Dynamic recrystallization and precipitation behaviors of high-Ti microalloyed high-strength steel during hot rolling

Le résumé fourni par la source

High-Ti microalloyed high-strength steels exhibit complex dynamic recrystallization (DRX) behavior owing to the strong interaction between strain-induced precipitation and austenite recrystallization. To clarify the hot deformation behavior and DRX mechanisms of thick-gauge high-Ti microalloyed high-strength steel, hot compression tests were conducted at 900–1150 °C and 0.01–10 s -1 , and a hyperbolic-sine Arrhenius constitutive model was established based on the Zener–Hollomon parameter. The results show that the flow stress decreases with increasing deformation temperature and increases with increasing strain rate, with a hot deformation activation energy of 386.185 kJ/mol. The softening mechanism gradually evolves from incomplete dynamic recrystallization (DRX) characterized by necklace structures to a more extensive and homogeneous DRX process with increasing temperature. Meanwhile, at low strain rates, abundant strain-induced precipitation of nanoscale (Ti, Nb)(C, N) generates strong Zener pinning, suppressing DRX and promoting necklace-like recrystallization. In contrast, the kinetically suppressed precipitation at 10 s -1 , together with intense adiabatic heating, eliminates the pinning effect and leads to anomalous equiaxed grain coarsening. Finally, processing maps were established to firmly identify the optimum hot-working window at 1050–1150 °C and 0.01–10 s -1 . Furthermore, predictive models for the critical strain ( ) and recrystallized grain size ( ) were developed, providing rigorous theoretical guidance for the industrial thermomechanical processing of high-Ti microalloyed steels.

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