Effects of aluminum on microstructure and mechanical behavior of 14Cr-ODS steels

Two kinds of ODS ferritic steels with nominal compositions (wt.%): Fe-14Cr-4.5Al-1W-0.35Y2O3 and Fe-14Cr-0.5Ti-1W-0.35Y2O3 have been fabricated by mechanical alloying of a pre-alloyed gas atomized powder with nano yttria powders and then consolidated by hot isostatic pressing. The effects of minor alloying elements Al and Ti on the microstructure and mechanical properties of the fabricated ODS steels have been investigated. Microstructural characterization revealed that Y-Ti-O and Y-Al-O dispersed particles were formed in the 14Cr-Ti-ODS steel and 14Cr-Al-ODS steel respectively, and the particle size of Y-Ti-O is much smaller than that of Y-Al-O. The tensile property test demonstrated that the 14Cr-Ti-ODS steel shows high strength but poor plasticity, while the 14Cr-Al-ODS steel has low strength but rather good plasticity. 14Cr-Al-ODS steel has much higher impact energy than that of 14Cr-Ti-ODS steel at the same testing temperatures.