Simple model for carbonitride dissolution in microalloyed steels

Based on local equilibrium at the moving phase boundary and diffusion control a simple but comprehensive model concerning the carbonitride dissolution kinetics has been constructed. This model describes the evolution of a single particle or a distribution of particles in a finite austenite matrix with annealing temperature or time. It is shown that at temperatures below the dissolution temperature of carbonitrides the particle size decreases rapidly in early stages and then slows down approaching the equilibrium state. When the temperature, however, exceeds the dissolution temperature of precipitates the particles will be completely dissolved. The time evolution curves of particle size and volume fraction drop quickly and level off at certain temperatures. In contrast, the volume fraction and mean radius of precipitates decrease slowly first at lower temperatures and then drop drastically at higher temperatures. Finally the present model has been validated by the experimental data in the literature.