| 摘要 |
PURPOSE:To stably obtain an iron core material free from surface flaw and having uniform and superior magnetic properties by heating a slab in a protective-gas atmosphere until slab temp. reaches the temp. region where at least a part of intergranular segregation is melted, heating and holding the above slab to and at a specific temp. region, and then carrying out hot rolling. CONSTITUTION:A silicon-containing steel slab is heated until its temp. reaches the temp. region where at least a part of intergranular segregation is melted in a protective-gas atmosphere. Subsequently, the above slab is heated up to 1380-1440 deg.C and held in the above temp. region for 5-60min. After the above heating, hot rolling is exerted, and the resulting plate is cold-rolled once or is cold-rolled twice or more while process-annealed between the cold rolling stages so as to be finished to the final sheet thickness. Then, the resulting sheet is subjected to decarburizing annealing, and, after a separation agent at annealing is applied to the sheet, finish annealing is carried out. Since the coarsening of crystalline grains is inhibited by the above heating prior to hot rolling, the occurrence of band-shaped fine grains can be prevented and excellent magnetic properties can be uniformly obtained. |
