Research On Welding Detection Of Dissimilar Steel Welding Based On Ultrasonic Phased Array

Dissimilar metal welding technology has been widely used in nuclear safety end,pressure vessel and other fields.The quality of weld seam has an important impact on the safety of the whole structure.The defects in the weld have great influence on its quality.Therefore,it is important to detect defects existing in dissimilar metal welds.Conventional ultrasound is difficult to detect for geometrically complex parts and anisotropic welds because its beam cannot be deflected.Ultrasonic phased arrays are a new type of non-destructive testing method that compensates for the limitations of conventional ultrasonic testing.Compared with conventional ultrasound,it has a big advantage.Based on this,this paper uses ultrasonic phased array technology as a means to study the ultrasonic reflection echo signals of defects by experimentally and theoretically by welding dissimilar metal test plates and prefabricating three different artificial defects,such as pores,inclusions and cracks.Data processing analysis was performed on different types of defect ultrasonic A-scan signals.Research indicates:Ultrasonic phase-controlled detection technology is used to find out that the fan scan images of these three kinds of defects are differentiated according to the detection results.Under the same gain condition,the darker amplitude is higher and easier to be inspected.When detecting inclusion defects,the amplitude of the ultrasonic A sweep is higher,and the amplitude of the pores and cracks is lower.In order to further analyze the defect reflection echo with relevant defect information,the defect ultrasonic Ascan signal is FFT transformed.According to the result,the defect signals are distributed in the low frequency band,and the spectral distribution of different defects has certain differences.Therefore,the wavelet packet transform is performed on the defect signal.According to the wavelet packet transform processing result,it is found that the dB8 wavelet base can better extract the band energy ratio of each defect,which provides a certain basis for defect identification and classification.Ultrasonic phase-controlled detection technology is used to find out that the fan scan images of these three kinds of defects are differentiated according to the detection results.Under the same gain condition,the darker amplitude is higher and easier to be inspected.When detecting inclusion defects,the amplitude of the ultrasonic A sweep is higher,and the amplitude of the pores and cracks is lower.In order to further analyze the defect reflection echo with relevant defect information,the defect ultrasonic Ascan signal is subjected to FFT(Fast Fourier Transform)transformation.According to the result,the defect signals are distributed in the low frequency band,and the spectrum distribution of different defects is A certain difference.Therefore,the wavelet packet transform is performed on the defect signal.According to the wavelet packet transform processing result,the dB8 wavelet base can be used to extract the band energy ratio of each defect,which provides a basis for defect identification and classification.In summary,ultrasonic phased array detection technology can accurately detect dissimilar metal welding defects,and use dB8 wavelet and data mining technology to accurately extract and identify defects.