Effect of zirconium addition on the microstructure and mechanical properties of ODS ferritic steels containing aluminum

The oxide dispersion strengthened (ODS) ferritic steels with nominal composition of Fe–16Cr–2W–0.5Ti–0.4Y2O3–4Al–1Zr (16Cr–4Al–Zr–ODS) were fabricated by a sol–gel method combining with mechanical alloying and spark plasma sintering (SPS) technique, and the 16Cr–ODS and 16Cr–4Al–ODS steels were prepared for comparison in the same way. Microstructure characterization reveals that in the 16Cr–4Al–ODS steel coarse Y–Al–O particles were formed while in the 16Cr–4Al–Zr–ODS steel finer Y–Zr–O particles were formed. The mean size and number density of the nano-oxide particles in the 16Cr–4Al–Zr–ODS steel are about 25 nm and 2.6 × 1021/m3, respectively. The ultimate tensile strength (UTS) of the 16Cr–ODS steel is about 1045 MPa, but UTS of the 16Cr–4Al–ODS steel decreases to 974 MPa. However, UTS of the 16Cr–4Al–Zr–ODS steel increases to 1180 MPa while keeping a large uniform elongation up to 23%, indicating the enhancement of mechanical properties by Zr addition.