Formulation of the Decrease in Dislocation Density of Deformed Austenite Due to Static Recovery and Recrystallization.

Abstract

Decrease in dislocation density (ρ) in deformed austenite of Si-Mn steel and Nb added steels due to static recovery and recrystallization has been investigated. By comparing the flow stress measured at the second pass of a double compression test and the fraction of recrystallized austenite of the specimen quenched at a certain time after deformation, the change in ρ due to static recovery has been separated from the total change of ρ. The change in ρ due to static recovery has been formulated as functions of the concentration of Nb (Nb%), deformation conditions and time after deformation. The recovery process is mainly controlled by the climbing of dislocations in the case of higher deformation and holding temperature (DT) and lower Nb%, while it is mainly controlled by the annihilation of dislocations with opposite Burgers vectors in the case of lower DT and higher Nb%. Recovery is retarded by an increase in austenite grain size, a decrease in DT and an increase in Nb%.