Effect of the addition of Y and Y2O3 on microstructure and mechanical properties of 15Cr-15Ni ODS steel

15Cr-15Ni ODS steels with the addition of Y or Y2O3 were fabricated via the mechanical alloying and hot isostatic pressing, followed by forging treatment (named as 15Cr-15Ni-Y and 15Cr-15Ni-Y2O3, respectively). The morphology of as-milled powders of 15Cr-15Ni-Y was flatter than that of 15Cr-15Ni-Y2O3. As-forged samples were characterized by high-resolution transmission electron microscope. The oxide particles in both 15Cr-15Ni-Y and 15Cr-15Ni-Y2O3 ODS steels were identified as δ-Y4Zr3O12. The mean size and number density of dispersed nanoparticles in 15Cr-15Ni-Y and 15Cr-15Ni-Y2O3 ODS steels were 13.6 nm, 2.5 × 1022/m3 and 12.8 nm, 5.5 × 1022/m3, respectively. The tensile test at room temperature and 700℃ indicated that the tensile strength of 15Cr-15Ni-Y was lower than that of 15Cr-15Ni-Y2O3 ODS steel, while the total elongation of 15Cr-15Ni-Y was higher. The theoretical value based on the strengthening mechanism was calculated and discussed as well.