How To Weld Aluminum And Steel. In this case it would be better to actually bolt the parts together. Coat the steel prior to welding.
Now it may sound like there is. Assemble the joint and cover it if you wont be welding it immediately. But the gas needs to be completely inert.
While solid-state joining processes like friction stud welding and flash butt welding can join aluminum and steel together you will not be able to do this using GTAW or GMAW.
While a weave technique commonly is used to weld steel it should not be used with aluminum. Arc welding the two metals together would also create a brittle compound and would not create a strong fusion. One method is to coat the steel with aluminum. In this case it would be better to actually bolt the parts together.