Effects of Thermal Aging on the Oxidation Behavior of 316L Austenitic Steel in 600 °C Supercritical Fired Boiler: Mechanism Based on Interface Features

Abstract

The oxidation behavior of 316L austenitic steel after thermal aging process at 600 °C for 6 h was investigated in the supercritical water (600 °C/25 MPa) with 1000 h. Results showed that the grain size and the proportion of high angle grain boundaries (HAGB) increased in the steel after thermal aging process, with the observation of micro-textures. The weight gain rate of the steel after aging process increased, presenting the decreased Cr₂O₃ contain in the oxide layer, which resulted in the increasing diffusion rate of Fe and O ions in oxide layer. The molecular dynamics simulation results confirmed the high oxidation rate in HAGB and micro-textures for the 316L steel after aging process.