Corrosion Evaluation of Body in White Bimetallic Joints

This scientific article deals with cyclic corrosion testing of bimetallic joints in order to describe the influence of different surface treatment as a protection against galvanic corrosion on bimetallic materials. Multi-material body parts joined with advanced manufacturing technologies are used to achieve the required car properties. Metallic materials have different values of electronegativity and joining increases the risk of corrosion. Different types of coatings are used to prevent galvanic corrosion, but each increases investments and costs. Galvanic corrosion affects the lifecycle of the car. Cyclic corrosion testing provides replicable results to estimate the range of corrosion in a real environment. Test specimens from different materials were riveted and treated with various surface treatments. The method and design of samples preparation is unique and reflects the reality more than current methods. It has not yet been published in any literature. The corrosion test was performed for 6 weeks. Samples were subjected to a salt mist with temperatures of 25 °C and 50 °C, wetting and drying phases. The samples were evaluated according to the standard EN ISO 4628-1:2016. Microscopic and energy-dispersive analysis were performed. Tests have shown considerable galvanic corrosion on uncoated samples. On the samples with ecoated surface galvanic corrosion was not recorded.