ULTRASONIC TESTING FOR FRICTION WELDED-JOINTS IN LOW-CARBON STEEL WITH WEAK BONDING

In this paper, ultrasonic non-destructive testing to detect weak bondi ng of friction-welded joints is discussed. A modern spectrum analysis using autoregressive (AR) power spectra is used to recognise the vario us defects causing weak bonding, such as lack of fusion and grey speck . The defects discussed in this paper are very difficult to detect usi ng conventional ultrasonic testing methods on friction-welded joints. The results show that the weak bonding defects cannot be detected in t he time domain. Characteristics obtained from the frequency domain of the AR power spectrum, however are useful to detect the various weak b onding defects, and the area of the defects can be indicated by a char acteristic value obtained from the frequency spectrum.