weldig on cast iron

[yotarover]

what rods are best for welding cast iron? i know that when it gets hot then cools it cracks then splits and pops. i've used a OA torch to preheat then welded with special rods. nothing seems to work so far

[geezer]

Use a nickel rod with low heat, keep your weld length to 1/2 to 1 inch long and use a ball peen hamer to relive the stress, or use a cast rod again keeping the weld length short to prevent stress cracks. Use light bead build up and clean and chip before you apply a second bead on the buildup

[Zoomie]

Aaron, take a look at www.weldingtipsandtricks.com Mr. Jody Collier discusses welding on cast at some length. You might get ideas from him as to how to proceed. You can also email him directly if you need specific questions answered.

Z

[jakeru]

There are quite a few different techniques I've read about for welding cast... bronze filler rod vs nickel vs. stainless steel vs. cast iron filler rod, pre-heat, post-heat, peening weld with hammer.

I'm planning on tackling welding to a gray cast iron exhaust manifold here pretty soon.

I'm planning on attempting it with "Nickel 55" (a 55% nickel) rod and some pre/post heat with a "weed burner" oxy-propane torch. The 55% nickel rods (with balance material nearly all iron) are designed specifically for joining cast iron to other cast iron or to steel, and are readily available at my local welding supplies in 1/8" flux covered stick welding electrode format.

I haven't decided yet if I'm going to:
A. stick weld it
B. TIG weld it using the stick electrode (including flux) as a filler rod
C. TIG weld it using the "bare" stick electrode (flux manually removed) as a filler rod.

I sourced some bare "nickel 55" TIG filler rods via mail order, but found they were quite a bit more expensive, and with twice as high of a minimum ordering quantity than the stick electrodes of the same alloy composition.

[sportbike]

Cast iron welding by preheating the whole part in an oven to about 300 degrees F, doing the welding (re-heating if multi passes or a long weld is needed), then putting the whole thing in a vermiculite filled container. Vermiculite is available for use in garden soil and is almost like small styrofoam packing peanuts. The vermiculite insulates the part and basically allows it to cool slowly.

Not sure I need to mention this, but DO NOT USE STYROFOAM PACKING PEANUTS :-)

John