Microstructure and corrosion behavior of the friction stir welded joints made from ultrafine grained aluminum

Joints made from ultrafine grained aluminium alloy 1050 are investigated in order to examine the corrosion behavior and microstructural changes between base materials and stir zones. Samples in the initial state, after four and eight passes of Incremental ECAP (I-ECAP) process were joined with similar plates using Friction Stir Welding. Initially refined microstructure after I-ECAP transformed to homogenous few micron sized grains structure in stir zones. AlFeSi particles present in the microstructure became fragmented during plastic deformation and welding process. The observed minor differences in corrosion resistance include slightly higher values of corrosion potentials but more complex pits' morphology for I-ECAP processed samples comparing to the stir zones.