Characterization of Metal Dusting Corrosion of Ni-Based Alloy Ni29Cr2Al and Its Weldment Under High Pressure Condition

W.-T. Chen, B. Li, B. Gleeson, M.C. Galetz, H. Hattendorf

in "Proceedings of Corrosion 2019" (2019), NACE

Metal dusting can be a severe failure mechanism of metallic materials exposed to industrial process environments containing high carbon activity. There have been many studies on the metal dusting behaviors of alloys in 1 atm environments, but some recent laboratory-scale studies have shown that typically-resistant alloys are apt to undergo more severe metal dusting attack under high-pressure conditions. The current study analyzes the metal-dusting behavior of a Ni-based Ni29Cr2Al alloy weldment tested under 19 bar total pressure at 620 °C. Of particular interest is the mechanism by which a higher pressure favors the initiation of dusting attack. It will be shown that regions of the heat-affected zone (HAZ) and weld surfaces were much more prone to dusting attack than the as-processed wrought alloy surface. However, regions of the weldment which formed fine grains at the surface could exhibit excellent resistance to metal dusting. The effects of such microstructural factors on oxidation resistance were directly related to conferring dusting resistance.

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