Pitting behavior of austenitic stainless-steel welded joints with dense inclusions and methods to enhance pitting resistance
Anti-Corrosion Methods and Materials
ISSN: 0003-5599
Article publication date: 8 August 2024
Issue publication date: 30 October 2024
Abstract
Purpose
This study aims to assess the pitting resistance of austenitic stainless steel welded joints fusion zone (FZ) with high density of inclusions before and after surface treatment, including potentiostatic pulse technique (PPT) and pickling.
Design/methodology/approach
The potentiodynamic polarization tests and critical pitting temperature tests were carried out for estimating pitting resistance. The PPT and pickling were performed as surface treatment. Scanning electron microscope (SEM) and energy dispersive spectrometer were used for characterize the microstructure and elemental distribution. Electron back-scattered diffraction (EBSD) was used to assess the portion of phases and morphology of grains.
Findings
The weld metal exhibits a higher degree of alloying compared to the base metal, and it contains d-phase and sulfur-containing inclusions. Sulfur-containing inclusions serve as initiation sites for pitting, and they diminish the pitting resistance of weld metal. Both PPT and pickling can remove sulfur-containing inclusions, but PPT causes localized dissolution of the weld metal matrix around the inclusions, while pickling does not. Because of the high density of inclusions, certain pits initiated by PPT are significantly deeper, which makes the formation of stable pitting easier. Because of the high density of inclusions, certain pits initiated by the PPT are deeper. This characteristic facilitates the progression of these initial defects into fully developed, stable pits.
Originality/value
Analysis of pitting initiation in shielded metal arc welding FZ with PPT and ex situ SEM tracking observation. Explanation of why the PPT surface treatment is not able to enhance the pitting resistance of stainless steel with a high inclusion density.
Keywords
Acknowledgements
This work is funded by the National Natural Science Foundation of China (grant No. 52271053 and 52071082).
Ethical compliance: All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.
Citation
Zhou, Q., Sun, Y., Wang, X., Tan, X., Jiang, Y. and Li, J. (2024), "Pitting behavior of austenitic stainless-steel welded joints with dense inclusions and methods to enhance pitting resistance", Anti-Corrosion Methods and Materials, Vol. 71 No. 6, pp. 764-777. https://doi.org/10.1108/ACMM-06-2024-3040
Publisher
:Emerald Publishing Limited
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