Abstract: Different ultrasonic properties of residual stress and deformated microstructure of the friction welded – joint are studied through the experiments in which the welded – joint are tested in an ultrasonic immersion transmission way. The results show that residual stress cause the low frequency component of the ultrasound attenuate apparently and mainly affect the magnitude on the harmonic coefficient, while deformated microstructure have influence mainly on the high frequency component of the ultrasound and the law of the harmonic coefficient.

Key words: Deformated microstructure, Residual stress, Ultrasonic properties