Influence of the coating by bonded arc joining of steel to aluminium

The firmly bonded joint between steel and aluminium has, so far, not been achieved successfully in joining technology. The problems of joining these metals thermally are caused by the low up to non-existing solid solubility of the metals and by the development of brittle intermetallic phases. The quality of the joints depends on many influential factors which are, sometimes, also interacting. One of those influential factors is the coating of the steel sheets. Using the example of coatings which are common and others which are unusual in automotive engineering it has been tried to demonstrate the influence on the wetting length and wetting angle of those factors with, otherwise, constant boundary parameters. The results are part of a test series which is currently carried out at the Joining and Welding Institute, Aachen.