Local Electrochemical Study of Friction Stitch Welded X65 Steel Using Scanning Vibrating Electrode Technique

Abstract

The corrosion of the friction stitch welded (FStitchW) X65 steel has been studied by local electrochemical techniques, namely scanning vibrating electrode technique (SVET) and local electrochemical impedance spectroscopy (LEIS), under 3.5% NaCl solution. The microstructure of the FStitchW X65 pipeline steel was observed by metallographic microscope and scanning electron microscope (SEM). The hardness of the FStichW samples was tested by a digital microhardness tester. SEM and hardness results showed that the microstructure of the welded zone of the FStitchW sample is compact, the hardness is the maximum. SVET and LEIS results showed that for the welded zone the local corrosion potential is the smallest, and the local impedance is the maximum. What leads to the distinguished corrosion resistance of the welded zone superior to base metal and heat affected area is discussed.