Campus Units

Aerospace Engineering, Chemical and Biological Engineering, Materials Science and Engineering, Mechanical Engineering

Document Type

Article

Publication Version

Accepted Manuscript

Publication Date

7-30-2018

Journal or Book Title

Electrochimica Acta

DOI

10.1016/j.electacta.2018.07.207

Abstract

Pipeline steels are vulnerable to stress corrosion cracking (SCC) during intergranular corrosion (IGC) at potentials of active dissolution in moderately alkaline carbonate-bicarbonate solutions. Morphology evolution accompanying IGC has not been fully described, despite the relevance of the corrosion geometry to crack initiation. The present article reports a characterization of concurrent morphology and mechanical stress development during the initial stages of IGC of X70 steel in sodium bicarbonate solution, in the potential range of high SCC susceptibility. Morphology was revealed by scanning electron microscope examination of cross sections through the IGC layer, and stress evolution was monitored by curvature interferometry. At potentials in the range of SCC susceptibility, IGC creates triangular wedges of porous corrosion product centered at grain boundary triple junctions. The wedge shape indicates a higher corrosion rate at the grain boundary compared to the grain surfaces. Compressive stress is generated during IGC due to internal oxidation on grain surfaces forming a thin compact corrosion product layer. Polarization at a potential below the SCC range resulted in selective grain dissolution with no internal corrosion product or compressive stress increase. Silicon solute atoms are selectively oxidized into the compact grain boundary corrosion product film.

Comments

This is a manuscript of an article published as Yavas, Denizhan, Abdullah Alshehri, Pratyush Mishra, Pranav Shrotriya, Ashraf F. Bastawros, and Kurt R. Hebert. "Morphology and stress evolution during the initial stages of intergranular corrosion of X70 steel." Electrochimica Acta (2018). DOI: 10.1016/j.electacta.2018.07.207. Posted with permission.

Creative Commons License

Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.

Copyright Owner

Elsevier Ltd.

Language

en

File Format

application/pdf

Available for download on Tuesday, July 30, 2019

Published Version

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