Grant, I thought one could ball tungstens with just a piece of scrap
iron. I will let you know if I ever cut it up.

That really doesn't work. You want a metal that is as conductive as possible,
both electrically and thermally. Short of precious metals, copper is the best
you can do.

You can also use a chunk of copper as a backing bar for welds. I've used blocks
of scrap aluminum for this too.

Grant