Papers by Author: W. Mao

Abstract: The precipitation behaviors of fine MnS and other second phase particles in hot band, decarburized sheet and 875 oC annealed sheet before secondary recrystallization of conventional grain oriented electrical steel were investigated. It is indicated that the small particles as inhibitors would dissolve in the matrix during cold rolling, and precipitate again in following annealing treatment. The particles inside grains would keep retarding the grain boundary migration. It was found that the particle densities in all grains were quite different before initiation of secondary recrystallization and might be grain orientation dependent, in which Goss grains showed higher particle density. It is expected that the grain boundaries would move towards the grains with lower particle density more easily and promote the rapid growth of Goss grains. The reason for difference of particle densities in different grains is quite complicated. The influence of possible different dislocation densities and the different precipitation behaviors of second phase particles are mentioned.

Abstract: The compact strip processing technology and the technologies for conventional grain oriented electrical steels were used to process the low cost grain-oriented electrical steel successfully, in which the reheating temperature for hot rolling was about 1150 oC, and strong Goss texture was obtained after the secondary recrystallization. It is indicated that the density of inhibitor particles produced under the condition of low temperature hot rolling was high enough to induce the necessary secondary recrystallization during final annealing, so that many Goss grains could grow. The mis-orientations of Goss grains to the recrystallization matrix were calculated and observed. High angle boundaries enveloped frequently Goss grains, while the growth of other grains would have the possibility to meet low angle boundaries or low mobile boundaries. Goss grains neighboring larger size grains might be protected by the further precipitation of inhibitor particles in high angel boundaries during the temperature rising stage of the secondary recrystallization and survived somehow after the growth competition.

Abstract: A reaction stress model is introduced in this paper and its applications for the crystallographic texture simulation are also discussed with the comparison to the classic Taylor type model and the self consistent model. This model took the external deformation stress tensor as an initial point, and the activation process of slip systems as well as the orientation evolutions was simulated step by step. Certain relaxation of reaction stress were introduced during tensile or drawing deformation, which predicts the tensile direction distribution along the orientation line between <111> and <100> in the inverse pole figure besides the <111> and <100> fiber texture. The simulation agrees with the common experimental observations. The model supplies a simple way to follow the deformation process in the main part of polycrystals, in which the effect of grain orientation and its interaction with the surrounding matrix are considered.