Abstract: A non-oriented electrical steel sheet containing: in mass %, C: 0.005% or less; Si: 0.1% to 2.0%; Mn: 0.05% to 0.6%; P: 0.100% or less; and Al: 0.5% or less, in which 10 pieces/?m3 or less in number density of non-magnetic precipitate AlN having an average diameter of 10 nm to 200 nm are contained, and an average magnetic flux density B50 in a rolling direction and in a direction perpendicular to rolling is 1.75 T or more. This non-oriented electrical steel sheet can be manufactured by two methods of a method of performing hot rolling annealing at a temperature of 750° C. to an Ac1 transformation point and a method of setting a coil winding temperature to 780° C. or higher and performing self annealing.

Abstract: A silicon steel sheet (1) containing Si is cold-rolled. Next, a decarburization annealing (3) of the silicon steel sheet (1) is performed so as to cause a primary recrystallization. Next, the silicon steel sheet (1) is coiled so as to obtain a steel sheet coil (31). Next, an annealing (6) of the steel sheet coil (31) is performed through batch processing so as to cause a secondary recrystallization. Next, the steel sheet coil (31) is uncoiled and flattened. Between the cold-rolling and the obtaining the steel sheet coil (31), a laser beam is irradiated a plurality of times at predetermined intervals on a surface of the silicon steel sheet (1) from one end to the other end of the silicon steel sheet (1) along a sheet width direction (2). When the secondary recrystallization is caused, grain boundaries passing from a front surface to a rear surface of the silicon steel sheet (1) along paths of the laser beams are generated.

Abstract: In a method of manufacturing a grain-oriented electrical steel sheet including a nitriding treatment (step S7) and adopting so-called “low-temperature slab heating”, the finish temperature of finish rolling in hot rolling (step S2) is set to 950° C. or below, the cooling is started within 2 seconds after completion of the finish rolling, and a steel strip is coiled at 700° C. or below. The cooling rate over the duration from the end of finish rolling to the start of coiling is set to 10° C./sec or above. In annealing (step S3) of the hot-rolled steel strip, the heating rate in the temperature range from 800° C. to 1000° C. is set to 5° C./sec or above.

Abstract: When contents of Ti, V, Zr, Nb, and C (mass %) are represented as [Ti], [V], [Zr], [Nb], and [C] respectively, a value of a parameter Q represented by “Q=([Ti]/48+[V]/51+[Zr]/91+[Nb]/93)/([C]/12)” is not less than 0.9 nor more than 1.1. A matrix of a metal structure is a ferrite phase, and the metal structure does not include a non-recrystallized structure. An average grain size of ferrite grains constituting the ferrite phase is not less than 10 ?m nor more than 200 ?m. A precipitate containing at least one selected from the group consisting of Ti, V, Zr, and Nb exists with a density of 10 ?m?3 or more in the ferrite grain. An average grain size of the precipitate is not less than 0.002 ?m nor more than 0.2 ?m.

Abstract: A value of a parameter Q represented by “Q=([Ti]/48+[V]/51+[Zr]/91+[Nb]/93)/([C]/12)” is not less than 0.9 nor more than 1.1, when contents of Ti, V, Zr, Nb, and C (mass %) are represented as [Ti], [V], [Zr], [Nb], and [C] respectively. A matrix of a metal structure is a ferrite phase, and the metal structure does not contain a non-recrystallized structure. An average grain size of ferrite grains constituting the ferrite phase is not less than 30 ?m nor more than 200 ?m. A precipitate containing at least one selected from the group consisting of Ti, V, Zr, and Nb exists with a density of 1 particle/?m3 or more in the ferrite grain. An average grain size of the precipitate is not less than 0.002 ?m nor more than 0.2 ?m.

Abstract: A grain-oriented electrical steel sheet being a grain-oriented electrical steel sheet containing Si of 0.8 mass % to 7 mass %, Mn of 0.05 mass % to 1 mass %, B of 0.0005 mass % to 0.0080 mass %, each content of Al, C, N, S, and Se of 0.005 mass % or less, and a balance being composed of Fe and inevitable impurities and having a glass coating film made of composite oxide mainly composed of forsterite on the steel sheet surface, in which when glow discharge optical emission spectrometry (GDS) to the surface of a secondary coating film formed on the surface of the glass coating film under a predetermined condition is performed, a peak, of B, in emission intensity having a peak position in emission intensity different from a peak position, of Mg, in emission intensity is obtained and the peak position, of B, in emission intensity from the steel sheet surface is deeper than the peak position, of Mg, in emission intensity.

