Ultrasonic C-scan detection research for effective connection area of arc-stud-weld joints

Ultrasonic echo signal analysis and C-scan detection are used to investigate arc-stud welds (ASWs). The different connection zones of ASW joints are identified based on the variation of the ultrasonic echo in the time domain and time–frequency domain. The amplitude of the first echo in the time domain is used to differentiate an ASW joint from the base metal. The analysis in the time–frequency domain shows that the fusion and weak connection zones of an ASW joint can be distinguished based on the amplitude at a frequency of 5.6 MHz, and the defects in an ASW joint can be precisely detected based on the amplitude at a frequency of 37.5 MHz. A compound ultrasonic C-scan image based on the amplitudes at these specific frequencies is adopted to intuitively display the actual connection status of an ASW joint. According to this image, the joint diameter and defect dimensions can be quantitatively analyzed. This method provides an effective quality assessment method for an ASW joint.