Refill friction stir spot welded AA5754-H22/Ti-6Al-4V joints: Microstructural characterization and electrochemical corrosion behavior of aluminum surfaces

The present study assessed the influence of refill friction stir spot welding (RFSSW) process on the microstructure and electrochemical corrosion behavior of the AA5754-H22 alloy surface of an AA5754-H22/Ti-6Al-4 V overlapped joint. The results demonstrate that the RFSSW process promotes substantial microstrutural changes along the welded joint, which, in turn, reflect directly on the mechanical properties and corrosion behavior of distinct welding regions. The potentiodynamic polarization tests and electrochemical impedance spectroscopy measurements indicate that the stir zone region has better corrosion resistance than the other RFSS welded regions [heat affected zone and base metal] due to higher homogeneity and microstructure refinement. The achieved results are evidence that the RFSSW process is an interesting alternative for the welding of overlapping dissimilar joints.