Multi-physics coupling simulation of GMAW arc and droplet behaviors based on CFD

A three-dimensional transient model of gas metal arc welding (GMAW) process including the arc plasma and droplet transfer was established to investigate the complex coupling mechanism of mass transfer, heat transfer, electromagnetism, and hydrodynamics. The arc shape, current density, temperature field, electromagnetic force, arc pressure and droplet behavior were analyzed. The results showed that the iron vapor generated on the droplet surface and diffused in the arc, which changed the plasma thermal-pressure distribution. The upward surface tension maintained the forming droplet at the wire tip. The electromagnetic force promoted necking, resulting in a decrease in surface tension. Gravity and plasma drag force accelerated the droplet. The behaviors of the inner arc layer varied periodically with the droplet transfer, while the arc periphery remained stable. Droplet transfer was the result of periodic changes in the resultant of all external forces over time, which also led to periodic changes in arc behavior. This study laid the foundation for further research on the influence of arc and droplet behaviors on the weld pool.

Graphical Abstract