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.