Modeling of the transport phenomena in GMAW using argon–helium mixtures. Part II – The metal

In this Part II, the effects of shielding gas compositions on transport phenomena in the metal are reported which include the transient processes of electrode melting; droplet formation, detachment, transfer and impingement onto the workpiece; weld pool dynamics and weld bead formation. It was found from the present study that electromagnetic force, which is affected by shielding gas compositions, plays the most significant role in determining the behaviors of metal transfer. For the same welding power input, the increase of helium content in the mixture leads to the formation of larger droplets and the decrease of droplet detachment frequency. The predicted phenomena on metal transfer are consistent with the reported experimental observations. Detailed discussions about the reasons causing the very interesting and unusual transport phenomena in the metal are given.