Microstructural Characterization of Novel ZrO2 Dispersion-Strengthened 9Cr Steel by Spark Plasma Sintering

Abstract

Technologically important Oxide Dispersion-Strengthened steels are synthesized using ZrO2 as a dispersion strengthener instead of conventionally used Y2O3. Powder metallurgical route followed by spark plasma sintering is adopted for synthesizing the material. Detailed microstructural characterization revealed a fine-grained microstructure with finer dispersoids in as-sintered and normalized condition. The stable microstructure is found to be retained even after subjecting the samples at 973 K for as long as 1000 h for long-term thermal aging trials, indicating at a possible superiority of this material over the conventional Oxide Dispersion-Strengthened steels. The yield strength is calculated by making use of microstructural parameters and predictive models, both of which shown a good agreement. Mechanical property analysis through hardness measurements was correlated with microstructural observations and compared with the conventional Oxide Dispersion-Strengthened steels. The collective results indicate ZrO2 as a potential alternate dispersoid for strengthening steel and future scope for vast exploration.