Effect of pulse current on microstructure and mechanical properties of variable polarity arc weld bead of 2219-T6 aluminium alloy

Abstract

Pulse current variable polarity arc welding of 2219-T6 aluminium alloy was carried out at different frequencies. The effects of pulse current on the microstructure and mechanical properties of the joints were also investigated. Experimental results show that pulse current contributes to not only degree of grain coarsening, but also the distribution of the second phase particles. The tensile strength of joints increases with increasing frequency of the pulse current when the frequency is <10 kHz. The maximum tensile strength can reach 67% of that of the base material without any post-weld heat treatment at the pulse frequency of 10 kHz. When the frequency is >10 kHz the tensile strength decreases with increasing pulse frequency.