Pulsed Current Gas Metal Arc Welding under Different Shielding and Pulse Parameters; Part 2: Behaviour of Metal Transfer

The behaviour of metal transfer and arc stiffness understood in terms of arc pressure (P-a) of pulsed current gas metal arc welding (P-GMAW) using mild steel filler wire have been studied with respect to change in pulse parameters under different gas shieldings of Ar+2%CO2 and Ar+18%CO2. The arc environment revealing the droplet transfer from electrode to weld pool in bead on plate weld deposition has been studied by high speed video graphy. Effect of pulse parameters has been considered by their hypothetically proposed summarized influence defined by a dimensionless factor phi, mean current (l(m)) and arc voltage. The droplet diameter and velocity of droplet at the time of detachment are found to vary significantly with the variation of phi. At a given phi the experimentally measured behaviour of metal transfer is found well in agreement to their corresponding theoretical estimates. The average droplet diameter transferred per pulse predominantly reduces but, the velocity of metal transfer at the time of detachment enhances with the increase of phi under both the shielding gases. In general a higher values of phi, l(m) and arc voltage enhances the P-a depending upon type of gas shielding. The use of Ar+2%CO2 shielding gas reduces the droplet diameter and enhances the arc pressure than that observed under Ar+18%CO2 gas shielding.