Applications of Through Process Modelling Developed in VIRSTAR

In February 2004, the outcome of a four-year European collaboration on Through Process Modelling (TPM) of aluminium alloys was presented in Brussels. This was a 17 M euro project in which key research institutes and universities, together with major aluminium companies, developed a series of linked and physically based microstructure models to predict the behaviour of aluminium alloys during fabrication and subsequent processing. Since then, Corus RD&T has implemented the modelling tools developed in the project and integrated them into a comprehensive in house TPM framework called Roll-it. The model framework of Roll-it is constructed by combining a series of sub-models that predict precipitation, work-hardening, recovery and recrystallization. It has been coupled with a finite difference based process model which provides the necessary input variables like strain, strain rate and temperature and applied to predict the evolution of microstructure during thermo-mechanical processing of aluminium alloys. With Roll-it, it is now possible to predict microchemistry, grain structure, and degree of recrystallization at any given point during the fabrication process. In this paper, three TPM applications are presented to illustrate the efficacy of Roll-it. In the first example the aim was to improve reproducibility of properties of hot rolled AA5083. The model showed that the control of dispersoid size during the homogenisation phase and the finish temperature of hot rolling were the critical parameters. In the second example customer's required a sheet product with improved forming characteristics, in particular reduced "roping". TPM was used to simulate recrystallization behaviour during two breakdown hot rolling schemes that produce sheets with different roping behaviour. Finally, Roll-it was coupled with the advanced texture models developed by IMM Aachen to predict the texture evolution during tandem hot rolling and subsequent annealing of a 6xxx-alloy.