Effect of Recrystallisation on the Dispersed Phases of ODS Steel PM2000

Balancing strength and ductility is a key issue for oxide dispersion-strengthened (ODS) steel. Recrystallization is an effective method to achieve this balance. A thorough understanding of the evolution of the dispersed phases before and after recrystallization is of great significance to the design of the recrystallization method of ODS steel and the regulation of its performance. In this study, the dispersed phases in recrystallized ODS steel PM2000 were studied, and compared with that of as-rolled steel. In recrystallized steel, the aggregation of dispersed phase is intensified, the average size of nanoparticles increased, and the number density decreased, and the overall chemical composition of the oxide dispersed phases is closer to Y_1.5-2.0AlO_x. Small-sized dispersed phases, YAlO₃, Al₂Y₄O₉, and YCrO₃, and large-sized dispersed phases, TiC carbide and Al-rich oxide, were identified in the recrystallized steel. The recrystallization induced the formation of YCrO₃ oxides and many TiC carbides with very large sizes. The evolution of the dispersed phase in the recrystallized steel is attributed to the dissolution and reprecipitation of the small-sized dispersed phase during the recrystallization process.