Dynamic recrystallization behavior of twin roll cast low carbon steel strip

Abstract

Dynamic recrystallization behavior of twin roll cast low carbon steel strip was investigated in this paper in an attempt to provide guiding deformation parameters for the on line hot rolling. As cast strip was reheated and soaked with austenite grain size similar to the width level of the as cast columnar structure. Tensile test was used and the deformation temperature is in the range of 900 to 1 100°C and the strain rates are 0.01, 0.1 and 1 s-1. Activation energy and stress exponent were determined by regression to be 306kJ/mol and 4.69 respectively. The ratio of critical strain to the peak strain εc/εp is 0.65, and that of critical stress to the peak stress σc/σp is 0.92. Dependence of the peak strain εp on the initial grain size D0 and Zener-Hollomon parameter Z is εp=9.1×10 -4×D00.48Z0.13. Kinetics of the dynamic recrystallization and the recrystallized grain size was predicted using models published. The as cast coarse austenite will be dramatically refined after complete dynamic recrystallization under low deformation temperature and slow strain rate according to the predicting results. © 2009 ISIJ.