针对石油双层复合金属管的非破坏性原位鉴别问题，提出了一种基于脉冲涡流的复合金属层材料鉴别方法。该方法充分利用脉冲涡流频谱范围广、检测深度大的优势，采用脉冲涡流检测方法避免了包覆金属层的屏蔽效应，实现了对待测金属层的检测与识别。对不锈钢包覆的铜、铁、铝等3种模拟试样开展脉冲涡流检测试验，提取了信号主峰幅值、主峰面积、过零时间及衰减时间等4个特征并进行分析。结果表明：上述4个特征都可以将铁磁性材料（铁）和非铁磁性材料（铜、铝）进行有效区分，过零时间则可以进一步实现对铜和铝材料的区分。上述研究证实了脉冲涡流检测在复合金属层材料鉴别中的有效性，为石油双层复合金属管的检测提供了借鉴。

Aiming at the problem of nondestructive in-situ identification of double clad metal tube in oil industry, a method based on pulsed eddy current for composite metal layer materials identification is proposed. The method takes advantages of pulsed eddy current, such as its wide frequency band and large detection depth, to realize the detection and identification of cladding metal layer by eliminating its shielding effect. In the experiment, pulse eddy current signals of three specimens of copper, iron, and aluminum cladded by stainless steel were acquisited and four characteristics of peak amplitude, peak area, zero-crossing time and decay time were extracted. The result shows that the four characteristics can effectively distinguish magnetic materials (iron) from non-ferromagnetic materials (copper, aluminum), and zero-crossing time can further realize the distinction between copper and aluminum. This research demonstrates that pulsed eddy current is effective for the material identification of composite metal layers, it provides reference for the in-situ identification of double clad metal tube.