cast iron welding

[Desert Beast]

alright ive already read the previous posts on this but i was wondering if tig welding worked for this. you all say for the most part arc works w/ nickel rod. my buddy was trying to weld my spring perch by tig welding w/ a nickel rod and right after he takes the torch away the weld starts to crack. we pre heated the cast and it still cracked. what are we doing wrong. and help is appreciated.
thanks

[River Beast]

I'm no welding expert, DB.... sounds like it's cooling off way too fast..... I had no problems with preheated Nickle ARC or preheated MIG..... no experience with TIG

Slow cooling is required.... how you do it is up to you....

[Tad]

I sure do love TIG welding, but this is one place I don't think it works very well.

I picture several problems asociated with trying to TIG spring perches onto the pumkin for SOA (I assume this is what you are doing here).

My impression is that the cast iron is sucking a tremendous amount of heat away from the weld pool allowing it to cool way to quickly.

Even if your buddy has a 400 amp TIG welder and is running 1/8" tungsten it's going to be extreamly hard to maintain a good weld (even with pre and post heating applied).

[mdill]

One other note is to "ping" the weld as it cools, the problem you fight
with cast is that it has about 0 tensile strength and is also has a almost
zilch elongation before cracking. Since the weld area gets the hottest and
the molten pool is at max expanshion the weld will try and shrink away from
the work ,(True on most normal materials) with steels that is usually not a big
issue as the will either streach or bend as the work cools, cast tends to just crack.
On cast preheat, do small welds, ping while cooling to preheat temp, do small weld
..., that usually works fro me, the more preheat and least added weld heat is
what I strive for.

Mike D.