A study on chloride induced depassivation of Fe-P-C-Si and Fe-P-C-Si-N steels in simulated concrete pore solution

The corrosion behaviour of high phosphorous steels containing varying amounts of silicon and nitrogen was studied by potentiodynamic polarization, linear polarization resistance (LPR) and electrochemical impedance spectroscopy (EIS) measurements. The morphology of a steel specimen tested in chloride...

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Bibliographic Details
Published in:IOP conference series. Materials Science and Engineering 2018-03, Vol.330 (1), p.12014
Main Authors: Mehta, Yashwant, Chaudhari, Gajanan P, Dabhade, Vikram V
Format: Article
Language:English
Subjects:
Carbon steels
Chlorides
Corrosion
Electrochemical impedance spectroscopy
Equivalent circuits
Free surfaces
Inclusions
Linear polarization
Morphology
Nitrogen
Pitting (corrosion)
Scanning electron microscopy
Slaked lime
Spectrum analysis
Steel
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Summary:The corrosion behaviour of high phosphorous steels containing varying amounts of silicon and nitrogen was studied by potentiodynamic polarization, linear polarization resistance (LPR) and electrochemical impedance spectroscopy (EIS) measurements. The morphology of a steel specimen tested in chloride containing concrete pore solution was studied using scanning electron microscope (SEM) and the elemental distribution at the pitting corrosion area was investigated using electron dispersive spectroscopy (EDS). The results showed that the capacitance increased and resistance declined with immersion time in Ca(OH)2 solution containing 0.1% chloride for plain carbon steel. The opposite was observed in the case of the high phosphorous steels. The potentiodynamic polarization and LPR results complement the EIS findings. Corrosion behaviour could be described with an equivalent circuit having two time constants. The creation, expansion and degradation of the passive layer were discussed with the help of the equivalent circuit elements. The SEM-EDS studies revealed that MnS inclusions at the surface could have a role in the initiation and growth of pits and that phosphorous was present at the pit free surface of the steel.
ISSN:1757-8981
1757-899X
DOI:10.1088/1757-899X/330/1/012014