Provided is a steel sheet comprising a sheet thickness center part and a first surface layer softened part and a second surface layer softened part respectively arranged at two sides of the sheet thickness center part, wherein the first surface layer softened part and second surface layer softened part have 10 μm or more average thicknesses and have average Vickers hardnesses of 0.90 time or less of the average Vickers hardness of a sheet thickness ½ position, and the first surface layer softened part has an average Vickers hardness of 1.05 times or more the average Vickers hardness of the second surface layer softened part.

Process to decarburize steel are described. A process can include contacting carbon dioxide with molten steel in an electric arc furnace, a ladle furnace, or a vacuum degassing unit, or a combination thereof.

Process to decarburize steel are described. A process can include contacting carbon dioxide with molten steel in an electric arc furnace, a ladle furnace, or a vacuum degassing unit, or a combination thereof.

A grain-oriented electrical steel sheet includes a groove formed on a surface and a solidified alloy layer formed under the groove, wherein the solidified alloy layer includes particles of a certain average diameter.

A grain-oriented electrical steel sheet includes a groove formed on a surface and a solidified alloy layer formed under the groove, wherein the solidified alloy layer includes particles of a certain average diameter.

Provided is a method of manufacturing a grain-oriented electrical steel sheet with which a grain-oriented electrical steel sheet with excellent magnetic properties and little variation in iron loss in the longitudinal direction of a coil can be stably manufactured. The method includes subjecting a steel slab to hot-rolling and optionally to annealing, then performing cold rolling once or twice or more to obtain a cold-rolled sheet with a final sheet thickness, and then subjecting the cold-rolled sheet to decarburization annealing and then secondary recrystallization annealing, where immediately before final cold rolling, a steel sheet is heated at a heating rate of 100° C./s or more to a heating temperature of 100° C. or higher and 350° C. or lower, and a time from when the steel sheet reaches the heating temperature to when it is bitten in a first pass of final cold rolling is set to within 5 seconds.

Provided is a method of manufacturing a grain-oriented electrical steel sheet with which a grain-oriented electrical steel sheet with excellent magnetic properties and little variation in iron loss in the longitudinal direction of a coil can be stably manufactured. The method includes subjecting a steel slab to hot-rolling and optionally to annealing, then performing cold rolling once or twice or more to obtain a cold-rolled sheet with a final sheet thickness, and then subjecting the cold-rolled sheet to decarburization annealing and then secondary recrystallization annealing, where immediately before final cold rolling, a steel sheet is heated at a heating rate of 100° C./s or more to a heating temperature of 100° C. or higher and 350° C. or lower, and a time from when the steel sheet reaches the heating temperature to when it is bitten in a first pass of final cold rolling is set to within 5 seconds.

A non-oriented electrical steel sheet with an average magnetostriction λ.sub.p-p at 400 Hz and 1.0 T of not more than 4.5×10.sup.−6, and area ratio of recrystallized grains at a section in rolling direction of steel sheet of 40 to 95% and an average grain size of 10 to 40 μm is obtained by subjecting a steel slab containing, in mass %, C: not more than 0.005%, Si: 2.8 to 6.5%, Mn: 0.05 to 2.0%, Al: not more than 3.0%, P: not more than 0.20%, S: not more than 0.005%, N: not more than 0.005%, Ti: not more than 0.003%, V: not more than 0.005% and Nb: not more than 0.005% and satisfying Si-2Al—Mn≥0 to hot rolling, hot-band annealing, cold rolling and finish annealing under adequate cold rolling and finish annealing conditions, and a motor core is manufactured by such a steel sheet.

A method for refining magnetic domains of a grain-oriented electrical steel sheet according to an exemplary embodiment of the present invention includes: a step of preparing a grain-oriented electrical steel sheet; and a step of forming a groove by irradiating a quasi-continuous laser beam of which a duty is from 98.0 to 99.9% on a surface of the grain-oriented electrical steel sheet.

A method for refining magnetic domains of a grain-oriented electrical steel sheet according to an exemplary embodiment of the present invention includes: a step of preparing a grain-oriented electrical steel sheet; and a step of forming a groove by irradiating a quasi-continuous laser beam of which a duty is from 98.0 to 99.9% on a surface of the grain-oriented electrical steel sheet.