Open Access Conference Proceedings

During recrystallisation annealing after cold forming, it has been repeatedly observed that there is a critical range of strains beyond which enormous coarsening of the statically recrystallized grain occurs. It can be assumed that similar behaviour can also be expected during hot rolling with static recrystallisation (SRX) between passes, especially in the first passes at the highest temperatures. This paper aims to experimentally determine the effect of strain on the grain size and to find the critical strain range for grain coarsening. For this purpose, a plain strain compression test (PSCT) was performed on the Hydrawedge II simulation module cooperating with the electrical and hydraulic systems of the HDS-20 simulator (Gleeble 3800). A total of 18 tests were performed for three different deformation temperatures (1000, 1050 and 1100 °C) and 5 different interpass times after deformation (1 to 200 s). Thanks to PC simulation using FEM in the Simufact Forming program, the equivalent strain distribution in the deformed sample was determined. Thanks to this, it was possible to determine the dependence of the size of the original austenite grain after deformation (obtained metallographically) on delay at a given temperature for a strain range of 0.02 to 0.51. Based on the experiments, graphs of the dependence of the size of the original austenite grain on the equivalent strain were compiled. The results showed that in the strain range of 0.05 to 0.15, there was an enormous grain coarsening, especially at the highest temperatures. The achieved results were compared with theoretical values obtained using calculations of SRX kinetics, recrystallized grain size and grain coarsening kinetics.

Keywords: Microalloyed steel, hot rolling, recrystallisation, grain growth, PSCT

© This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.