由于非接触式检测的优势，电磁无损检测技术具有实现铁路钢轨裂纹高速在线巡检的可行性，但检测探头与被测钢轨间的快速相对运动引起的速度效应会对巡检结果带来较大影响。从电磁场基本理论出发，对高速漏磁检测中的速度效应进行了分析;依据速度因素的特点提出了钢轨裂纹高速在线电磁巡检的方法，其特征在于采用直流励磁激励的磁轭分别对钢轨踏面进行纵向和横向磁化，检测探头采用布置在磁轭两磁极中间位置的三维霍尔传感器和三维检测线圈以及缠绕在磁轭臂上的检测线圈。在高速无损检测试验平台上的试验结果表明，提出的巡检方法可以有效实现钢轨裂纹的高速在线巡检，且不同方法对不同类型的钢轨裂纹缺陷识别各有优势，方法互补之后可以实现不同类型钢轨以大于200 km/h速度在线巡检及缺陷的有效识别。

For its advantage of non-contact detection, electromagnetic nondestructive testing is feasible to achieve high-speed online rail crack inspection, but the velocity effects caused by the rapid relative motion between the detection probe and the measured rail have a strong impact on inspection results. In this paper, starting from the basic principles of electromagnetic field, the effect of velocity on High-speed Magnetic Flux Leakage Testing was analyzed and some methods of high-speed online rail crack inspection were proposed according to the characteristics of the speed factor. It was concluded that the best test results could be achieved by longitudinally and transversely magnetizing the rail surface with the DC excitation yoke, and the detection probes being with 3D-hall sensors & 3D-coils located in the middle of the yoke magnetic poles and the detection coils being wrapped around the arm of the yoke. The experimental results from the platform of high-speed non-destructive testing showed that the proposed inspection methods could effectively achieve high-speed online rail crack inspection, and different methods had their own respective advantages to identify the different types of rail cracks, methods complementing each other could achieve high-speed online inspection of the different types of rail cracks and effective identification of defects above 200 km/h.