The surface depression and temperatures in molten pool with pulsed arc welding

Melting fluids are a key factor during the welding metallurgical process of Ti-6Al-4V that determines the solidification and microstructures of welds. The surface of molten pool is the interface between the arc plasma and fluid, which reflects the effect of arc behavior. The molten surface depression was created by arc force that affects molten fluid. Modeling was established with high frequency pulsed arc welding, and the results were compared with direct current arc welding (DC-AW). The surface tension mechanism was studied at the interface of melting metal and argon, and the results indicated that pulsed arc pressure created large depressions at the same current level. The max depression increased by 60% at 40 kHz compared with DC-AW. The molten pool geometries were calculated with the pre-surface depressions assumption. The melting process, and temperature distribution were compared between DC-&pulsed welding. A large temperature expansion at depth direction was demonstrated and the pulsed arc created large penetration. Large temperature gradient can be found at the edge boundary and low values at the center of molten pool. Furthermore, the temperature gradient approached to zero at the center of molten pool with ultra high frequency pulsed arc welding (UHFP-AW).