some dude came and spoke to our school's chapter of the AWS on this relativley new process called "friction stir" welding. they basicly spin a little "bit" through the metal and stir the metals together. They are getting results of about 4000 Pounds more tensle strength than with arc. He was telling us that a few weeks ago his company accendentally dug the bit in too deeply and kissed the surface of the steel plate the aluminium was sitting on. It wound up welding the two together with a tensle strength comprable to that of steel to steel. His company it trying to recreate the same results on purpose. I was impressed. Check it out on the web, its mad interesting
I used 1/4" aluminum to back up the welding over of some holes left from drilling out spot welds in my rebuild. The aluminum got slightly burnt but was hardly even pitted and certainly didn't stick to the steel at all. I was able to easily weld the holes closed and they were about 5/16" to 3/8" diameter.
i know they have a plant in erie pa but that is as far as i know. I was given some product by a friend and he bought it at a marina. that is all that i know. They stick the stuff together though. unreal.