中文摘要：

提出一种直流漏磁和涡流复合探伤方法，以期通过信息融合提高检测灵敏度，但试验中发现涡流探头检测到了钢管的内壁裂纹，而钢管的涡流检测规范也认为信号由涡流效应引起的。采用有限元法和磁源的测试试验分析磁导率和漏磁场对涡流检测信号的影响，结果表明，认为检测信号为涡流效应引起的观点是有误的。应用等效源法对扰动磁场进行分析，理论分析表明，裂纹处由涡流效应引起的扰动磁场相比漏磁效应引起的漏磁场要小得多，裂纹的漏磁场导致检测线圈产生感应电动势从而获得检测信号，而此时涡流效应引起的信号被淹没在漏磁信号巾，钢管在磁饱和状态下的涡流检测信号是由裂纹的漏磁场引起的，饱和磁化下铁磁性构件的涡流检测结果要重新认识。

英文摘要：

In order to improve sensitivity through information fusion technology, a combined DC magnetic flux leakage and eddy current testing method is proposed. Experimental results indicate that the inner wall cracks in the steel pipe are detected by eddy current system. In fact, the dilemma between the experimental signal and skin effect principle is obviously. Two factors including permeability and magnetic flux leakage that have influence on eddy current signal are analyzed with finite element method and verification experiments of magnetic source. So the viewpoint, that the signal of the internal crack is caused by eddy current effect may be erroneous. Perturbed magnetic field is analyzed by using equivalent source method. Theoretical analysis shows that magnetic flux leakage produced by the crack is far stronger than perturbed magnetic field induced by eddy current effect. The induced electromotive force is created by the variation of the magnetic flux within the cross section of the pick-up coil when the probe moves along the steel pipe with a crack. The signal produced by eddy current effect is submerged. Therefore, the signal of eddy current probe is induced by magnetic flux leakage produced by the crack. Eddy current testing results of ferromagnetic materials under saturation magnetization should be reinterpreted.