Bobbin and conventional friction stir welding of thick extruded AA6005-T6 profiles

Conventional and bobbin friction stir welding processes (FSW and BFSW, respectively) were employed for joining 10 mm thick extruded AA6005-T6 profiles. The FSW and BFSW techniques were employed using two sets of parameters resulting in slow and fast processes. In general, the bobbin tool enabled welding with faster welding speeds than the conventional FSW technique. A comprehensive in-situ thermal analysis was performed using thermocouples. It was evident that, in a like-for-like comparison, i.e., employing the same set of welding parameters, the BFSW technique introduces a somewhat higher peak temperature, however, lower heat input and, more importantly, a higher cooling rate than the conventional FSW. Accordingly, a somewhat finer microstructure was formed in the stir zone of the BFSW samples than in the FSW ones, resulting in higher hardness values, and slightly higher ultimate strengths in the BFSW samples. (C) 2016 Elsevier Ltd. All rights reserved.