Effect of Inhibitor Particles on Normal Grain Growth before Secondary Recrystallization of Grain-Oriented Electrical Steels

Abstract

The effect of inhibitor particles on normal grain growth is investigated. Migration of quadruple junction points, instead of entire boundary area, should be dominant during grain growth process according to experimental observations of Fe–3%Si alloys and corresponding regression calculations. However, the evolution of Zener drag induced by inhibitor particles is different from evolution of driving force for grain growth during annealing, and needs to be treated independently in kinetic equation of parabolic growth. An analytic equation is therefore managed to be obtained, of which the predictions agree with experimental observations while certain ambiguity in conventional equations is avoided. The new kinetic equation describes that inhibitor particles can drastically reduce but cannot completely suppress grain growth process which can only practically be inhibited when the average grains size has become large enough. This inhibition effect is not predicted by conventional kinetic equations.

The Role of Slag Carryover on the Non-metallic Inclusion Evolution and Magnetic Behavior in Electrical Steel

“…The important aspects of NMIs in the relevant stages are also indicated in the figure . In general, it is essential to utilize the NMIs (mostly sulfides and nitrides) efficiently to control the growth process of Goss grains during the annealing stages. [35][36][37] The primary function of sulfide inclusions to promote Goss texture during the annealing process and reduce the core loss in the steel sheet is, [38][39][40][41][42] Inhibition of the Goss oriented nuclei growth during primary recrystallization (PRx) annealing Selective dissolution of MnS inclusions during secondary recrystallization (SRx) annealing to allow abnormal grain growth of preserved Goss oriented nuclei during secondary recrystallization (SRx) annealing Eventually, the removal of sulfur from the matrix to the slurry coated oxide layer in the steel sheet It should be noted that decarburization of the steel sheets also occurs during the SRx annealing process. Removal of sulfur from the matrix after recrystallization is essential to reduce further the core loss of the silicon steel.…”

“…[24] To achieve the above functions, the homogeneous distribution of fine sulfide (MnS) inclusions is crucial before the start of the annealing process. [36] The pre-requisite for the homogeneous distribution of fine MnS in the steel product is the complete dissolution of MnS inclusions during the reheating process. The dissolution of MnS in electrical steel strongly depends on the Mn/S ratio, temperature, and size.…”