9CrWTi-Y₂O₃/ferritic martensitic steels prepared by mechanically alloyed and spark plasma sintering

9CrWTi-0.35%Y₂O₃ oxide dispersion strengthened ferritic-martensitic steels were prepared by mechanically alloying (MA) and spark plasma sintering (SPS). SPS temperature and displacement measurement, OM, FE-SEM, TEM and EDX were employed to characterize the shrink curve, the microstructures and chemical composition evolution before and after heat treatment. The tensile properties at room temperature were also investigated by electronic tensile test. The result shows that a liquid phase sintering feature is exhibited in 9CrWTi/FMs and 9CrTWi-0.35%Y₂O₃/FMs. The density and tensile strength of 9CrWTi-0.35%Y₂O₃/FMs increase with temperature and pressure, while porosity and grain size decrease and total elongation is only about 2%. Dispersoids about 5-20 nm enriched in Y—Ti—O are uniformly distributed in the matrix. The microstructures are of equiaxed ferritic, slender lath martensite, and mainly equiaxed and residual ferritic SPS, after 10%NaCl water solution quenching and tempering at 750 ℃, respectively. The 9CrWTi-0.35%Y₂O₃/FMs by SPS exhibits ultimate tensile strength and yield strengthen of 1554 MPa and 1430 MPa, and a total elongation to fracture of 1.8%, while after salt water quenching and tempering, which successively change to 1198 MPa, 1006 MPa and 12.8%, respectively.