On Tuesday, November 24, 2015 at 2:07:58 PM UTC-5, wrote:

Hey Terry, if you haven't yet welded the grate I may have some info to
help. I found an unopened package of the rod I used in the past for
stick welding cast iron and it is a Stoody product called CASTWELD 55.
It was pretty easy rod to run so even though you said you are better
at TIG than Stick you should be able to weld with the stuff. Or, you
can just remove the flux and use it as TIG rod. I have done this and
it worked OK. But it really works better for stick welding.
Eric

I sent Terry some invar 42 , genuine Boeing surplus. The post office says it should be there right after Thanksgiving. Invar 42 is 42 % nickel so should not be drastically different from a 55% nickel rod. At least that was my thoughts when I bought it.

Dan