
    This does not make to much difference than it at 200°C ...
    Advice switch on the welder before to start heating up the workpiece
    Use 7018-H4R heated up to 350°C if you can
    Chamfer the work piece
    I can't see how much thick is but if is more than 8 or 10mm you can use 3,2mm rods 105 to 125A should work great because the work piece is warm
     
  16. Mini Machines Member

    Messages:
    15
    Location:
    Norway
  17. Memmeddu

    Memmeddu Member

    Messages:
    838
    Location:
    Italia Sardegna
    Liked the video and subscribed because I want to see how it goes
    But essentially what's the result?
    Have you spark tested it?
    Is cast iron or cast steel ?
     
  18. Mini Machines Member

    Messages:
    15
    Location:
    Norway
    It is cast steel, and when I got the heat in it, it welded just fine :D
    I got an crack in the second weld i did but I'm sure I preheated it to little, because after that I probably got enough heat in it from the welding and it welded just fine.
    I also packed it in for bringing the heat down slowly.

    I probably need to spot weld some after grinding but than I will heat it up a lot more before starting to weld.

    IMG_20190901_215427.jpg
     
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  19. Memmeddu

    Memmeddu Member

    Messages:
    838
    Location:
    Italia Sardegna
    Grind the cracks again make holes and repeat the process
    Now I understood which piece it is , isn't a structural part but is better be confident that it will not gonna brake again , because if the crack will extend and it falls apart (bigger section ) I think that is possible that the bucket can fall causing problems
     
  20. Mini Machines Member

    Messages:
    15
    Location:
    Norway
    Here you can see how it went welding it, finished it up yesterday.

    Thank you all for the help and tips
     
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