摩擦焊接头中的弱结合是一种用常规无损探伤方法无法检测到的缺陷 ,具有很大的危害性。给出了摩擦焊接头超声检测的一种数学模型 ,根据模型发现不同质量的摩擦焊接头其回波信号的幅值—频率特性有明显的区别。对实际接头的检测信号分析也得到了相同的结果。利用超声信号频域分布的先验知识进行小波消噪后 ,可以有效地检测弱结合缺陷的回波信号 Weak bonding in a friction welded joint is a defect that can not be detected by a conventional non-destructive testing method and is very harmful. A mathematical model of ultrasonic testing of friction welding joint is given. According to the model, the amplitude-frequency characteristics of the echo signals of different quality are obviously different. The same result was also obtained from the detection of the actual joint signal. Using the prior knowledge of the frequency domain of the ultrasonic signal to denoise the wavelet, we can effectively detect the echo signal of the weak binding defect