This paper presents a comparison of studies on the local distributed electrical conductivity in stress corrosion crack (SCC) from signals of eddy current testing (ECT) and direct current potential drop (DCPD) aiming to improve SCC sizing accuracy when using electromagnetic non-destructive testing (NDT) methods. Experimental setups of ECT and DCPD were established, respectively, to collect measurement signals due to artificial SCCs in a plate of austenitic stainless steel. The local conductivity in the SCC region was reconstructed from the feature parameters extracted from the measured ECT and DCPD signals through inverse analyses. The inversion strategies for ECT and DCPD, each including an efficient forward simulation and an optimization scheme, were introduced from the viewpoint of conductivity reconstruction. Inversion results obtained from the measured ECT and DCPD signals showed the consistent trend which proved the validity of the predicted electrical conductivity indirectly. It is clarified that the electrical conductivity in a SCC is relatively high at the crack tip area and may become as high as 17% of that of the base material. These results provide a good reference to enhance the sizing accuracy of SCC with an electromagnetic NDT method such as ECT by updating the conductive crack model based on the results of this work. This article is part of the theme issue ‘Advanced electromagnetic non-destructive evaluation and smart monitoring’.

中文翻译：

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用电磁无损检测方法定量评价应力腐蚀裂纹内的电导率

本文比较了涡流检测 (ECT) 和直流电势降 (DCPD) 信号对应力腐蚀裂纹 (SCC) 中局部分布电导率的研究，旨在提高使用电磁无损检测时 SCC 的尺寸精度。 (NDT) 方法。分别建立了 ECT 和 DCPD 的实验装置，以收集奥氏体不锈钢板中人造 SCC 引起的测量信号。SCC 区域的局部电导率是通过逆向分析从测量的 ECT 和 DCPD 信号中提取的特征参数重建的。从电导率重建的角度介绍了ECT和DCPD的反演策略，每个策略都包括有效的正演模拟和优化方案。从实测的ECT和DCPD信号获得的反演结果显示出一致的趋势，间接证明了预测电导率的有效性。已经阐明，SCC 中裂纹尖端区域的电导率相对较高，并且可能高达基材电导率的 17%。这些结果为通过基于这项工作的结果更新导电裂纹模型来提高使用电磁无损检测方法（例如 ECT）的 SCC 的尺寸精度提供了很好的参考。本文是主题问题“高级电磁无损评估与智能监测”的一部分。已经阐明，SCC 中裂纹尖端区域的电导率相对较高，并且可能高达基材电导率的 17%。这些结果为通过基于这项工作的结果更新导电裂纹模型来提高使用电磁无损检测方法（例如 ECT）的 SCC 的尺寸精度提供了很好的参考。本文是主题问题“高级电磁无损评估与智能监测”的一部分。已经阐明，SCC 中裂纹尖端区域的电导率相对较高，并且可能高达基材电导率的 17%。这些结果为通过基于这项工作的结果更新导电裂纹模型来提高使用电磁无损检测方法（例如 ECT）的 SCC 的尺寸精度提供了很好的参考。本文是主题问题“高级电磁无损评估与智能监测”的一部分。