Abstract: The hot deformation behavior of a Mn-Cu-V weathering steel was investigated at temperatures ranging from 850 to 1050°C and strain rates ranging from 0.01 to 5 s^-1 using MMS-300 thermal-mechanical simulator. The activation energy for dynamic recrystallization and stress exponent were calculated to be 551 kJ/mol and 7.73, respectively. The accurate values of critical strain were determined by the relationship between work hardening rate and flow stress (θ-σ) curves. The hyperbolic sine constitutive equation was employed to describe the relationship between the peak stress and Zener-Hollomon parameter during hot deformation. The interaction between dynamic recrystallization and dynamic precipitation of V(C,N) at a low strain rate was analyzed. The results showed that precipitation particles size of weathering steel increased with increasing strain at deformation temperature 950°C and strain rate 0.1 s¡1. The calculation results of the recrystallization driving force and pinning force showed that dynamic precipitation could retard the progress of dynamic recrystallization but not prevent it while the pinning forces is less than driving force. On the contrary, dynamic precipitation can effectively prevent the progress of dynamic recrystallization.

Key words: Weathering steel, Critical strain, Dynamic recrystallization, Dynamic precipitation