Experimental investigation of weld pool formation in electron beam welding

Abstract The energy transfer mechanism from an electron beam to a metal target, weld pool and keyhole of formation during electron beam welding was studied using a collector for secondary emitted particles, light photo diodes and CCD techniques. The physical processes in the welding pool and plasma cavity are discussed. It is shown that the nature of the heat source in a weld pool is non-stationary and the dynamic processes occurring in both the welding pool and the plasma cavity play a dominant role in the formation of the welding seam during electron beam welding of metals. Periodical molten metal flows were determined at low oscillation frequencies of the welding seams root for frequency between 0.5 and 50 Hz and on the surface of the welding pool in the interval 5–850 Hz. The frequency spectrum of the secondary electron emission signal is in the order of a few kHz.