Abstract: The radiation of laser-MAG hybrid welding plasma is collected with fiber spectrometer. The spatial distribution of spectra from 200 to 1 100 nm is studied and spectral bands are selected. The selected spectral bands include ultraviolet radiation (Fe II dominated), visible radiation (Fe I dominated) and infrared radiation (Ar I dominated). The radiation in the selected spectral bands is acquired to compare the radiation intensity of different scanning surface. Furthermore, high speed video is also applied to studying the coupling of laser-MAG hybrid welding plasma. The result shows that there is a high radiation intensity zone with great gradient in the center of laser hybrid welding plasma. The spectral bands of FeI and FeII have a broader radiation range for laser-MAG welding. This is significant near the laser focusing position. The radiation increases in the middle and lower part of the plasma, especially near the welding pool. However, it decreases in the upper part of welding plasma. The welding process with laser hybrid will cause the plasma energy to focus on the center of welding arc and the welding pool. The broader radiation range of Fe ion provides ionizing duct for welding arc, thus makes the welding arc stable. The coupling effect provides better bead formation and more stable arc in the laser-MAG hybrid welding process.

Key words: Hybrid welding, Laser, Plasma, Spectrum