On-line model for control of hot rolling of austenitic steel strips

摘要

The on-line model of strip rolling for austenitic steels is described in the paper. Three components are included in the model. The first is a new thermal model, which is based on an analytical solution of the Fourier equation. Thermophysical properties of the austenitic steels are introduced in the model. The numerical procedure, which designs a rolling schedule, is the second part of the model. The rolling velocities and the reductions in subsequent passes are determined by a solution of a set of non-linear equations, which compose continuity condition and energy balance for all stands. The problem is solved using optimisation techniques with constraints, that allows imposing of the technological limitations on the solution. The adaptive procedure is applied to adjust coefficient in the flow stress equation during the on-line work of the model. Microstructure evolution model is the third part of the system. This model is based on semi-empirical equations describing microstructural phenomena for austenitic steels. The micrustructural model is included in the temperature calculations, but it does not take part in the control of the rolling process directly. Its task is to supply information regarding the microstructure and mechanical properties predicted for the current rolling technology, designed by the sys-tem. Description of all the developed models is given in the paper. Results of numerical experiments including calculations of rolling schedules are presented.