Effect of the weld thermal cycles of the modified indirect electric arc on the mechanical properties of the AA6061-T6 alloy

Results of temperature measurements during welding of 12.7mm thick AA6061-T6 alloy plates by modified indirect electric arc (MIEA) are presented. This study describes the thermal cycles in the heat-affected zone (HAZ) and also in the fusion zone. Depending upon the position of the transducers, the maximum temperatures measured in the HAZ ranged from 308 to 693°C, these measurements were related with the tensile test results and the failure zone reported previously by the authors (Ambriz et al., S&I 2006;11:10-17). It was observed that there is a decrease in the mechanical strength of the welded joints, due to the microstructural changes undergone by the AA6061-T6 alloy in which formation of the b0 occurs according to the time-temperature transformation diagram. The inherent cooling conditions of the weld pool observed for the MIEA technique (single welding pass) have made it possible to establish the characteristics of solidification and microstructure for a specific cooling rate.