Mig welding cromemoly wrc roll cage?

  1. whensparksfly Member

    Messages:
    554
    Location:
    ireland
    I seen a Mig welding cromemoly wrc roll cage lately always been told to tig never mig what you all think it was a factory car
     
  2. PhillipM

    PhillipM Member

    Messages:
    1,803
    Rotherham
    Was it actually Chrome-moly, or was it T45/15CDV6? The latter are no problem for welding.

    There's no issue mig welding chrome-moly tube anyway, the issue is it needs heat treating after welding. TIG could be argueably worse as it puts more heat in. Some of the american rules say you must TIG weld it but I've never seen anything to back up their reasoning there.
     
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  3. whensparksfly Member

    Messages:
    554
    Location:
    ireland
    I'm unsure on exact material what process do you use for mig on cromemoly?
     
  4. whm_fab

    whm_fab Motorsport fabrication

    Messages:
    343
    Location:
    ireland
    unless it came from the U.S of A, its more than likely not cromoly, but T45.

    as philip says cromoly needs to be heat treated after migging, and depending on thickness/heat input/how critical the aplication is, Tig also.
    Cromoly in the HAZ (not the weld itself) can become weakened and prone to cracking depending on how much heat has been put into it
     
  5. Ruffian Member

    Messages:
    1,671
    Location:
    Devon UK
    UK roll cages are usually t45 or CDS,
    Rather than cromoly. Not saying it wont be,

    When we were welding in safety devices cages they did prefer mig welded for some reason but cant remember why.
     
  6. Could have been because MIG has a lower heat input than TIG so there will be less metallurgical damage
     
  7. chevy2

    chevy2 Member

    Messages:
    1,631
    Location:
    Herts.
    4130 chromemoly is used in the UK but the vast majority is for drag race cars,
    i've used it a fair bit,
    The general consensus, obviously depends on where you read it is that under around .120"wall or 1/8" in old money is that it wont need heat treating,
    Most drag race stuff is under that wall thickness on tubing with.083" wall normally the max.
     
  8. Brad93

    Brad93 M J B Engineering

    Messages:
    5,910
    Location:
    Essex
    You can tig weld CrMo 4130 up to about 3mm/4mm thick without heat treatment if you use undermatching filler metal and maintain a decent heat input which locally anneals the HAZ.

    ER70S2 or ER80Sd2
     
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