Selective leaching of nickel and chromium from Type 316 austenitic steel in oxygen-containing lead–bismuth eutectic (LBE)

Long-term corrosion behavior of martensitic steel welds in static molten Pb–17Li alloy at 550°C

“…[9] protective surface oxide layers inhibit contact between the molten Pb-17Li alloy and the steel matrix, and thus, the oxide surface layers themselves do not suffer from any further direct attack by the Pb-17Li alloy. The surface oxide layers form during the initial corrosion time, called an incubation period, and commonly appeared in the early stage of the liquid Pb-17Li/metal corrosion [18][19][20][21]. However, in this work, a similar oxide layer was found in neither exposure-time samples.…”

Long-term corrosion of austenitic steels in flowing LBE at 400 °C and 10 −7 mass% dissolved oxygen in comparison with 450 and 550 °C

“…In both cases the near-surface zone of the steel does not show depletion in steel constituents beyond the corrosion front. Similar corrosion appearances were observed in LBE with 10 À6 mass% dissolved oxygen, but as a result of local failure of spinel layer (AO), representing general corrosion mode, or Cr-based oxide film (PS) [5,17,18]. Both, selective and non-selective leaching are governed by the transport of solved elements in the boundary layer and subsequent transfer to the liquid metal bulk [6].…”

“…8 c). The first is the result of selective leaching proceeding via non-selective solution of the major steel elements (Ni, Cr, Fe) followed by re-deposition of mainly Fe and partially Cr on steel substrate while Ni and most of Cr are transferred into the bulk of the liquid-metal [5,6]. A sharp change in the concentrations of steel constituents at the steel/depletion zone interface is observed in this case.…”

“…At 10 À6 mass% dissolved oxygen, the austenitic steels mostly show AO accompanied by spinel formation [5,17,18]. With time, after local failure of scale, a local SBA via selective leaching occurs.…”

“…It is indirect evidence that the depleted zone is formed as a result of selective transfer away from the boundary layer into liquid-metal bulk rather than selective solution transport across the steel/liquid metal interface. At the same time, low soluble iron re-deposits on steel substrate if saturation of the liquid metal is approached at the steel surface [5,6].…”