Oxidation of stainless steel 316L – Oxide grains with pronounced inhomogeneous composition

Abstract The formation of oxide grains with pronounced inhomogeneous elemental distribution of Cr and Fe is reported for AISI 316 L stainless steel during the early stages of oxidation at 800 °C. Each oxide grain essentially consists of consecutive Cr-rich and Fe-rich layers parallel to the surface. Local elemental distribution, interplanar spacing and absence of grain boundaries or misorientation were characterized by state-of-the-art TEM. The oxide grains exhibit mainly corundum-type structure. Aspects of the oxide formation mechanism are discussed considering earlier findings, indicating a broader relevance of the new observations regarding the early stages of oxidation of austenitic stainless steel.