Corrosion-Fatigue fracture mechanisms in Q690qNH Steel: Dislocation mediated crack tip dissolution

IF 5.3 2区工程技术 Q1 MECHANICS

Engineering Fracture Mechanics Pub Date : 2025-10-16 DOI:10.1016/j.engfracmech.2025.111630

Yaohan Du , Siyuan Li , Zhendong Li , Xuefeng Xiao , Xue Li , Yongjie Liu , Chao He , Ying Yang , Kun Yang , Qingyuan Wang

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引用次数: 0

Abstract

Corrosion-fatigue fracture mechanisms in Q690qNH high-strength bridge steel were investigated via fatigue testing in 3.5% NaCl solution. Multi-scale characterization revealed an 89% reduction in fatigue strength at 10 million cycles due to corrosion-induced elimination of the conventional fatigue limit. Crucially, high-resolution transmission electron microscopy (HRTEM) first identified β-FeOOH as the initial corrosion product at dislocation interfaces, proving sustained electrochemical activity at crack tips. Heterogeneous plastic deformation reduced electron work function and corrosion potential, maintaining high electrochemical activity that prevented passivation and enabled anodic dissolution-dominated crack propagation. Consequently, prior austenite grain boundaries (PAGBs) and high-angle grain boundaries (HAGBs) lost their barrier function via strain-localized dissolution. This work establishes a dislocation-mediated stress-corrosion coupling mechanism that governing marine bridge steel degradation, advancing marine bridge fatigue failure prediction.

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Q690qNH钢的腐蚀疲劳断裂机制：位错介导的裂纹尖端溶解

通过3.5% NaCl溶液的疲劳试验，研究了Q690qNH高强桥钢的腐蚀疲劳断裂机理。多尺度表征表明，在1000万次循环中，由于腐蚀导致常规疲劳极限的消除，疲劳强度降低了89%。关键是，高分辨率透射电子显微镜（HRTEM）首次发现β-FeOOH是位错界面处的初始腐蚀产物，证明了裂纹尖端处持续的电化学活性。非均质塑性变形降低了电子功函数和腐蚀电位，保持了较高的电化学活性，防止了钝化，使阳极溶解主导的裂纹扩展成为可能。因此，先前的奥氏体晶界（pagb）和高角度晶界（HAGBs）通过应变局域溶出失去了屏障功能。建立了位错介导的控制海洋桥梁钢材退化的应力-腐蚀耦合机制，为海洋桥梁疲劳破坏预测提供了理论依据。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Engineering Fracture Mechanics 物理-力学

CiteScore

8.70

自引率

13.00%

发文量

606

审稿时长

74 days

期刊介绍： EFM covers a broad range of topics in fracture mechanics to be of interest and use to both researchers and practitioners. Contributions are welcome which address the fracture behavior of conventional engineering material systems as well as newly emerging material systems. Contributions on developments in the areas of mechanics and materials science strongly related to fracture mechanics are also welcome. Papers on fatigue are welcome if they treat the fatigue process using the methods of fracture mechanics.