用涡流放置式探头探伤时 ,可把工件看成半无限大平面 ,用电磁场理论推导出特征频率的计算公式 ,按最大灵敏度原则计算出材料的工作频率选择范围。通过实验 ,给出了常用材料的表面裂纹在一定频率下的检测结果 When eddy current probe is used for flaw detection, the workpiece can be regarded as a semi-infinite plane. The calculation formula of the characteristic frequency can be derived from the theory of electromagnetic field and the range of working frequency selection can be calculated according to the principle of maximum sensitivity. Through experiments, the test results of the surface cracks of common materials at a certain frequency are given