Early oxidation stages of austenitic stainless steel monitored using Mn as tracer

Abstract

Understanding the mechanism of oxide layer growth on 316 L requires knowledge, e.g., about the reaction front position, oxide phase formation and diffusion paths of the elements involved. We gain essential information for the early stages of oxidation up to 600 °C, utilizing Mn as tracer in a novel experimental approach. Reasoning is based on monitoring implanted Mn in a Mn-free 316 L before and after oxidation. The reaction front is located inside each oxide grain at ∼400 °C but shifts towards the surface at ∼600 °C. Detection of Cr6+ at 600 °C suggests a so far undocumented role of Cr valence state during oxide growth.