| 摘要 |
PURPOSE:To obtain an iron core material free from surface flaw and having uniform and superior magnetic properties by applying light rolling reduction to a slab prior to heating, applying heating to the slab in a protective-gas atmosphere until the slab temp. reaches the temp. region where at least a part of intergranular segregation is melted, and then subjecting the slab to heating and holding to and at a specific temp. CONSTITUTION:Rolling reduction is applied to a silicon-containing steel slab at 1-10% rolling reduction, by which the coarse grains in the slab are broken and refined. Subsequently, the slab is heated in a protective-gas atmosphere until its temp. reaches the temp. region where at least a part of intergranular segregation is melted. Then, the slab is heated to 1380-1440 deg.C and held in the above temp. region for 5-60min. After the above heating, the slab is hot-rolled, 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 sheet is subjected to decarburizing annealing, and, after a separation agent at annealing is applied to the sheet, finish annealing is carried out. By this method, the occurrence of band-shaped fine grains can be prevented, and superior magnetic properties can be uniformly obtained. |
