| 摘要 |
An oriented magnetic steel sheet with a very low core loss and a process for manufacturing it at a lower cost are disclosed. The steel sheet consists essentially of Si: greater than 3.0% and at most 6.0%, Mn: greater than 2.0% and at moat 8.0%, sol. Al: 0.003 - 0.015%, with Si (%) - 0.5 x Mn (%) </= 2.0 and the balance being Fe and incidental impurities, The amounts of C, N, and S as impurities are respectively at most 0.005%, at most 0.006%, and at most 0.01%. This steel sheet can be produced from a slab containing up to 0.01% C, up to 0.01% S and 0.001 - 0.010% N by (i) hot rolling the slab to obtain a hot-rolled steel sheet, (ii) cold rolling the hot-rolled steel sheet, as hot-rolled or after being subsequently annealed, one or more times with an intermediate annealing performed between successive stages of cold rolling to prepare a cold-rolled sheet, (iii) causing primary recrystallization by continuous annealing of the cold-rolled sheet, and (iv) finish annealing the continuously annealed steel sheet. The cold rolling may be carried out at a sheet temperature of 70 - 300 DEG C. The finish annealing preferably comprises causing secondary recrystallization by holding the annealed sheet in a temperature range of 825 - 925 DEG C for 7 - 100 hours in a nitrogen-containing atmosphere, and holding the secondary-recrystallized sheet in a temperature range greater than 925 DEG C and up to 1050 DEG C for 4 - 100 hours in a hydrogen atmosphere to carry out purification annealing. |
