Evolution of oxide film of a new martensitic steel 9Cr3W3Co in supercritical water. (December 2022)

• Record Type: Journal Article
• Authors: Shang, C.G.; Zhou, Z.G.; Wang, F.; Lu, Y.H.
• Is Part Of: Corrosion science. Volume 209(2022)
• Publication Date: 2022-12
• Subjects: A: Ferritic-Martensite steel -- B: TEM -- C: Oxidation -- Supercritical water; Corrosion and anti-corrosives -- Periodicals; 620.11223
• DOI: 10.1016/j.corsci.2022.110771
• Languages: English
• ISSNs: 0010-938X

Abstract

Abstract: The oxide evolution of 9Cr3W3Co martensitic steel in the supercritical water environment at 650 °C and 30 MPa was studied. The results indicated that a double-layer oxide film, composed of a columnar Fe3 O4 outer layer and a fine grain FeCr2 O4 /Fe3 O4 spinel mixed inner one, that thicknesses followed a sub-parabolic law, was formed. The FeCr2 O4 first grew along various boundaries, then grew into lath along subgrain boundary, dislocation line or by bulk diffusion. After a continuous Cr-rich oxide layer was formed at the inner oxide layer/matrix interface, the inner layer was gradually completely oxidized, which significantly slowed down the oxide rate. Highlights: The growth mechanism of oxide film of a new ferritic-martensite steel 9Cr3W3Co was investigated. Preferential oxidation channels were related to various boundaries of hierarchical martensite microstructure. FeCr2 O4 particles grew into lath interior along subgrain boundary and dislocation line, or by bulk diffusion. The continuous and dense Cr-rich oxide layer significantly slowed down the oxide rate.