기계적 합금화 공정으로 제조된 Fe-14Cr Ferritic 산화물 분산 강화(ODS) 합금 강의 고온 산화 거동

Abstract

This study investigates the oxidation properties of Fe-14Cr ferritic oxide-dispersion-strengthened (ODS) steel at various high temperatures (900, 1000, and 1100oC for 24 h). The initial microstructure shows that no clear structural change occurs even under high-temperature heat treatment, and the average measured grain size is 0.4 and 1.1 μm for the as-fabricated and heat-treated specimens, respectively. Y–Ti–O nanoclusters 10–50 nm in size are observed. High-temperature oxidation results show that the weight increases by 0.27 and 0.29 mg/cm2 for the asfabricated and heat-treated (900oC) specimens, and by 0.47 and 0.50 mg/cm2 for the as-fabricated and heat-treated (1000oC) specimens, respectively. Further, after 24 h oxidation tests, the weight increases by 56.50 and 100.60 mg/cm2 for the as-fabricated and heat-treated (1100oC) specimens, respectively; the latter increase is approximately 100 times higher than that at 1000oC. Observation of the surface after the oxidation test shows that Cr2O3 is the main oxide on a specimen tested at 1000oC, whereas Fe2O3 and Fe3O4 phases also form on a specimen tested at 1100oC, where the weight increases rapidly. The high-temperature oxidation behavior of Fe-14Cr ODS steel is confirmed to be dominated by changes in the Cr2O3 layer and generation of Fe-based oxides through evaporation.