Metallic coating development takes a long time and is expensive because of the long-term corrosion testing in both lab and outdoor conditions. So, simulation-assisted engineering could lead to significant acceleration and cost-reduction of the development of new coatings.
That is why OCAS joined the RFCS AtCorAS project on ‘Modelling of atmospheric corrosion of steel protected by aluminium-based alloys, applied by hot dip processing’. The focus of the project was to investigate and understand the mechanisms of atmospheric corrosion.
Using the hot dip process simulator, OCAS supplied metallic coatings with various compositions. Other partners in the project then used this input to develop the model. Finally, the model was validated on the basis of the outdoor exposure and accelerated corrosion testing results obtained by OCAS.
The model that was developed will enable us to predict the corrosion behaviour of steel protected by Al-based alloys. In addition, by allowing us to simulate the impact of metallic coating composition under various conditions, use of the model will reduce experimental testing.
Based on the analysis of corrosion products found at different locations at the cut-edge, a map of corrosion products distribution was made. Results from simulations showed a very similar trend. This has led to a fundamental understanding and quantification of the corrosion processes taking place.
Beyond standard materials testing
Extensive interactions between experiments and modelling demonstrates how modelling can contribute to the design of new metallic coatings for the protection of steel. The link between corrosion mechanisms and corrosion performance is made by the combination of electrochemical data, surface and corrosion product characterisation,
Thanks to the project, we’ve acquired profound knowledge of the effects of the different alloying elements of the hot dip coating on the microstructure. The project also showed the electrochemical reactivity of the different aluminium-based alloys in chloride and chloride-free environments.
“We now have a much better understanding of the role of the metallic coating and electrolyte composition in the corrosion behaviour of coated steel. This opens perspectives that go beyond standard materials testing in steel product development.”