Feasibility study of using magnetic and thermoelectric methods for the assessment of storage-induced changes in flux-cored welding wires

Abstract

The lack of knowledge regarding whether a welding consumable remains suitable for the welding process or has undergone degradation that precludes its further use constitutes a significant challenge. Appropriate control procedures and effective evaluation methods may contribute to addressing this issue. This study presents the results of investigations concerning the applicability of magnetic and thermoelectric methods for such an assessment. Rutile flux-cored welding wires were stored in four different locations and subsequently collected for testing after 3, 6, and 12 months. Their suitability for industrial application was initially assessed on the basis of visual examination. Subsequently, measurements of thermoelectric power, characterization of bulk magnetic properties, and Magnetic Barkhausen Noise (MBN) were performed for each wire. Visual inspection confirmed the good surface condition of the wires despite the exceedance of the recommended limits of temperature and relative humidity during storage. The thermoelectric measurements showed that storage environment significantly affects the Seebeck Coefficient (SC) of welding wires, with marine conditions inducing rapid changes and less aggressive environments producing a gradual time dependent increase. Magnetic property measurements indicated that two of the evaluated parameters, namely the amplitude of MBN and the area under the envelopes of MBN, exhibited changes with storage time at each exposure site. Statistical analysis demonstrated that the parameters recorded during magnetic and thermoelectric measurements were characterized by a high degree of correlation, exceeding 0.9 in some cases. A strong linear relationship between the MBN Amplitude-to-Envelope Ratio and SC was observed for wires stored in the Urban Area and Workshop environments (r = 0.99 for both), indicating a close correlation between the evolution of their thermoelectric and magnetic properties during storage. This finding indicates the potential applicability of these methods for the detection of changes occurring in flux-cored wires during storage.