ArtMetal

There are some very limited methods for actually welding ferrous to non-ferrous alloys. Unfortunately though, these processes do not lend themselves to the hobbyist or even most welding professionals as they typically require very specialized tooling and equipment. The most effective method that I have used involves a GMAW type process with AL wire and a dabber type wire feeder cycling at about 40 cycles per second with the welding current and voltage tuned to compliment the dabber cycle. Heat shunting is very important to limit the size of the heat affected zone and control cooling contraction in the dissimilar metals. I use water cooled copper bars on both sides of the work-pieces and joint.
Fronius, a welding equipment supplier, has at least one dabber style GMAW gun on the market, so perhaps in the future these technologies will be more readily available.

Go with cool bolts!