Deformation-Induced Dynamic Ferrite Transformation During Hot-Rolling in Oxide Dispersion-Strengthened Ferritic Steel with 9 Wt Pct Cr Content.

9CrODS steel, a candidate fission and fusion structural material, was subjected to hot-rolling with varying parameters of surface temperature and cooling rate just after hot-rolling. The deformation-induced dynamic ferrite transformation was confirmed at the rolling temperature 805 °C above Ar₃ (780 °C). This transformation exhibits three characteristic features: transformation for extremely short duration (0.044 second), retaining carbon content equal to the original without long-distance carbon diffusion, and elongated coarse ferrite grains (10 μm). The massive transformation was proposed for the dynamic ferrite transformation from the hot-rolled austenite. The driving force for massive transformation was quantitatively estimated considering dislocations accumulated by hot-rolling. It was also shown that the oxide particles in 9CrODS steel play a critical role for dynamic ferrite transformation by suppressing the dynamic recrystallization at hot-rolling. [ABSTRACT FROM AUTHOR]