EBSD Technique Visualization of Material Flow in Aluminum to Steel Friction-Stir Dissimilar Welding

The material flow characteristics of butt-joints between AA6181-T4 Al alloy and high strength DP600 steel was investigated. The investigations involved analyses by scanning electron microscopy (SEM) combined with electron back-scattered diffraction (EBSD). EBSD is a SEM add-on package that allows local crystallographic analysis of crystalline microstructure. AA6181-T4 Al alloy and DP600 steel sheets were friction stir welded in butt-joint configuration using a gantry system equipped with a mechanical clamping table. The samples to be analyzed were submitted to standard metallographic preparation procedures and etched in a 5% Nital solution in order to allow the visualization of grain boundaries in the DP600 steel microstructure. The results showed that the plastic deformation, material flow and mechanical mixing exhibited distinct asymmetric features in both sides of the weld. The upper part of the DP600 steel with material flow resulted the deformation and forging, where EBSD proved to be a powerful applied tool for material flow visualization.