The transpassive dissolution mechanism of highly alloyed stainless steels

I. Experimental results and modelling procedure

Iva Betova, Martin Bojinov (Corresponding Author), Timo Laitinen, Kari Mäkelä, Pekka Pohjanne, Timo Saario

Research output: Contribution to journalArticleScientificpeer-review

102 Citations (Scopus)

Abstract

The transpassive dissolution of austenitic stainless steels (AISI 316L, AISI 904L, 254SMO and 654SMO) in a 0.5 M sulphate solution with pH 2 was studied by conventional and rotating ring disc voltammetry, as well as electrochemical impedance spectroscopy. The main process in the transpassive potential region was found to be the release of soluble Cr(VI), while small amounts of lower-valency Cr or Mo species are released as well. Secondary passivation readily occurs for AISI 316L, whereas the remaining highly alloyed steels dissolve at high current densities in the whole potential range studied. The dissolution rate was found to increase in the order AISI 904L<254SMO<654SMO. Thus it can be correlated to the increase in the Cr and especially Mo content of the steel substrate. The impedance spectra contain contributions from the transpassive dissolution of Cr and secondary passivation, probably due to enrichment of Fe in the outermost layer of the surface film. A kinetic model of the process is proposed, including a two-step transpassive dissolution of Cr via a Cr(VI) intermediate and the dissolution of Fe(III) through the anodic film. The model was found to be in quantitative agreement with steady state current vs. potential curves and electrochemical impedance spectra. The kinetic parameters of transpassive dissolution were determined and the relevance of their values is discussed.
Original languageEnglish
Pages (from-to)2675-2697
JournalCorrosion Science
Volume44
Issue number12
DOIs
Publication statusPublished - 2002
MoE publication typeA1 Journal article-refereed

Fingerprint

Stainless Steel
Dissolution
Stainless steel
Steel
Passivation
Voltammetry
Austenitic stainless steel
Electrochemical impedance spectroscopy
Kinetic parameters
Sulfates
Current density
Kinetics
Substrates

Keywords

  • Stainless steel
  • EIS
  • RRDE
  • Modelling studies
  • Transpassivity
  • Kinetic parameters

Cite this

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title = "The transpassive dissolution mechanism of highly alloyed stainless steels: I. Experimental results and modelling procedure",
abstract = "The transpassive dissolution of austenitic stainless steels (AISI 316L, AISI 904L, 254SMO and 654SMO) in a 0.5 M sulphate solution with pH 2 was studied by conventional and rotating ring disc voltammetry, as well as electrochemical impedance spectroscopy. The main process in the transpassive potential region was found to be the release of soluble Cr(VI), while small amounts of lower-valency Cr or Mo species are released as well. Secondary passivation readily occurs for AISI 316L, whereas the remaining highly alloyed steels dissolve at high current densities in the whole potential range studied. The dissolution rate was found to increase in the order AISI 904L<254SMO<654SMO. Thus it can be correlated to the increase in the Cr and especially Mo content of the steel substrate. The impedance spectra contain contributions from the transpassive dissolution of Cr and secondary passivation, probably due to enrichment of Fe in the outermost layer of the surface film. A kinetic model of the process is proposed, including a two-step transpassive dissolution of Cr via a Cr(VI) intermediate and the dissolution of Fe(III) through the anodic film. The model was found to be in quantitative agreement with steady state current vs. potential curves and electrochemical impedance spectra. The kinetic parameters of transpassive dissolution were determined and the relevance of their values is discussed.",
keywords = "Stainless steel, EIS, RRDE, Modelling studies, Transpassivity, Kinetic parameters",
author = "Iva Betova and Martin Bojinov and Timo Laitinen and Kari M{\"a}kel{\"a} and Pekka Pohjanne and Timo Saario",
year = "2002",
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The transpassive dissolution mechanism of highly alloyed stainless steels : I. Experimental results and modelling procedure. / Betova, Iva; Bojinov, Martin (Corresponding Author); Laitinen, Timo; Mäkelä, Kari; Pohjanne, Pekka; Saario, Timo.

In: Corrosion Science, Vol. 44, No. 12, 2002, p. 2675-2697.

Research output: Contribution to journalArticleScientificpeer-review

TY - JOUR

T1 - The transpassive dissolution mechanism of highly alloyed stainless steels

T2 - I. Experimental results and modelling procedure

AU - Betova, Iva

AU - Bojinov, Martin

AU - Laitinen, Timo

AU - Mäkelä, Kari

AU - Pohjanne, Pekka

AU - Saario, Timo

PY - 2002

Y1 - 2002

N2 - The transpassive dissolution of austenitic stainless steels (AISI 316L, AISI 904L, 254SMO and 654SMO) in a 0.5 M sulphate solution with pH 2 was studied by conventional and rotating ring disc voltammetry, as well as electrochemical impedance spectroscopy. The main process in the transpassive potential region was found to be the release of soluble Cr(VI), while small amounts of lower-valency Cr or Mo species are released as well. Secondary passivation readily occurs for AISI 316L, whereas the remaining highly alloyed steels dissolve at high current densities in the whole potential range studied. The dissolution rate was found to increase in the order AISI 904L<254SMO<654SMO. Thus it can be correlated to the increase in the Cr and especially Mo content of the steel substrate. The impedance spectra contain contributions from the transpassive dissolution of Cr and secondary passivation, probably due to enrichment of Fe in the outermost layer of the surface film. A kinetic model of the process is proposed, including a two-step transpassive dissolution of Cr via a Cr(VI) intermediate and the dissolution of Fe(III) through the anodic film. The model was found to be in quantitative agreement with steady state current vs. potential curves and electrochemical impedance spectra. The kinetic parameters of transpassive dissolution were determined and the relevance of their values is discussed.

AB - The transpassive dissolution of austenitic stainless steels (AISI 316L, AISI 904L, 254SMO and 654SMO) in a 0.5 M sulphate solution with pH 2 was studied by conventional and rotating ring disc voltammetry, as well as electrochemical impedance spectroscopy. The main process in the transpassive potential region was found to be the release of soluble Cr(VI), while small amounts of lower-valency Cr or Mo species are released as well. Secondary passivation readily occurs for AISI 316L, whereas the remaining highly alloyed steels dissolve at high current densities in the whole potential range studied. The dissolution rate was found to increase in the order AISI 904L<254SMO<654SMO. Thus it can be correlated to the increase in the Cr and especially Mo content of the steel substrate. The impedance spectra contain contributions from the transpassive dissolution of Cr and secondary passivation, probably due to enrichment of Fe in the outermost layer of the surface film. A kinetic model of the process is proposed, including a two-step transpassive dissolution of Cr via a Cr(VI) intermediate and the dissolution of Fe(III) through the anodic film. The model was found to be in quantitative agreement with steady state current vs. potential curves and electrochemical impedance spectra. The kinetic parameters of transpassive dissolution were determined and the relevance of their values is discussed.

KW - Stainless steel

KW - EIS

KW - RRDE

KW - Modelling studies

KW - Transpassivity

KW - Kinetic parameters

U2 - 10.1016/S0010-938X(02)00073-2

DO - 10.1016/S0010-938X(02)00073-2

M3 - Article

VL - 44

SP - 2675

EP - 2697

JO - Corrosion Science

JF - Corrosion Science

SN - 0010-938X

IS - 12

ER -