Effect of service exposure on KCl corrosion attack of AISI 347H FG steel

Yohanes Chekol Malede*, Kristian Vinter Dahl, Melanie Montgomery, Flemming Bjerg Grumsen, John Hald

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

The effect of ageing of AISI 347H FG austenitic steel on KCl-induced corrosion was investigated by comparing the corrosion attack on tube material previously service-exposed for 100000 h and that on an as-received tube. Cr-rich σ-phase precipitates were found mainly along grain boundaries in the microstructure of the service-exposed material, whereas no σ-phase was present in the as-received condition. Laboratory corrosion experiments were carried out using KCl-free and KCl-covered samples in a 15% (v/v) H2O (g) + 5% (v/v) O2 (g) + N2 (g) (balance) atmosphere at 600 °C for 168 h. Microstructural characterisation was performed before and after the corrosion experiments using light optical microscopy, X-ray diffraction spectroscopy, scanning electron microscopy with energy-dispersive X-ray analysis (SEM/EDX) and scanning transmission electron microscopy with energy-dispersive X-ray analysis (STEM/EDX). The presence of KCl resulted in increased attack, and the service-exposed material had increased attack compared to the as-received TP347H FG material; thus, the deepest attack was observed for KCl-covered previously service-exposed material where grain boundary internal attack occurred. The experimental investigations indicate preferential attack of the Cr-rich precipitates and the presence of chlorine at the corrosion front and Cr-rich precipitates (σ-phase) ahead of the corrosion front for KCl-covered service-exposed material. The findings suggest that service-exposed AISI 347H FG material may experience an increased KCl-induced corrosion attack caused by selective attack of the Cr-rich σ-phase.

Original languageEnglish
JournalJournal of Materials Science
Volume54
Issue number21
Pages (from-to)13787–13809
ISSN0022-2461
DOIs
Publication statusPublished - 2019

Cite this

@article{e6275b158e2940598049aad795af7c7c,
title = "Effect of service exposure on KCl corrosion attack of AISI 347H FG steel",
abstract = "The effect of ageing of AISI 347H FG austenitic steel on KCl-induced corrosion was investigated by comparing the corrosion attack on tube material previously service-exposed for 100000 h and that on an as-received tube. Cr-rich σ-phase precipitates were found mainly along grain boundaries in the microstructure of the service-exposed material, whereas no σ-phase was present in the as-received condition. Laboratory corrosion experiments were carried out using KCl-free and KCl-covered samples in a 15{\%} (v/v) H2O (g) + 5{\%} (v/v) O2 (g) + N2 (g) (balance) atmosphere at 600 °C for 168 h. Microstructural characterisation was performed before and after the corrosion experiments using light optical microscopy, X-ray diffraction spectroscopy, scanning electron microscopy with energy-dispersive X-ray analysis (SEM/EDX) and scanning transmission electron microscopy with energy-dispersive X-ray analysis (STEM/EDX). The presence of KCl resulted in increased attack, and the service-exposed material had increased attack compared to the as-received TP347H FG material; thus, the deepest attack was observed for KCl-covered previously service-exposed material where grain boundary internal attack occurred. The experimental investigations indicate preferential attack of the Cr-rich precipitates and the presence of chlorine at the corrosion front and Cr-rich precipitates (σ-phase) ahead of the corrosion front for KCl-covered service-exposed material. The findings suggest that service-exposed AISI 347H FG material may experience an increased KCl-induced corrosion attack caused by selective attack of the Cr-rich σ-phase.",
author = "Malede, {Yohanes Chekol} and Dahl, {Kristian Vinter} and Melanie Montgomery and Grumsen, {Flemming Bjerg} and John Hald",
year = "2019",
doi = "10.1007/s10853-019-03863-4",
language = "English",
volume = "54",
pages = "13787–13809",
journal = "Journal of Materials Science",
issn = "0022-2461",
publisher = "Springer New York",
number = "21",

}

Effect of service exposure on KCl corrosion attack of AISI 347H FG steel. / Malede, Yohanes Chekol; Dahl, Kristian Vinter; Montgomery, Melanie; Grumsen, Flemming Bjerg; Hald, John.

