As one of the fast-developed NDT&E (nondestructive testing and evaluation) techniques, eddy current pulsed thermography (ECPT) is extensively used for crack detection and quantification in ferromagnetic pressure components. However, in the practical inspection, the stress has significant influences on the permeability while that haven’t been concerned. To improve the detection accuracy of crack measurement, this paper focuses on making clear the tensile stress effect on the crack depth quantification in ferromagnetic materials by ECPT. A theoretical analysis, including the ECPT theory, the stress equivalent field theory and the μ-H_σ curve, has been conducted and verified by experiments. The results show that the direction and magnitude of the stress have strong influences on the thermal features. And the tensile stress can increase the linear slope of crack depth quantitative curve. Further, probability of detection (POD) curves prove that the tensile stress enhances the detection capability of shallow cracks by ECPT.

作为快速发展的 NDT&E（无损检测和评估）技术之一，涡流脉冲热成像 (ECPT) 被广泛用于铁磁压力元件的裂纹检测和量化。然而，在实际检验中，应力对渗透率有显着影响，而没有被关注。为提高裂纹测量的检测精度，本文重点阐明拉伸应力对ECPT铁磁材料裂纹深度量化的影响。的理论分析，包括ECPT理论，应力等效场理论和μ - ħ _σ曲线，已经进行并通过实验验证。结果表明，应力的方向和大小对热特性有很大的影响。并且拉应力可以增加裂纹深度定量曲线的线性斜率。此外，检测概率 (POD) 曲线证明拉伸应力增强了 ECPT 对浅裂纹的检测能力。