Abstract
Oxide dispersion strengthened (ODS) steels with different contents of zirconium (denoted as 16Cr ODS, 16Cr-0.3Zr ODS and 16Cr-0.6Zr ODS) were fabricated to investigate the effects of Zr on strengthening mechanism of Al-alloyed 16Cr ODS steel. Electron backscatter diffraction (EBSD) results show that the mean grain size of ODS steels could be decreased by Zr addition. Transmission electron microscope (TEM) results indicate that Zr addition could increase the number density but decrease the mean diameter and inter-particle spacing of oxide particles. Furthermore, it is also found that in addition to Y-Al-O nanoparticles, Y-Zr-O oxides with finer size were observed in 16Cr-0.3Zr ODS and 16Cr-0.6Zr ODS steels. These changes in microstructure significantly increase the yield strength (YS) and ultimate tensile strength (UTS) of ODS steels through mechanisms of grain boundary strengthening and dispersion strengthening.
Highlights
Oxide dispersion strengthened (ODS) steels have been considered as promising fuel cladding materials for advanced nuclear systems and blanket materials for fusion power systems [1]
Both large and small precipitates can be observed in the Transmission electron microscope (TEM) image
A density of oxide particles within the grain can be observed in the small grains of 16Cr-0.3Zr ODS
Summary
Oxide dispersion strengthened (ODS) steels have been considered as promising fuel cladding materials for advanced nuclear systems and blanket materials for fusion power systems [1]. Dong et al investigated the effects of hafnium (Hf) addition on the microstructure and mechanical performance of Al-alloyed high-Cr ODS steels, and found that a large number of refined Y-Hf-O precipitates were formed instead of coarse Y-Al-O. Y-Ti-O clusters in ferrite matrix [22,23] It seems that Zr and Hf are more effective than Ti. The zirconium has prominent nuclear properties and smaller thermal neutron capture cross-section than Hf [24]. The zirconium has prominent nuclear properties and smaller thermal neutron capture cross-section than Hf [24] From this point of view, Zr is a more appropriate choice to improve the mechanical properties of Al-alloyed high-Cr ODS steels. It is necessary to further investigative the effect of Zr addition on microstructure and tensile strengths of Al-alloyed high-Cr ODS steels. Improvement of YS and UTS of two ODS steels with Zr addition was explained based on different strengthening mechanisms
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