In: Journal of Materials Science, Vol. 54, No. 21, 2019, p. 13787–13809.

Research output: Contribution to journalJournal articleResearchpeer-review

TY - JOUR

T1 - Effect of service exposure on KCl corrosion attack of AISI 347H FG steel

AU - Malede, Yohanes Chekol

AU - Dahl, Kristian Vinter

AU - Montgomery, Melanie

AU - Grumsen, Flemming Bjerg

AU - Hald, John

PY - 2019

Y1 - 2019

N2 - The effect of ageing of AISI 347H FG austenitic steel on KCl-induced corrosion was investigated by comparing the corrosion attack on tube material previously service-exposed for 100000 h and that on an as-received tube. Cr-rich σ-phase precipitates were found mainly along grain boundaries in the microstructure of the service-exposed material, whereas no σ-phase was present in the as-received condition. Laboratory corrosion experiments were carried out using KCl-free and KCl-covered samples in a 15% (v/v) H2O (g) + 5% (v/v) O2 (g) + N2 (g) (balance) atmosphere at 600 °C for 168 h. Microstructural characterisation was performed before and after the corrosion experiments using light optical microscopy, X-ray diffraction spectroscopy, scanning electron microscopy with energy-dispersive X-ray analysis (SEM/EDX) and scanning transmission electron microscopy with energy-dispersive X-ray analysis (STEM/EDX). The presence of KCl resulted in increased attack, and the service-exposed material had increased attack compared to the as-received TP347H FG material; thus, the deepest attack was observed for KCl-covered previously service-exposed material where grain boundary internal attack occurred. The experimental investigations indicate preferential attack of the Cr-rich precipitates and the presence of chlorine at the corrosion front and Cr-rich precipitates (σ-phase) ahead of the corrosion front for KCl-covered service-exposed material. The findings suggest that service-exposed AISI 347H FG material may experience an increased KCl-induced corrosion attack caused by selective attack of the Cr-rich σ-phase.

AB - The effect of ageing of AISI 347H FG austenitic steel on KCl-induced corrosion was investigated by comparing the corrosion attack on tube material previously service-exposed for 100000 h and that on an as-received tube. Cr-rich σ-phase precipitates were found mainly along grain boundaries in the microstructure of the service-exposed material, whereas no σ-phase was present in the as-received condition. Laboratory corrosion experiments were carried out using KCl-free and KCl-covered samples in a 15% (v/v) H2O (g) + 5% (v/v) O2 (g) + N2 (g) (balance) atmosphere at 600 °C for 168 h. Microstructural characterisation was performed before and after the corrosion experiments using light optical microscopy, X-ray diffraction spectroscopy, scanning electron microscopy with energy-dispersive X-ray analysis (SEM/EDX) and scanning transmission electron microscopy with energy-dispersive X-ray analysis (STEM/EDX). The presence of KCl resulted in increased attack, and the service-exposed material had increased attack compared to the as-received TP347H FG material; thus, the deepest attack was observed for KCl-covered previously service-exposed material where grain boundary internal attack occurred. The experimental investigations indicate preferential attack of the Cr-rich precipitates and the presence of chlorine at the corrosion front and Cr-rich precipitates (σ-phase) ahead of the corrosion front for KCl-covered service-exposed material. The findings suggest that service-exposed AISI 347H FG material may experience an increased KCl-induced corrosion attack caused by selective attack of the Cr-rich σ-phase.

U2 - 10.1007/s10853-019-03863-4

DO - 10.1007/s10853-019-03863-4

M3 - Journal article

VL - 54

SP - 13787

EP - 13809

JO - Journal of Materials Science

JF - Journal of Materials Science

SN - 0022-2461

IS - 21

ER -