Particle-Size-Grouping Model of Precipitation Kinetics in Microalloyed Steels

The formation, growth, and size distribution of precipitates greatly affects the microstructure and properties of microalloyed steels. The computational Particle-Size-Grouping (PSG) kinetic models were developed to simulate precipitate particle growth due to collision and diffusion mechanisms. Firstly, the standard PSG method for collision is clearly explained and verified. Then a new PSG method is proposed for the diffusion-controlled precipitate growth with complete mass conservation. In comparison with the original population calculation, the PSG method saves significant computation and preserves enough accuracy for system with a large range of particle sizes. Finally the new PSG method is applied to simulate the precipitated fraction of AlN, and size distribution of NbC during isothermal ageing processing, and good matches are found with experimental measurements.