Effect of Rare Earth Metals Added to Wire on Droplet Transfer Mode in GMAW with Pure CO2 Shielding Gas

Abstract

The effect of rare earth metals added to wire on droplet transfer mode in GMAW with pure CO2 shielding gas was reviewed. The results show that when the welding wire containing rare earth metals is welded with DCEN pure CO2 shielding gas, owing to the expansion of the cathode spot area in the arc (the arc above the droplet presents a conical shape), the refined droplets form an axial spray transfer mode, the spatter generation is very small, and the usability is excellent. The rare earth metals reduce the work function of the cathode electrons, at the same time, the high electromagnetic pinch force allows the droplets to transition axially in a smaller size, and the direction of the dominant force acting on the droplets facilitates the droplet transfer, and finally the formation conditions of droplet spray transfer are fully satisfied under pure CO2 shielding gas. The application of welding wire containing rare earth metal in new power supply with current waveform control makes the J-STAR® welding method realize ultra-low spatter in a wide current range, which widens the application range of the process.

Keywords

• rare earth metal
• droplet transer mode
• gmaw with pure co2 shielding gas
• cathode spot
• axial transfer