Metal Dusting Corrosion of Nickel-Based Alloys

Abstract

Metal dusting corrosion of nickel-based alloys (i.e. Inconel 600, 601 and 693) has been simulated in high carbon activity environments over a temperature range from 450 to 750oC. Overall, Ni-based alloys corrode by a combination of carbon diffusion and precipitation in the alloy interior and atom migration through surface carbon deposits. The formation of protective surface oxide films provides initial protection against metal dusting, but local rupture of surface Cr-rich oxide films allows rapid carbon diffusion into the alloy. The focus of this research is to advance the understanding of the corrosion mechanisms of Ni-based alloys by characterizing interfacial processes at the nanometer level. In addition to the effect of temperature and environmental chemistry, the mechanistic aspects of metal dusting are discussed with particular attention to the stages of microstructure evolution as degradation proceeds.

Influence of sample thickness and microstructure on metal dusting behavior of NiCrFeAl alloys

“…[28] Further models are described in. [18,22,23,30] The thicker oxide scale with lower stresses on the thinner sample would be more protective against the penetration of carbon, so the first pit appears later. In addition, the higher stresses in the thinner scale of the thicker samples should cause more scale defects (i.e., cracks) than the lower stresses in the thicker scale, which makes it additionally easier for the carbon to reach the metallic surface.…”

“…The metallic substrate supersaturates in carbon and therefore decomposes into a mixture of graphite, oxidic, carbidic, and metallic particles (“metal dust”). [ 8‐30 ] This leads to the formation of pits, and possibly loss of containment. [ 4‐7 ]…”

Synthesis of Ni-Cu-CNF Composite Materials via Carbon Erosion of Ni-Cu Bulk Alloys Prepared by Mechanochemical Alloying

“…During the CE process, spontaneous destruction of bulk metals or alloys in the carbon-containing atmosphere at elevated temperatures (400-600 • C) occurs. Ni and its alloys are known to be among the materials susceptible to the CE process [56,57]. The destruction of the coarse metal particles (or items) starts with the deposition of carbon at the grain boundaries [58,59].…”