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3722867 
Journal Article 
CHARACTERIZATION OF COLD LAP DEFECTS IN TANDEM ARC MAG WELDING 
Li, P; Svensson, LE; Nylen, P; Markocsan, N; Klement, U 
2012 
1 
Welding in the World
ISSN: 0043-2288 
56 
9-10 
20-25 
WOS:000309080800003 
The objective of this investigation was to classify and characterize the small lack of fusion defects, called cold lap, located at the weld toe. Since the defects are very small (0.01-1.5 mm) and difficult to detect by NDT methods, a better understanding of the formation mechanism is required to be able to avoid their formation. The investigation consisted of two parts. Firstly, a study was made on the type and frequency of cold laps. Three types were identified, namely "spatter cold lap", and "overlap cold lap" and "spatter-overlap cold lap". No relation between type or frequency of cold laps and the welding parameters could be established. Secondly, the interface between spatter and the base material was investigated using optical and scanning electron microscopy, to better understand the cold lap formation mechanism. Manganese-silicate particles were found in the interface located in such a way that they may assist cold lap formation. 
Arc welding; MAG welding; Tandem welding; Oxides; Lack of fusion; Wire feed; Speed; Voltage; Process parameters; Spatter