Investigation of porosity in pulsed GTAW of aluminum alloys based on spectral and X-ray image analyses

Abstract Alternating current pulsed gas tungsten arc welding was conducted to study the effect of welding conditions on the formation of porosity. Two conditions involved in the preparation of base metals were discussed: the application of a groove and thickness of the welding root face. Spectral analyses based on data mining and empirical mode decomposition (EMD) were proposed to detect porosity. Spectral lines were identified accurately by data mining based on an improved K-medoids algorithm which ascertained the classification number using a geodesic minimum spanning tree. EMD was employed to eliminate effectively the influence of noise and a pulsed current on spectral intensity ratio, resulting in clear characteristic values used for detection of pores. X-ray analyses verified the proposed method and showed that the welding conditions significantly affected the size and distribution of pores. The results indicated that the weld quality was improved with the application of a groove. And the number of pores and pores area decreased significantly when the thickness of the welding root face was 2 mm.

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