More specific questions might help.....

I tig weld with this filler, and onto this base metal, but not on it in sheet form.

I have heard about maybe pre-heating my base metal.The problem I'm having is that when I'm done running my bead,I'm chasing cracks.All beads are stitched and staggered not concentrating on one area.This is probably the MOST frustrating project I have worked on.Maybe heat treating?Thanks