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Predictive modeling of long‐time crevice evolution at e‐coat defects under climate chamber test conditions
Author(s) -
Bösch N.C.,
Höche D.,
Mittelbach A.,
Kainer K. U.
Publication year - 2017
Publication title -
materials and corrosion
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.487
H-Index - 55
eISSN - 1521-4176
pISSN - 0947-5117
DOI - 10.1002/maco.201609202
Subject(s) - galvanization , crevice corrosion , materials science , coating , tafel equation , corrosion , delamination (geology) , polarization (electrochemistry) , galvanic cell , galvanic anode , metallurgy , composite material , anode , layer (electronics) , electrode , electrochemistry , cathodic protection , paleontology , chemistry , biology , subduction , tectonics
The undermining of organic coatings on galvanized steel sheets is being characterized using transient finite element simulations. Galvanized steel sheets are the most widespread parts in the automobile industry. Thus, the delamination beginning from coating defects is a crucial issue to deal with. This matter is depicted through a manually brought in impairment in the coating layers down to the steel surface. Therefore, a galvanic couple is formed and mainly the less noble zinc layer corrodes and consequently anodically undermines the organic coating. In order to predict the corrosion behavior via computational simulations, an approach is developed which uses a mixture of digitalized polarization curves as well as empirical Tafel values and reveals a significant reduction in computation time. The corrosion progress is evaluated via current distributions and the resulting damage for different electrolytes, types of galvanizing and impairment dimensions. These simulations describe the progression of the corrosive anodic delamination process over several weeks and attune well to corresponding experimental climate chamber tests and offer an acceptable validity toward corrosion related surface finishing layout.