The effect of adhesive layer on variable polarity plasma arc weld bonding process of magnesium alloy

The effect of adhesive layer was studied during variable polarity plasma arc weld bonding (VP-PAWB) process of magnesium alloy. During the welding process, arc behavior and temperature field on the upper surface of the specimens around arc were observed. In addition, microstructures of the welding joint were analyzed. Variable polarity plasma arc welding (VP-PAW) process was also conducted for comparison. Results revealed that the arc shape was concentrated as a result of the decomposition of the adhesive in alternating current electrode positive (ACEP) stage of VP-PAWB process. In addition, in VP-PAWB, the adhesive replacement of the air layer in VP-PAW made the thermal conductive rate and cooling rate increase. Besides, the adhesive decomposition escape upwards agitated the melt pool. As a result, the grains were refined.