| 摘要 |
An object of the present invention is to implement manufacture by rolling silicon steel having a silicon content of 3 wt% or greater, conventionally considered impossible, and by rolling thin sendust sheet. Powder metallurgical fabrication is employed using powder as the starting raw material, and the average crystal grain size of the sheet-form sintered body or quick-cooled steel sheet is made 300 mu m or less, whereby intra-grain slip transformation occurs after slip transformation in the grain boundaries, wherefore cold rolling is rendered possible. In addition, a mixture powder wherein pure iron powder and Fe-Si powder are mixed together in a prescribed proportion is fabricated with a powder metallurgy technique, and an iron-rich phase is caused to remain in the sintered body, whereby cold rolling is possible using the plastic transformation of those crystal grains. Furthermore, when a minute amount of a non-magnetic metal element such as Ti, V, or Al, etc., is added beforehand, it becomes easy to make the iron-rich phase and silicon-rich phase enter into solid solution during annealing, crystal grain growth can be promoted, the magnetic properties of the fabricated steel sheet become roughly equivalent to those of conventional ingot material, and silicon steel sheet exhibiting outstanding magnetic properties can be fabricated. Using this rolled silicon steel sheet, after aluminum is vapor-deposited to both sides of the thin sheet, the aluminum is made to diffuse and permeate into the interior of that thin sheet, and the crystal grain size is coarsened simultaneously, by heat treatment, whereby thin sendust sheet can be obtained which exhibits outstanding magnetic properties equivalent to those of ingot material. The applications of this material can be broadened over a wide range that includes transformers and yoke elements, etc. <IMAGE> |
