The effect of Si increase on microstructure and mechanical properties of multi-nano-oxide dispersion strengthened steel

Two 12Cr ODS steels with nominal compositions of Fe-12Cr-1Al-0.5Zr-0.35Y₂O₃-xSi (x = 1 and 2 wt%, respectively) were successfully fabricated. In both steels, a high number density of nanoparticles was produced as dispersion strengthening precipitates. These nanoparticles were identified to be nano-oxides of various types of Y-Al-O, Y-Si-O, and Y-Zr-O, and each type exhibited a different feature size. Increasing the Si content from 1 to 2 wt% brought a twofold benefit, by further refining matrix grains and producing more ultra-fine Y-Si-O and Y-Zr-O nanoparticles. In addition, the mechanical strengths were improved without the sacrifice of plasticity at 973 K.