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Due to the inherently superior corrosion resistance of aluminum compared to automotive steels, phosphating and electrocoating are not necessarily required to provide good corrosion protection to aluminum intensive vehicles. This allows the potential for significant cost savings in the overall finishing process by eliminating these steps. Advantage can also be taken of the movement towards the use of powder primer surfacers to reduce solvent emissions in that the powder coating can be applied directly to a suitably pretreated aluminum surface. Pretreatments which are optimized for aluminum and much simpler to control than phosphating were chosen for trials based upon discussions with chemical suppliers. In this paper, the adhesion and corrosion characteristics of these selected pretreatment/powder primer systems were compared to standard phosphated and electrocoated AA6111 automotive closure sheet.

Weld bonding of aluminium autobody structures offers automotive vehicle manufacturers the opportunity of achieving significant weight reduction, compared to equivalent steel structures. Further, this is achievable using volume production manufacturing methods. This paper considers all key aspects of the weld bonding process, in particular the equipment requirements and the factors that are important in reliably achieving satisfactory structures. Methods of minimising damage to the adhesive bondline and assessment of spot weld quality are discussed. Using experience gained from extensive weld bonding trials, suitable parameters for robust weld bonding are recommended.

Efforts towards weight reduction are leading towards increasing use of aluminum components on automobiles. Although aluminum on its own has inherently superior corrosion resistance to steel, galvanic action between the aluminum and steel or galvanized parts can lead to severe corrosion. Straightforward and effective methods of preventing galvanic corrosion from the subject of this paper. Since many aluminum components are connected to steel structures by mechanical fasteners, protective coatings on fasteners were evaluated as well. Galvanic test couples were prepared in a manner simulating typical automotive assembly conditions while incorporating features which would lead to enhanced corrosion. A variety of chemical treatments and coatings on the fasteners as well as barriers between the dissimilar metals were evaluated for corrosion prevention between the aluminum and cold rolled or galvanized steel. Comparison between neutral salt spray and cyclic corrosion tests is provided.