Influence of austenitisation temperatures during hot stamping on the local electrochemical behaviour of 22MnB5 steel coated with hot-dip Al-Si

•Hot-stamping austenitisation temperature is critical to Al-Si coating’s morphology.•System’s local electrochemical behaviour varies with austenitisation temperature.•Iron enrichment through diffusion causes overall ennoblement of the Al-Si coating.•The driving force for cathodic protection reduces...

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Bibliographic Details
Published in:Corrosion science 2021-09, Vol.190, p.109673, Article 109673
Main Authors: Couto, Camila Pucci, Revilla, Reynier I., Politano, Rodolfo, Costa, Isolda, Panossian, Zehbour, De Graeve, Iris, Rossi, Jesualdo Luiz, Terryn, Herman
Format: Article
Language:English
Subjects:
Aluminum
Austenitisation temperature
Boron steels
Cathodic protection
Electrochemical analysis
Electrochemical behaviour
Hot dip aluminizing
Hot dipping
Hot stamping
Hot-dip Al-Si
Immersion coating
Morphology
Scanning kelvin probe force microscopy
Silicon
Substrates
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Summary:•Hot-stamping austenitisation temperature is critical to Al-Si coating’s morphology.•System’s local electrochemical behaviour varies with austenitisation temperature.•Iron enrichment through diffusion causes overall ennoblement of the Al-Si coating.•The driving force for cathodic protection reduces with austenitisation temperature.•The need for local investigations is highlighted by the complexity of the system. Scanning Kelvin probe force microscopy was used to evaluate the effect of austenitisation temperatures during hot stamping on the local electrochemical behaviour of 22MnB5 steel coated with hot-dip Al-Si. A variation in the austenitisation temperature around 50 °C substantially altered the coating morphology as well as the local electrochemical behaviour of the system (coating/steel). Both coating layer and steel substrate became nobler as the austenitisation temperature increased. The former was due to the overall iron enrichment while the latter was related to the microstructural transformation during quenching. Therefore, the driving force for cathodic protection decreased as the austenitisation temperature increased.
ISSN:0010-938X
1879-0496
DOI:10.1016/j.corsci.2021.109673