Microstructure and Oxidation Behavior of C‐HRA‐5 Austenitic Heat‐Resistant Steel in Air at the Temperature Range of 650–750 °C

Abstract

This study investigates the oxidation behavior and microstructure characterization of C‐HRA‐5 (i.e., a new austenitic heat‐resistant steel) in the air at temperatures ranging from 650°C to 750°C over a 1000‐hour duration. The oxidation behavior and mechanism were analyzed using gravimetric evaluation, thermodynamic analysis, microscopic morphology, and microstructure characterization. The results indicate that the oxidation behavior follows a parabolic law at each temperature. With increasing the temperature, the oxide film gradually grows and transforms from small lump particles to strips and needles, eventually covering the entire substrate surface over time. Moreover, long‐term oxidation exposure promotes the formation of various phases, including M23C6, σ, MX, Z, nano‐sized Cu‐rich, and Laves phases, within the metallic substrate. Considering potential applications in new generation power plants, this study provides a solid foundation to disclose the possible oxidation of C‐HRA‐5 austenitic heat‐resistant steel at high temperatures.This article is protected by copyright. All rights reserved.