http://www.alcotec.com/us/en/support/up ... hart-2.pdf
Sorry if this has already been posted somewhere before(in which case maybe this should be a sticky/posted on the main page). I noticed more than question relating to welding differant aluminum alloys together, and with what filler metal to use. This chart will answer most of em.
The instructions are at the bottom. My welding instructor passed this chart out to the class (unfortunately mine was stolen with my snappack outta my car). Basically you look up what two alloys you want to weld together, and what filler metal you want to use to get the specific properties out of the finished weld. The A's and B's are how well the finished weld would rate on that characteristic(like tensile strength or service life).
Enjoy!
