Experimental Study of the Evolution of Creep-Resistant Steel’s High-Temperature Oxidation Behavior

This study shows that in an atmosphere containing water vapor, the oxide layer on surface of 9CrNB steel MarBN (Martensitic 9Cr strengthened by Boron and MX Nitrides) was formed outer hematite Fe2O3 Cr2O3 inner two-phase Fe3O4 + (Fe, Cr)2O4, which confirmed XRD analysis. Part consisted nodules pores were during increase oxides when present H2O(g) acted surface. The diffusion mechanism at temperatures 600 650 °C longer oxidation times supported “healing process” with a growing Fe presence Cr minor alloying elements. effects elements quantified using concentration profile based quantitative SEM analysis, as well explanation influencing structure chemical composition steel-matrix–oxide interface. In addition to Cr, for content reached requirement exceeding 7.0 wt. % layer, W, Co, Mn, Si also found increased concentrations, whether form Fe-Cr spinel or part continuously distributed Mn2O3 SiO2 After long-term high-temperature oxidation, coarser carbides M23C6 type (M = Fe,W) significantly depleted oxide-layer/matrix zone under very fine particles MC V, Nb, lesser extent particle lattice given phase) observed, higher number per unit area compared state before oxidation. fact consequence through subsurface zone.