Implementation of a non-intrusive and real-time weld quality monitoring system using spectroscopy

This work describes exploratory experimental procedures implemented for the development of a non-intrusive and real-time sensor for weld defect tracking which uses emission spectrometry for measuring the electromagnetic content of the plasma-weld pool interface in the GMA welding arc. The welding process monitoring is carried out by calculating the Iron (Fe) and the Manganese (Mn) electronic temperatures within the welding arc column, admitting that the observed region is at local thermodynamic equilibrium. The temperature was calculated by utilizing the relative intensity method, which is based on the Boltzmann and the Saba Laws and on the definition of the emission line intensity. The calculated electronic temperatures of the two elements were correlated with the position of welding defects, which have been introduced for simulation purposes. These simulated defects resulted in abrupt changes in the average temperature values, thus providing an indication of the presence of a defect.