Brande of Nickel Cast Iron Rod ?

Here's mine. Choose the proper electrode based on these factors. Want machinability? Color match? Ductility? Welding cast to cast or cast to steel? Casting new or contaminated with use?

In your case you want a rod with ductility that welds dirty. I assume you do not have a good way to preheat.

First terminate the crack by drilling 1/8" holes at both ends or by welding a small piece of steel cross ways and just beyond both ends of the crack. Grind the top clean on both sides of crack so weld metal will blend in well.

As Fred indicated, preheat in oven or on BBQ grill to around 300°F soaked. Do not carry the heated casting outside. Prior to welding, prep the area with an exothermic gouging rod such as our #1250. Use 1/8" electrode at 150 amps AC.

For high strength and ductility, use an electrode like the #521 arc brazing. This is not as crack sensitive as nickel when cold welding cast iron of unknown chemistry.

Use a 3/32" electrode at 75 to 80 amps. Lay stringer beads about 1/2" to 3/4" long. Do not weave. Also, back up before breaking the arc so you don't leave an undercut at the end of the bead. Peen between passes as Fred said.

You may also employ the backstep method. This is done by laying a bead in the middle of the crack, then on one end, then on the other end, and going back to the center. Repeat until all the welds meet.

Do not let the cast iron get too hot to touch. By that I mean so hot you can't touch it for about a second. You don't need to be able to lay your hand on it.

Finally, bury the casting in dry sand, cat litter, vermiculite, powdered redi-mix, lime, fiber glass, kao wool, etc. Or, slowly bring the finished weld back to temp soaked, and slowly turn down the heat over 3 hours or so until below critical temp.

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Steve