The master thesis "Approach to industrial manufacturing a critical product – hot rolling of plates dimensions 8 x 2500 mm of superaustenitic steel grade 1.4539" was prepared with the aim of determining the possibility of hot rolling a critical product of dimensions 8 × 2500 mm on a blooming rolling stand in a hot rolling mill of the company SIJ Acroni d.o.o.
The reversible rolling stand blooming is used for hot rolling heated slabs into thick plates and prestrips for further rolling on the steckel rolling stand. Steel 1.4539 is a highly alloyed superaustenitic steel with increased levels of chromium, nickel, molybdenum, and copper, giving it exceptional properties in highly corrosive environments and in the presence of chlorine. Due to its high alloy content, it has good mechanical properties and a high no recrystallization temperature of 1102 °C.
In the master's thesis, rolling simulations were carried out using mathematical models in the Alfa program, thermomechanical simulations, and microstructure development with the RSProSim tool. Initially, simulations were performed for sheets of dimensions 8 × 1560 mm and 8 × 2060 mm, where the results showed almost complete recrystallization, with dynamic and static recrystallization. The average grain size was 7 μm, with the largest grain size at 17 μm. This was followed by industrial rolling, which confirmed the accuracy of the initial simulations. Due to favourable results, a decision was made to design the rolling technology for a sheet with dimensions of 8 × 2500 mm.
Simulations for the new dimension predicted higher rolling forces, which were similar up to the 13th pass, after which they began to increase linearly. The thermomechanical simulation predicted a drop in forces after the 13th pass. Both simulations confirmed the feasibility of industrial rolling. The microstructure development simulation predicted an average grain size of 11 μm and a maximum grain size of 27 μm, with at least 10% of the grains not recrystallized.
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