珪素鋼板における等温γ→α変態による {100} 集合組織の形成とその機構

概要

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An investigation has been made to develop {100} texture in silicon steel sheet by an isothermal austenite (γ)→ferrite (α) transformation. Steel sheets alloyed with approximately 2% of silicon, 1% of manganese and 0.1% of carbon were vacuum-annealed and then decarburized in a 20% hydrogen-argon atmosphere containing water vapor. During the vacuum-annealing at the α/γ duplex-or γ-phase temperatures from 900 to 1050℃, a thin layer just below the surface of the sheet transformed to α-ferrite and a strong texture of {100} <011> or {100} <ovw> type developed in the layer. By the subsequent decarburization, the α-ferrite grains in the layer grew toward the thickness center of the sheet, forming a columnar grain structure. The resulted columnar grain structure that inherited the texture of the surface α-ferrite layer exhibited an excellent soft-magnetic properties. The γ→α transformation within the surface layer is considered to be due to a long-range carbon diffusion induced by a manganese dilution in the layer. The selective driving force for the strong {100} texture formation is thought to reside in the anisotropy of the surface energy at the annealing atmosphere-metal interface.
社団法人日本鉄鋼協会の論文
1993-12-01