Eddy current array testing (ECAT) is a useful tool in evaluating defect sizes. However, it is difficult for ECAT to evaluate the inner defects in ferromagnetic materials due to thin skin effect. In this article, direct current (dc) magnetization-based ECAT (DCMECAT) is proposed to quantify buried defects existing in the inner surface of steel plates. Relying on permeability disturbance in the defect vicinity, DCMECAT can build links between the testing signals and defect sizes. The results show that the performance of evaluating defect sizes is better under the saturated magnetization state. Further, three features, i.e., the signal width, the peak voltage, and the contour orientation, are proposed to evaluate the width, the depth, and the orientation of defects, respectively. Relationships between features and defect sizes are investigated by using least-squares regression. Further, a testing example is shown in this article, and the evaluation error is 14%.

中文翻译：

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使用基于直流磁化的涡流阵列测试定量评估铁磁钢中的埋藏缺陷

涡流阵列测试 (ECAT) 是评估缺陷大小的有用工具。然而，由于薄皮效应，ECAT 很难评估铁磁材料的内部缺陷。在本文中，提出了基于直流 (dc) 磁化的 ECAT (DCMECAT) 来量化钢板内表面存在的埋藏缺陷。依靠缺陷附近的渗透率扰动，DCMECAT 可以在测试信号和缺陷尺寸之间建立联系。结果表明，饱和磁化状态下评价缺陷尺寸的性能较好。此外，提出了三个特征，即信号宽度、峰值电压和轮廓取向，分别用于评估缺陷的宽度、深度和取向。通过使用最小二乘回归来研究特征和缺陷尺寸之间的关系。此外，本文给出了一个测试示例，评估误差为14%。