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Phase transformations play a significant role during the technical heat treatment of steel. For instance a controlled transformation in an annealing process allows for the production of multiphase steels. In this investigation the proeutectoid ferrite precipitation will be looked into. The transformation kinetics can be described as diffusion controlled, yet another type of kinetics is also thinkable which would be controlled by interface mobility. Isothermal transformation dilatometry has been performed on high carbon steel grade samples. In a detailed metallographic analysis the samples were examined according to probable nucleation sites of proeutectoid ferrite. The simulations in this work have been performed using the software MICRESS. MICRESS is based on the multicomponent multiphase-field model. Besides diffusion it also takes finite interface mobilities into account. It allows for multidimensional calculations, which illustrates the ferrite precipitation in real microstructures. For comparison reasons simulations in a one-dimensional domain have been performed using the commercial program DICTRA.