Plume temperature diagnosis with the continuous spectrum and Wien’s displacement law during high power fiber laser welding.

The laser-induced plume is an essential physical phenomenon during high power fiber laser welding. Its physical nature can be investigated by diagnosing its temperature. In order to overcome the lack of sufficient line spectra in the temperature diagnosis, the continuous spectrum method (based on the continuous spectrum and Wien’s displacement law) is thus developed in this research. The optical spectra emitted by the plume or plasma were detected by using a SP-2500i spectrometer during bead-on-plate welding with an IPG YLS-6000 fiber laser or fiber laser-arc hybrid. The rationality of the continuous spectrum method was evaluated by comparing the plasma temperatures diagnosed by applying the continuous spectrum and line spectra. The results reveal that the continuous spectrum method used in temperature diagnosis is rational. When the line spectra cannot be detected due to an increase in detected height, the plume temperature can be still obtained by using the continuous spectrum method. [ABSTRACT FROM AUTHOR]