To execute rolling for silicon steel having a specified Si content by kneading silicon steel metal powder with agar in which sol-gel transformation occurs and water as a binder, executing sintering after molding to produce a sintered body having the not more than the specified average crystal grain size and specified thickness and executing rolling.
A kneaded material is sintered to produce a sintered body with ≤300 average crystal grain size and ≤5 mm thickness, which is rolled to a required thickness to obtain silicon steel in which the content of Si is controlled to ≥3, preferably, to 10 wt.%. The amt. of agar to be added is preferably controlled to 0.6 to 4.0 wt.%. The amt. of water to be used mixedly with the agar is preferably controlled to 7 to 15 wt.%, and when forming the binder, the temp. is desirably controlled to 92 to 96°C at which the agar is sufficiently melted, but, desirably, the kneading temp. with the metal powder is controlled to 60 to 65°C, and the extrusion molding temp. is controlled to 50 to 55°C. The sintering temp. differs in accordance with the compsn., average grain size, raw material powder, but is generally controlled to 1150 to 1300°C, and it is executed preferably in a gaseous hydrogen atmosphere or in a vacuum.
MAKITA AKIRA
SAIGO TSUNEKAZU
SEKIDO MASAKATSU
ISHII YASUSHI
NORO YOSHIHISA
SHIMIZU SHOKUHIN KAISHA