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

• Published in: Metallurgical and materials transactions. A, Physical metallurgy and materials science Physical metallurgy and materials science, 2019-02, Vol.50 (2), p.590-600
• Main Authors: Kasai, Shoki, Ukai, S., Yamashiro, T., Zhang, S., Oono, N., Hayashi, S., Ohtsuka, S., Sakasegawa, H.
• Format: Article
• Language: English
• Subjects: Carbon; Carbon content; Characterization and Evaluation of Materials; Chemistry and Materials Science; Cooling; Cooling rate; Deformation; Dislocations; Dispersion hardening steels; Dynamic recrystallization; Ferrite; Ferritic stainless steels; Hot rolling; Materials Science; Metallic Materials; Nanotechnology; Oxide dispersion strengthening; Radiation; Stainless steel; Structural Materials; Surfaces and Interfaces; Temperature; Thin Films; Transformations
• ISSN: 1073-5623; 1543-1940
• DOI: 10.1007/s11661-018-5056-7

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 Ar 3 (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 μ m). 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.