In Situ Holographic Monitoring of Stress Corrosion Dynamics of Alloy 625 in Cl− + S2O32− Solution

Yang, Pengyu; Gu, Yunzhou; Wu, Fuli; Yuan, Boyu; Li, Liang; Wang, Chao

doi:10.3390/molecules31101716

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In Situ Holographic Monitoring of Stress Corrosion Dynamics of Alloy 625 in Cl⁻ + S₂O₃²⁻ Solution

by

Pengyu Yang

^1,†

,

Yunzhou Gu

^2,†,

Fuli Wu

²,

Boyu Yuan

²,

Liang Li

^1,*

and

Chao Wang

¹

School of Chemistry & Materials Science, Jiangsu Normal University, Xuzhou 221116, China

²

School of Physics and Electronic Engineering, Jiangsu Normal University, Xuzhou 221116, China

^*

Author to whom correspondence should be addressed.

^†

These authors contributed equally to this work.

Molecules 2026, 31(10), 1716; https://doi.org/10.3390/molecules31101716

Submission received: 18 March 2026 / Revised: 5 May 2026 / Accepted: 12 May 2026 / Published: 18 May 2026

(This article belongs to the Special Issue Advancements in Electrochemistry and Corrosion Protection)

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Abstract

This study examined the stress corrosion of Alloy 625 in Cl⁻ + S₂O₃²⁻ solutions using digital holography in combination with electrochemical methods. Without elastic tensile stress, intergranular corrosion (IGC) occurred, due to the higher activity of grain boundaries compared to the grain interior and to preferential adsorption of sulfur (produced by S₂O₃²⁻ decomposition) at these boundaries. Digital holography observations showed that IGC initiated at certain grain boundaries and propagated to adjacent boundaries, even in the absence of elastic tensile deformation. Applying elastic tensile stress (260 MPa, ~46% σy) increased the defect density within the oxide film, thereby enhancing corrosion and anodic currents, and inducing river-like cracks. Although elastic tensile stress suppressed IGC, it simultaneously promoted stress corrosion cracking (SCC), as the stress exerted a stronger accelerating effect on corrosion than the grain-boundary did. Digital holography allowed in situ monitoring of the stress corrosion process in Alloy 625, demonstrating that cracks initiated via localized corrosion/IGC and subsequently propagated along the direction of the applied stress.

Keywords: stress corrosion; digital holography; intergranular corrosion; alloy 625

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MDPI and ACS Style

Yang, P.; Gu, Y.; Wu, F.; Yuan, B.; Li, L.; Wang, C. In Situ Holographic Monitoring of Stress Corrosion Dynamics of Alloy 625 in Cl⁻ + S₂O₃²⁻ Solution. Molecules 2026, 31, 1716. https://doi.org/10.3390/molecules31101716

AMA Style

Yang P, Gu Y, Wu F, Yuan B, Li L, Wang C. In Situ Holographic Monitoring of Stress Corrosion Dynamics of Alloy 625 in Cl⁻ + S₂O₃²⁻ Solution. Molecules. 2026; 31(10):1716. https://doi.org/10.3390/molecules31101716

Chicago/Turabian Style

Yang, Pengyu, Yunzhou Gu, Fuli Wu, Boyu Yuan, Liang Li, and Chao Wang. 2026. "In Situ Holographic Monitoring of Stress Corrosion Dynamics of Alloy 625 in Cl⁻ + S₂O₃²⁻ Solution" Molecules 31, no. 10: 1716. https://doi.org/10.3390/molecules31101716

APA Style

Yang, P., Gu, Y., Wu, F., Yuan, B., Li, L., & Wang, C. (2026). In Situ Holographic Monitoring of Stress Corrosion Dynamics of Alloy 625 in Cl⁻ + S₂O₃²⁻ Solution. Molecules, 31(10), 1716. https://doi.org/10.3390/molecules31101716

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In Situ Holographic Monitoring of Stress Corrosion Dynamics of Alloy 625 in Cl⁻ + S₂O₃²⁻ Solution

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