By establishing the intra-granular ferrite nucleation model and conducting a series mathematical calculation, it was found that the nucleation energy of inclusion in irregular shape is lower than that in spherical shape, which is easier to induce the ferrite nucleation. Moreover, the influence factors of intra-granular ferrite nucleation induced by spherical inclusions were also analyzed. The results show that it is adverse to the nucleation of ferrite when the inclusion size is too small, while it has little effect when the size is larger than 0.15μm. Besides, the smaller of the wetting angle, the easier of the nucleation. When the wetting angle is between 70° and 90°, the ferrite is easily induced by spherical inclusions in the form of normal triangular pyramid. However, when the wetting angle is less than 70°, the ferrite is precipitated in the form of spherical. The precipitation rate of ferrite in the form of triangular pyramid is higher than that of spherical. A group of experiments were also verified that irregular inclusions could induce the nucleation of ferrite, while it had little effect when the size is larger than 0.15μm.
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