Corrosion Behavior and Microstructural Characterization of Friction Stir Welded API X70 Steel

Friction stir welding (FSW) is an excellent alternative process used in pipelines circumferential welds due to fusion welded joint low corrosion resistance. This study describes the resistance as a function of microstructural features resulting from API X70 FSW joint. The were examined by optical microscopy, scanning electron and x-ray diffraction. analysis was conducted employing potentiodynamic polarization tests using electrochemical microcell, which allowed test small circular areas delimited 2 mm diameter O-ring gasket. base metal heat-affected zone most susceptible regions their banded microstructures. re-stirred-zone resistant associated grain refinement. rate presented approximately six times higher than region least susceptibility corrosion, this case, re-stirred-zone.