钢管涡流探伤中，为克服铁磁性金属磁导率对探伤的影响，需要对钢管进行饱和磁化。在实际检测中有时会出现缺陷信号的相位无法分辨的问题。理论分析及试验表明，磁化导致存在涡流效应以及漏磁效应两种机理。当磁化强度过饱和时，漏磁效应强于涡流效应，由于缺陷的漏磁信号不含有相位信息，使得缺陷信号相位无法分辨；当磁化强度合适时，涡流效应占主导地位，这时检测结果阻抗平面图上的各缺陷信号的形式与非铁磁性涡流探伤结果类似，缺陷相位分辨清楚。

In the eddy current testing for steel tubes, the saturated magnetization was needed in order to reduce the effect of the magnetic permeability uncertainly. There was a problem that the phases of defect signals could not be distinguished sometimes. Theoretical analysis and experimental results showed that there were two effects, eddy current effect and magnetic flux leakage effect in this situation. When the magnetization intensity of the tubes was oversaturated, the magnetic flux leakage effect was dominant. As the signals from magnetic flux leakage effect were not related to the phase, there was no way to distinguish defects through their phase difference. On the other hand, when the magnetization was proper, the phase difference of the signal for different defects was very clear. It was the same that the appearance of testing signals in the impedance chart as the one for non-ferromagnetic materials.