In this paper, the kinetics of TiN, V(C,N)) and AlN precipitation in microalloyed steel during continuous casting is investigated experimentally and theoretically. The precipitate phase fraction, mean radius, number density and composition are simulated with the thermo‐kinetic software MatCalc and compared with experimental results obtained from transmission electron microscopy analysis. A new methodology for modelling precipitation in cast steel is proposed, which consists of two parts: First, a Scheil – Gulliver simulation, which is carried out to obtain information on the amount of microsegregation during solidification. Then, based on this information, two precipitation kinetics simulations are performed: One with the chemical composition representative for the solute‐poor core of the secondary dendrite arms, the other with the composition of the residual liquid at a fraction of 5%, corresponding to the segregated solute‐rich interdendritic regions. The results of the computer simulations using the new methodology are in good agreement with experimental observation.

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The precipitation of carbides and nitrides in Nb-microalloyed steel is investigated experimentally and theoretically using light optical, scanning and transmission electron microscopy, and the thermokinetic software MatCalc. The simulations are based on a recently developed two-step methodology for precipitation simulation in primary solidification microstructures, where the compositional inhomogeneities from microsegregation are taken into account. The computed segregation is clearly evidenced in electron probe microanalyses of the as-cast microstructure. Based on the results of a Scheil–Gulliver simulation, precipitation kinetics simulations are performed with the chemical compositions corresponding either to the solute-rich interdendritic zone or the solute-depleted dendrite core zone. The predicted phase fractions, mean radii, number densities, and compositions of the precipitates are in good agreement with the experimental investigations.

Precipitation kinetics of Nb(C,N) in microalloyed steels is crucial for the achievement of favoured steel properties. Therefore, numerous experimental studies have been performed in the past and various theoretical models have been developed to describe Nb(C,N) precipitation. However, the experimental data is sometimes contradictory and even the thermodynamic data for NbC solubility in austenite have a large scatter. In this paper, experimental results on the Nb(C,N) and NbV(C,N) precipitation kinetics in deformed and undeformed austenite are reviewed. Based on these data and with the precipitation kinetics module of the software package MatCalc, computer simulations are performed. The predicted interfacial energy of precipitates is adjusted to match the observed kinetics. A comparison between experimental information and simulation, l.e, time -temperature -precipitation (TIP) diagrams, is drawn and discussed. The results of the computer simulations using modified interfacial energies are in good agreement with the experiments.