Influences of pulsed current parameters on mechanical and metallurgical properties of gas tungsten arc welded AZ31B magnesium alloy

This paper reveals the influences of pulsed current parameters, namely peak current, base current, pulse frequency and pulse-on time, on the mechanical and metallurgical properties of gas tungsten arc welded AZ31B magnesium alloys. Twenty joints were fabricated using different levels of peak current, base current, pulse frequency and pulse-on time. The tensile properties of the welded joints were evaluated and correlated with the weld zone’s microstructure and hardness. Optical microscopy, scanning electron microscopy and X-ray diffraction were used to evaluate the metallurgical characteristics of the welded joints. The joints fabricated using a peak current of 210 A, base current of 80 A, pulse frequency of 6 Hz and pulse on time of 50 % yielded tensile properties superior to the other joints. The formation of fine grains in the weld region, higher fusion zone hardness and uniformly distributed precipitates are the main reasons for the superior tensile properties of these joints.