Corrosion degradation of Inconel 601 in a static lead melt at temperatures of 450 and 650 °C

Abstract

The results of the study of corrosion degradation of the INCONEL 601 alloy in a static lead melt with limited oxygen access at temperatures of 450 and 650 °C for 1440 hours, with intermediate examination of samples after 240, 480 and 1000 hours of testing, are presented. It was found that increasing the melt temperature from 450 °C to 650 °C leads to an increase in the corrosion rate of the alloy by more than 10 times. On the other hand, an increase in the duration of the tests is characterized by a tendency to reduce the corrosion rate by approximately 2 times at a melt temperature of 650 °C and by more than 11 times at a melt temperature of 450 °C, which is explained by the formation of surface-blocking protective oxide films and corrosion products. The steel surface morphology of the formed oxide deposits, the structure and elemental composition were studied by X-ray spectral microanalysis with an energy dispersive spectrometer. The results of optical microscopy and durometric analysis are also presented. It was also found that after the tests, a layer of corrosion products of a dense sandwich structure is formed with a clear separation of layers, which include O, Al, Cr, Fe, Ni and Pb, and the quantitative composition of which varies with thickness. It is shown that molten lead, after 1440 hours, replaces nickel in the surface layers of the alloy, penetrating deep into the base metal, and nickel, due to diffusion through the melt, crystallizes on the surface of the melt in the form of nickel oxide.