The method includes slab-heating a steel slab to a temperature of higher than a ?-phase precipitation temperature and 1380? C. or lower, subjecting the steel slab to rough rolling including at least two passes of rolling at a predetermined temperature with an introduced sheet thickness true strain ?.sub.t of 0.50 or more and to finish rolling with a rolling finish temperature of 900? C. or higher to obtain a hot-rolled sheet, cooling the hot-rolled sheet for 1 second or longer at a cooling rate of 70? C./s or higher within 2 seconds after finish rolling, coiling the sheet at a coiling temperature of 600? C. or lower, performing hot-rolled sheet annealing for soaking at a predetermined soaking temperature, and then performing cold rolling, primary recrystallization annealing, and secondary recrystallization annealing.

In this non-oriented electrical steel sheet, an area proportion of crystal grains having a crystal grain size of less than 200 ?m is 10% or lower when a boundary with a crystal orientation difference of 2? or more and less than 15? is regarded as a crystal grain boundary in a cross section parallel to a steel sheet surface.

A method for manufacturing a thin strip component, including a processing step of processing an amorphous thin strip member into a dimension shape larger than a target shape, and a heat treating step of heat treating and contracting the amorphous thin strip member processed in the processing step to form the amorphous thin strip member into a thin strip component of the target shape. A thin strip component which is a magnetic laminate in which a plurality of plate-shaped thin strip component members of the same shape are laminated, and has a recess over an entire side surface of the magnetic laminate is used. A motor including the thin strip component, a plurality of coils disposed on the thin strip component, and a rotor disposed between the plurality of coils is used.

A steel sheet comprising, by mass %, C: 0.05 to 0.40%, Si: 0.2 to 3.0%, and Mn: 0.1 to 5.0%, wherein a surface layer of the steel sheet contains granular oxides, an average grain size of the granular oxides is 300 nm or less, a number density of granular oxides is 4.0/?m.sup.2 or more, the steel sheet comprises an SiMn depleted layer having a thickness of 3.0 ?m or more from the surface of the steel sheet, and Si and Mn contents of the SiMn depleted layer not containing oxides at the ? position of the thickness are respectively less than 10% of the Si and Mn contents at the sheet thickness center part of the steel sheet, and a plated steel sheet using the same are provided.

The method includes slab-heating a steel slab to a temperature of higher than a ?-phase precipitation temperature and 1380? C. or lower, subjecting the steel slab to rough rolling including at least two passes of rolling at a predetermined temperature with an introduced sheet thickness true strain ?.sub.t of 0.50 or more and to finish rolling with a rolling finish temperature of 900? C. or higher to obtain a hot-rolled sheet, cooling the hot-rolled sheet for 1 second or longer at a cooling rate of 70? C./s or higher within 2 seconds after finish rolling, coiling the sheet at a coiling temperature of 600? C. or lower, performing hot-rolled sheet annealing for soaking at a predetermined soaking temperature, and then performing cold rolling, primary recrystallization annealing, and secondary recrystallization annealing.

Provided is a method and device for refining a magnetic domain of a grain-oriented electrical steel plate. The magnetic domain refining method of a grain-oriented electrical steel plate for stable permanent magnetic domain refining processing even if a steel plate is transferred at high speed of 2 m/s or more includes zigzag controlling for straightly transferring the steel plate without being inclined in right and left directions along a production line center, tension controlling for applying tension to the steel plate to maintain the steel plate in a flat state, steel plate support roll position adjusting for controlling a predetermined position of the steel plate in up and down directions while supporting the steel plate, and laser irradiating for irradiating a laser beam to melt the steel plate to form a groove in a surface of the steel plate.

A method for producing a grain-oriented electrical steel sheet includes steps of heating a steel slab having a specified ingredient composition to a temperature of 1300 or lower; subjecting the slab to hot rolling and then one cold rolling or two or more cold rolling with intermediate annealing between each rolling to obtain a cold-rolled sheet with a final sheet thickness; performing primary recrystallization annealing which also serves as decarburization annealing; applying an annealing separator; and subjecting the steel sheet to finishing annealing. In this method, after soaking in the annealing step preceding the cold rolling for achieving the final sheet thickness, the steel sheet is cooled from 800 to 400? C. at an average cooling rate of 15? C./s or more and subsequently subjected to low-temperature heat treatment comprising holding the sheet at a temperature in a range of 60 to 100? C. for 30 to 600 seconds.

When producing a non-oriented electrical steel sheet by subjecting a slab containing a predetermined composition to hot rolling, hot-band annealing, cold rolling, and finishing annealing in a continuous annealing furnace, the following conditions are used: a maximum reached temperature in the finishing annealing is set to be lower than 900? C.; an average cooling rate from a temperature to 500? C. in a cooling process of the finishing annealing is set to 40? C./s or higher; a parameter ?/t defined from a plastic elongation ratio ? (%) in a rolling direction between before and after the finishing annealing and a soaking time t (s) in the finishing annealing is set to 0.10 or higher; an average ferrite grain size is 50 ?m or larger; and compressive residual stresses ?.sub.s and ?.sub.c in a sheet width direction at a steel sheet surface and a sheet-thickness center part, respectively, are both 2.0 MPa or higher.

Provided is a grain-oriented electrical steel sheet having an excellent noise property in an actual transformer. Magnetostrictive properties of the grain-oriented electrical steel sheet are set such that the number of acceleration/deceleration points that are present in the magnetostriction velocity level d?/dt in one period of magnetostrictive vibration is 4 and the magnitude of velocity level change between adjacent velocity change points in an acceleration zone or deceleration zone of magnetostrictive vibration is 3.0?10.sup.?4 sec.sup.?1 or less.

Provided are a grain-oriented electrical steel sheet with low iron loss even when including at least one grain boundary segregation element among Sb, Sn, Mo, Cu, and P, and a method for manufacturing the same. In our method, Pr is controlled to satisfy Pr0.075T+18, where T>10, 5<Pr, T (hr) is the time required after final annealing to reduce the temperature of a secondary recrystallized sheet from 800 C. to 400 C., and Pr (MPa) is the line tension on the secondary recrystallized sheet during flattening annealing. As a result, a grain-oriented electrical steel sheet in which iron loss is low and a dislocation density near crystal grain boundaries of the steel substrate is 1.010.sup.13 m.sup.2 or less can be obtained even when the grain-oriented electrical steel sheet contains at least one of Sb, Sn, Mo, Cu, and P.