go to www.weldit.com click on products, then alloy steels, then polaris aaa. I've used this wire & stick rods for welding 4140 plate to mild steel plate many times. I pre-heat, weld then let it cool on it's own. Never had a problem. Or www.rockmountnassau.com (same place)
Very impressive site. They've got alot of uniqe fillers, thats for sure.