فهرست نشریات علمی دسترسی آزاد ایران

The purpose of this study is to examine the corrosion resistance of the Nimonic 80 superalloy welded with 625 filler metal using continuous and pulse welding strategies after cold working. The experiments using these strategies were divided into four cases with different cold work levels. Two specimens were welded using the continuous method, while two were welded with pulse welding. Cold pre-working (rolling) was applied to the specimens: 25 and 50% cold rolling for the continuous welded specimens, and 50% cold work for the pulse-welded ones. Welding conditions included a constant current of 100 A and 12 V for the continuous method, while pulse welding used variable currents with peak/base combinations of Ip = 150 A / Ib = 50 A and Ip = 125 A / Ib = 75 A. X-ray diffraction (XRD) analysis identified phases like nickel, molybdenum, and titanium in the specimens. They were then tested in a 3.5 wt.% NaCl solution using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). Results showed that specimens welded with both methods, including 25% cold work in the continuous welds and 50% cold work in pulse welds at 150/50 A, had the highest corrosion potential and the lowest corrosion current density. Cold working enhanced the thermodynamic and kinetic aspects of corrosion resistance, though its overall effect on the corrosion rate was minor. Impedance tests indicated that the specimens with 25% cold work welded with the continuous method and those with 50% cold work welded by pulse welding at 150/50 A had the highest polarization resistance and the lowest charge accumulation. Conversely, specimens with 50% cold work welded by the continuous method and pulse welding at 125/75 A showed the lowest charge transfer resistance and the highest capacitive behavior.