For studying the difference of corrosion performance of Inconel 625 surfacing layers obtained through hot wire pulse TIG (Tungsten Inert Gas Welding) surfacing, single - layer and double - layer coatings of Inconel 625 were applied on the surface of 20 steel through surfacing. The corrosion performance of surfacing layers with varying number was analyzed by electrochemical test, intergranular corrosion test and EDS component analysis. Results showed that in Bode diagram, the phase angle of double - layer surfacing was 80°, and that of the single - layer surfacing and substrate decreased by 5°and 20° respectively. The slope of impedance modulus and frequency of double - layer surfacing was the largest, followed by single - layer surfacing, and the minimum was the that of substrate. Additionally, the base material had Warbug diffusion and the smallest capacitance arc, while the double - layer surfacing had the largest capacitance arc. Self - corrosion potentials in single - layer and double - layer surfacing were 374.0 mV and 392.0 mV higher than that of the base material respectively, the corrosion current density decreased by about 99.3% and 99.8%, and the double - layer surfacing spot corrosion potential was 430 mV higher than that of the single - layer. After the intergranular corrosion test, no obvious intergranular corrosion appeared in the surfacing layer, but pitting corrosion was observed. Moreover, the weight loss of the double - layer surfacing corrosion was about 1/5 of the single - layer, and the corrosion penetrated along the columnar intergranular. The alloy elements in the fusion zone between layers and the interface with substrate changed significantly and distributed evenly within each layer. The Fe content of double - layer surfacing was lower than that of the single - layer surfacing, and thus the former had a better corrosion resistance.
