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A body shell manufactured entirely of aluminum alloys is generally regarded as being insensitive to corrosion. The following paper confirms this assessment but specific types of corrosion affecting aluminum have to be avoided. The experience on which it is based includes vehicles with aluminum components driven in the field by customers, but is mainly derived from corrosion testing on specimen components and complete vehicles performed during the course of development. The most critical type of damage occurring is contact corrosion caused by other metals and conductive plastics. If the conversion coating on the metal is unsuitable, paint adhesion is insufficient and the characteristic aluminum filiform corrosion will start to form. Corrosion in crevices and beneath accumulated dirt is also likely to occur. This paper describes suitable protective measures, and also refers to repair techniques designed to avoid corrosion.

This paper compares the standard of corrosion protection on current European passenger cars with the levels achieved six years ago. Progress is particularly apparent on the more recent car designs. This gives credibility to the up to 10-year warranties covering rust perforation. The various manufacturers have different approaches to the question of corrosion protection, and this report explains the various methods used. Environmental problems and increasing competition in the market will have a considerable influence on anti-corrosion materials and processes over the coming decade.

Corrosion is still the most frequent cause of deficiencies on cars over 5 years old. Life expectancy can be increased by approximately four years if double-sided galvanised sheet metal is used, if the vehicle is suitably designed to avoid corrosion and if currently available corrosion protection measures are carefully applied. The theories behind the corrosion protection properties of galvanised steel, i.e the barrier effect and cathodic protection are discussed in detail. The paper describes how this protective effect of the zinc coating is obtained in practice, and on which areas of the body and under what kinds of corrosive exposure it is effective. The results of this research have been implemented in the production of the Audi 100/Audi 5000 and the Audi 80. The paper describes the 100% galvanised bodyshells manufactured in volume production of these models, and outlines recycling possibilities.

The resistance of passenger cars to corrosion is tested in a three-chamber system, in which the cars are subjected to extreme climatic conditions. A hydropulse installation, a roller dynamometer, blower fans and a ‘gravel gun’ firing stone chippings are used to simulate actual road use. During a 14-week test period, it is possible to obtain corrosion equivalent to that which would have occurred in 6 years of driving in a very corrosive environment.