Development of microstructure-based tools for alloy and rolling process design (Microtools) : final report

Project Microtools developed tools to construct processing regime maps combining temperature-time-deformation history with enhanced knowledge of the metallurgical mechanisms during hot rolling, to design improved rolling schedules and chemistries. The dependence of the austenite recrystallisation and precipitation kinetics on the elements Mn, Si, Al and Nb at levels relevant to plate and advanced high strength strip steels was studied using thermomechanical testing and detailed metallography and integrated into equations for use in hot rolling models. The softening retardation potential of the alloying elements investigated was found to decrease in the order Nb>>Al>Si. A new methodology for quantifying the recrystallised austenite fraction using EBSD maps and austenite grain reconstruction software was developed. Processing regime maps were constructed for representative plate and hot rolled strip rolling schedules from which pilot rolling trials were designed and performed to successfully validate the new models.