在漏磁检测中，随着待检测铁磁性构件的厚度的增加和缺陷埋藏深度的增大，缺陷的检出将变得越发困难。为探求漏磁检测的极限探伤能力，在钢板上制作了不同埋藏深度的盲孔，进行了漏磁检测的穿透深度试验，给出了不同磁化程度下的检测信号。在超强度磁化下，实现了埋藏深度为70 mm的 2 mm×20 mm盲孔的检测，对厚壁钢管漏磁探伤的应用具有指导价值。

In MFL inspection, as the thickness of the ferromagnetic material to be detected or the buried depth increases, flaws are more and more difficult to be found. In order to search the ultimate, the detectability was studied experimentally on a thick steel plate with blind holes in different depth. Signals under different magnetizations were given. High SNR MFL signal was realized in the test of  2 mm×20 mm blind holes whose depth was up to 70 mm on condition that the magnetization was approaching to saturation，which could provide guidance for thick wall steel tube .