There is a vast variety of steels resulting from different chemical compositions, but even more from different processing conditions. The interplay of temperature and time, degree of deformation and chemistry, especially microalloying additions, play a crucial role in microstructure evolution and the resulting mechanical properties . From the perspective of microalloying, niobium precipitates on the nanometer-scale play an important role . The formation of such precipitates is still not fully understood at the atomic level and several questions regarding effective precipitate size, chemistry on the atomic scale and the influence of local deformation degrees during the hot rolling need to be addressed.
In the frame of this work, low-carbon low-alloyed steel ingots containing different defined concentrations of Nb (0-0.02-0.04-0.08 mass-%) were produced and respective recrystallization curves were recorded by doing double-hit compression tests in a thermo-mechanical deformation simulator. Subsequently, for each alloy, several states – before, during and after recrystallization retardation – were investigated by means of atom probe tomography and differences in the chemical distribution of Nb precipitates were analyzed.