针对航空发动机盘环件超声检测中存在的径轴向裂纹取向不利导致检测困难的问题，采用力学加载方式制作含有长度为1.5~10 mm疲劳裂纹的试样，试验对比了纵波直入射缺陷回波法与底波监控法、纵波小角度斜入射缺陷回波法与底波监控法等4种方法对径轴向裂纹的检测能力，并分析了探头参数、裂纹位置等因素对检测能力的影响规律，最后在某涡轮盘上验证了方法的有效性。结果表明，纵波小角度斜入射底波监控法对径轴向裂纹的检测能力最强，使用焦距为89 mm的10 MHz聚焦探头并使声束以2°斜入射时，可检出试样中长为1.5~10 mm的疲劳裂纹，该方法对于接近焦点位置的裂纹检测效果更好。

Aiming at the ultrasonic detection problem caused by unfavorable orientation of radial-axial crack in aero-engine disk and rings, the specimens with fatigue cracks of 1.5-10 mm in length were produced by mechanical loading method. The detection capability of four methods for radial-axial cracks was compared, including defect echo methods and back-wall echo monitoring methods with normal incidence and small angle oblique incidence longitudinal wave, respectively. The influence of probe parameters and crack location on the detection capability was analyzed. Finally, the optimal detection method was verified on a turbine disk. The research reveals that, the back-wall echo monitoring method with a small angle oblique incidence longitudinal wave has the highest detection capability for radial-axial cracks. All fatigue cracks with length of 1.5-10 mm can be detected by using a 10 MHz focusing probe with focal length of 89 mm and oblique incidence angle of 2°. The method is more applicable for cracks that near the focus point.