Abstract: In order to have a good understanding of the local corrosion behavior of 16Mn steel welded joint by friction stud welding technology, scanning vibrating electrode technique (SVET) and local electrochemical impedance spectroscopy (LEIS) were performed to investigate the corrosion current density and the impedance distribution of the welded 16Mn steel joint along stud, heat affected zone (HAZ), welded zone (WZ), another HAZ and base metal (BM). Metallographic microscope and scanning electron microscope (SEM) were used to observe the microstructure of welded joints. Residual stress in the different zones of the welded sample was measured by an X-ray stress tester. The results show that the weld zone has finer crystalline grains and denser microstructure than other zones. The residual stresses of the welded sample are shown as compressive stress, and the compressive stress in the weld zone is the smallest (-96MPa).The SVET and LEIS data indicate that the weld zone has the lowest current density (0.3霢/cm2) and the largest impedance (169k?), which may be due to the presence of the densest microstructure and the smaller residual stress in the weld zone, and shows the best corrosion resistance.

Key words: friction stud welding, microstructure, residual stress, scanning vibrating electrode technique (SVET), local electrochemical impedance spectroscopy (LEIS)