The true stress - strain curves of Nb- bearing low carbon steel Q345C (0.056C

1.20Mn

0.052NB

0.033V

0.012Ti

0.005 2N)52 mm concasting thin slab during high temperature deformation by CSP (compact strip production) rolling have been simulated and studied by Gleeble-1500 thermal simulation tester

and the mathematical model and critical conditions of dynamic recrystallization have been obtained

that are Z = 9.7 x10

11

exp (25 ε

c

and Z = 1.77 x 1012 exp (15.8 ε

s

)

where Z- deformation factor

ε

c

- critical deformation of initially occurred dynamic- recrystallization

ε

s

- critical deformation of complete recrystallization. It is available to decrease mixed grain size structure in plate by utilizing recrystallization model to avoid rolling in incomplete recrystallization zone between rolling pass

.