Corrosion of 20Kh13 steel in lead melts saturated with oxygen

Abstract

We study the high-temperature interaction (650°C, 500 h) of 20Kh13 chromium steel with melts of stagnant lead saturated with oxygen (CO [Pb] ≈ 6 · 10−3 wt.%). First (up to 200 h), separate islands of Me3O4 oxides (Me: Fe, Cr, Pb) are formed on the steel surface. In the course of time (for 500 h), these islands completely cover the steel surface as a result of lateral growth. The upper part of the oxide layer is formed by the (Fe1 − xPbx) O · Fe2 O3 complex oxide growing from the initial “solid-metal—melt” interface toward the liquid-metal medium. The inner part of the oxide layer is spinel [(Fe1 − xPbx) O · (Fe1 − yCry)2O3] enriched with chromium and formed on the basis of the matrix. Both layers symmetrically grow with respect to the initial “solid-metal—melt” interface. Lead does not penetrate into the steel matrix and is fixed only in the oxide layer.