Enhanced melt pool stirring in welding with dynamic polarised laser beam

Abstract

The stirring of the molten material during CO 2 laser welding with a dynamic polarised laser beam (DP) was studied. The key element of the set-up is a high power interference laser beam modulator for CW power rating up to 4 kW. Metallographic cross-sections and EDX analyses of the realised welds in St37 using the contrast material nickel proved the enhancement of melt pool stirring due to DP. Moreover, roughness measurements confirmed a smoothing of the top bead surface as well as a correlation between melt pool stirring and the formation of the top bead ripple structure.

Vibration assisted welding processes and their influence on quality of welds

“…Workpieces were clamped on a table vibrating longitudinally with the help of an electrodynamic vibrator and welded using manual metal arc welding. Rutile coated mild steel electrodes were used, and the welding current, voltage, energy input, arc length a vibration of workpiece; 15,16,44,[46][47][48][49][50][51][52][53][54][55] b weld pool oscillation; [56][57][58][59]61,[63][64][65][66][67][68][69][70][71][72][73][74][75] c molten droplet oscillation using pulsed current; [76][77][78][79] d oscillation of welding arc; [80][81][82][83][84][85][86][87][88][89][90][91][92] e vibration of electrode…”

“…Stirring of molten metal during CO 2 laser welding with dynamic polarised laser beam resulted in smooth top bead surface. 57 The workpiece was made of steel St37 with nickel foils placed between steel sheets as contrast material. The contrast material helped for appropriate visualisation of molten pool stirring.…”