The aim of the diploma work was to predict the evolution of the microstructure of a commercially pure titanium alloy Grade 2 during hot rolling. For this purpose, tools that were originally developed for steels and include simulations of strain hardening, dynamic recovery and recrystallisation were modified accordingly and adapted for titanium. Based on microstructural analyses of industrially rolled material and available scientific literature, the material parameters were determined in such a way that the difference between the industrial and simulated microstructures was minimal. With these parameters, a series of simulations were carried out to study the influence of various technological parameters, such as rolling speed, temperature and different times between individual deformations, on the evolution of the microstructure, i.e. on the final grain size.
In addition, a parametric analysis was carried out to study the sensitivity of various material parameters on the kinetics of the processes taking place in the material. The simulations showed that the grain size increases with increasing rolling speed for the selected parameters, which was attributed to the longer time available for normal grain growth. On the other hand, the grain size decreased with decreasing rolling temperature, which is an expected result. The simulation results also showed that changing the times between each deformation within the time intervals allowed by the rolling mill at SIJ Metal Ravne has no significant effect on the final microstructure.
The simulations show the good predictive capability of the modified model as well as its sensitivity to variations in process and material parameters. Therefore, with further development and adjustments, it could become an excellent tool and aid for technologists when planning hot rolling technologies for other grades as well.
|
