The main work of this thesis is to identify and quantify the key material parameters that play a decisive role in the development of microstructure during the rolling process of aluminum alloys. The determination of these parameters enabled more precise adjustments to the rolling process input parameters, leading to more effective control over the microstructural evolution and, consequently, the final properties of the material. This allows for the improvement of the mechanical properties of industrially produced aluminum semi-products, while also increasing the flexibility and efficiency of the entire production process.
The thesis is based on performing numerical simulations of rolling, supported by laboratory and industrial measurements as well as microstructural characterization. The rolling simulation model is based on coupling the macroscopic description of the process, grounded in continuum mechanics, with a microscopic model for predicting microstructural evolution, which is based on mean-field theory. Using process parameters or predefined rolling schedules, the macroscopic model calculates the local evolution of strain, temperature, and strain rate at selected points across the cross-section of the rolled material. These three parameters for the selected points then serve as input data for the microstructural evolution simulation. The microstructural model enables the simulation of the complete grain size distribution, flow stress, accumulated strain, softening rate, and the process of static recrystallization.
The central goal of this thesis is to compare and evaluate the simulated microstructure with the microstructure of industrially rolled strips at different stages of the hot rolling process, namely in the cast state, during hot rolling, and after hot rolling for the selected alloy EN AW-6082.
The rolling simulation model has proven to be suitable for accurately predicting the average grain size, with deviations between the simulated and industrially obtained microstructures being less than 3.5 µm. Critical variables, such as the mobility of high-angle grain boundaries and the likelihood of nucleation during static recrystallization, were identified as essential for achieving consistency between simulations and industrial results. The findings will contribute to the development of new methods for optimizing production processes and improving the quality of final products made from aluminum alloys.
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