针对钢管管端以交流线圈纵向磁化方式探伤时内壁周向缺陷难以检出, 以及以交流电穿棒周向磁化方式探伤时内、外表面磁探灵敏度差异很大等现象, 参照解释交流电磁场集肤效应的方法, 建立了两个定性模型进行推导, 得到结论: 圆筒类工件采用交流线圈纵向磁化时, 磁场主要集中在外表面, 内壁磁场削弱甚至抵消; 采用交流电中心导体法周向磁化时, 磁场集中在内、外表面, 但两处磁场的强度会有不遵循磁探经验公式的较大的差异。此结论能解释试验现象, 有助于对圆筒类工件磁化方法的选择。

Two qualitative models were established by referring to the method to explain skin effect of alternating current magnetic field. Those models could deduce and interpret the phenomena that longitudinal discontinuities defects in the pipe inner surface which were difficult to disclose when longitudinal magnetization using alternating current coils was carried out, and there was a big difference of sensitivity in inner and outer surface when workpieces were magnetized using central conductor through alternating current. Conclusion was drawn that, when alternating current was passing through the coil, magnetic fields in tube-shaped workpieces were mainly collected in outer surface and that in inner surface were weakened or even counteracted. On the other hand, when the workpiece was magnetized by central conductor through alternating current, magnetic fields were in both sides, but the intensity was different, which appeared not to follow empirical formula. This conclusion could explain experiment phenomenon and help to select magnetization methods to detect tube-shaped workpieces.