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A cellular automata model was established to simulate grain coarsening processes pinned by second-phase particles. The influences of particle coarsening, precipitation, growth and dissolution, which contain complex changes of size and number density of the particles, on the grain coarsening kinetics were investigated by considering the following two factors: average pinning force per particle and particle number density. The simulation results showed that the average pinning force per particle was related to the particle size, but little influenced by the particle number density. The investigations about the grain boundary/particles interactions showed that the increase of number fraction of particles, which located at the grain boundary junctions, should be the reason for the increase of average pinning force per particle. Then the limiting grain size was researched and compared to the results of some other models. The results showed that the average number of particles to stagnate a grain was related to both the number density and size of particles. At last, the comparisons between the present simulation results and the other simulation and experimental results showed that the present models were efficient in simulating the grain coarsening processes pinned by second-phase particles. [ABSTRACT FROM AUTHOR]

A phase-field model was revised to study the abnormal growth of Goss grains during the annealing process in Fe-3%Si steels, in which the interaction between the second-phase particles and Goss grain boundaries (GBs) was considered. The results indicate that the abnormal growth of Goss grains occurs due to the different dissolvability of the particles at Goss GBs compared with the other GBs. Moreover, the degree of abnormal growth increases first and then decreases with an increasing particle content. Meanwhile, the size advantage of Goss grain can further promote the degree of abnormal growth. Two types of island grains were found according to the simulated results, which is consistent with the experimental observations. A proper GB dissolvability of particles is the key factor for the formation of isolated island grains, and a higher local particle density at GBs is the main reason for the appearance of serial island grains. These findings can provide guidance for the desired texture control in silicon steels. [ABSTRACT FROM AUTHOR]

The effect of the solid solution of second-phase particles on the austenite grain growth behavior at different heating temperatures and holding times of Nb-Ti high-strength IF steel is examined. The experimental results showed that the solid solubility of Nb in austenite increased significantly with temperature, dispersion and fine second-phase particles continued to dissolve in austenite. The pinning effect weakened and the austenite grains increased slowly. When temperature reached 1050 °C, a large number of second-phase particles (NbC, TiC, etc.) gradually dissolved in austenite. The solid solubility of microalloyed elements in austenite used for testing steel was different. To make these elements dissolved completely and, at the same time, obtain fine-grained austenite, heating temperature needs to be kept between 1050–1100°C and the holding time limited to 30–40 min. The austenite grain growth model is constructed based on the experimental data. The calculated values are in agreement with the experimental results. [ABSTRACT FROM AUTHOR]