钒：改造未来

Recrystallization characteristics and modelling of microstructure evolution in association with Mini Mill hot rolling of V-N-microalloyed steel

Abstract:

The present project aims to determine the static recrystallization characteristics and flow stress behaviour in association with Mini Mill hot rolling. The equations for recrystallized grain size and kinetics have been established for vanadium and vanadium-titanium steels and used as the basis for a theoretical evaluation of microstructural evolution during hot rolling. The influence of the hot working process parameters have been evaluated regarding the development of microstructure during processing as well as the flow stress of vanadium steels with base compositions (wt¾) of: 0.051%V-0.066%C-0.0151%N-0.63%Mn-0.014%Si and 0.134%V-0.055%C-0.0197%N-1.63%Mn-0.393%Si-0.006%Ti. 
The influence of cooling rate and initial austenite grain size on phase transformation characteristics was also studied. The CCT-diagrams for various austenitization temperatures and cooling rates were established using a dilatometer. 
A computer model MicDel ( developed at SIMR) for predicting microstructural evolution in association with hot rolling has been used in order to optimise rolling schedules for attaining effective grain refinement. 
A model for prediction of the relation between ferrite grain size and austenite grain size, cooling rate as well as the chemical composition of the steel has been developed. The models have been applied to establish how the mini-mill production route can be optimised with respect to quality in the final product.