Abstract: A silicon steel sheet (1) containing Si is cold-rolled. Next, a decarburization annealing (3) of the silicon steel sheet (1) is performed so as to cause a primary recrystallization. Next, the silicon steel sheet (1) is coiled so as to obtain a steel sheet coil (31). Next, an annealing (6) of the steel sheet coil (31) is performed through batch processing so as to cause a secondary recrystallization. Next, the steel sheet coil (31) is uncoiled and flattened. Between the cold-rolling and the obtaining the steel sheet coil (31), a laser beam is irradiated a plurality of times at predetermined intervals on a surface of the silicon steel sheet (1) from one end to the other end of the silicon steel sheet (1) along a sheet width direction (2). When the secondary recrystallization is caused, grain boundaries passing from a front surface to a rear surface of the silicon steel sheet (1) along paths of the laser beams are generated.

Abstract: A nitriding treatment (Step S6) in which an N content of a decarburization-annealed steel strip is increased is performed between start of a decarburization annealing (Step S4) and occurrence of secondary recrystallization in a finish annealing (Step S5). In hot rolling (Step S1), a silicon steel material is held in a temperature range between 1000° C. and 800° C. for 300 seconds or longer, and then finish rolling is performed.

Abstract: In a method of manufacturing a grain-oriented electrical steel sheet including a nitriding treatment (step S7) and adopting so-called “low-temperature slab heating”, the finish temperature of finish rolling in hot rolling (step S2) is set to 950° C. or below, the cooling is started within 2 seconds after completion of the finish rolling, and a steel strip is coiled at 700° C. or below. The cooling rate over the duration from the end of finish rolling to the start of coiling is set to 10° C./sec or above. In annealing (step S3) of the hot-rolled steel strip, the heating rate in the temperature range from 800° C. to 1000° C. is set to 5° C./sec or above.

Abstract: A silicon steel material is heated in a predetermined temperature range according to contents of B, N, Mn, S, and Se (step S1), and is subjected to hot rolling (step S2). Further, a finish temperature Tf of finish rolling in the hot rolling is performed in a predetermined temperature range according to the content of B. Through these treatments, a certain amount of BN is made to precipitate compositely on MnS and/or MnSe.

Abstract: A predetermined steel containing Te: 0.0005 mass % to 0.0050 mass % is heated to 1320° C. or lower to be subjected to hot rolling, and is subjected to annealing, cold rolling, decarburization annealing, and nitridation annealing, and thereby a decarburized nitrided steel sheet is obtained. Further, an annealing separating agent is applied on the surface of the decarburized nitrided steel sheet and finish annealing is performed, and thereby a glass coating film is formed. The N content of the decarburized nitrided steel sheet is set to 0.0150 mass % to 0.0250 mass % and the relationship of 2×[Te]+[N]?0.0300 mass % is set to be established. Note that [Te] represents the Te content and [N] represents the N content.

Abstract: Hot rolling is performed on a steel with a predetermined composition containing Ti: 0.0020 mass % to 0.010 mass % and/or Cu: 0.010 mass % to 0.50 mass % to obtain a hot-rolled steel sheet. Annealing is performed on the hot-rolled steel sheet to obtain an annealed steel sheet. Cold rolling is performed on the annealed steel sheet to obtain a cold-rolled steel sheet. Decarburization annealing and nitridation annealing are performed on the cold-rolled steel sheet to obtain a decarburized nitrided steel sheet. Then, finish annealing is performed on the decarburized nitrided steel sheet. When obtaining the decarburized nitrided steel sheet, heating on the cold-rolled steel sheet is started in a decarburizing and nitriding atmosphere, then first annealing is performed at a first temperature within a predetermined range, and then second annealing is performed at a second temperature within a predetermined range.

Abstract: Hot rolling is performed on a steel with a predetermined composition containing Ti: 0.0020 mass % to 0.010 mass % and/or Cu: 0.010 mass % to 0.50 mass % to obtain a hot-rolled steel sheet. Annealing is performed on the hot-rolled steel sheet to obtain an annealed steel sheet. Cold rolling is performed on the annealed steel sheet to obtain a cold-rolled steel sheet. Decarburization annealing is performed on the cold-rolled steel sheet at a temperature of 800° C. to 950° C. to obtain a decarburization annealed steel sheet. Then, nitridation treatment is performed on the decarburization annealed steel sheet at 700° C. to 850° C. to obtain a nitrided steel sheet. Finish annealing is performed on the nitrided steel sheet.

Abstract: A slab with a predetermined composition is heated at 1280° C. to 1390° C. to make a substance functioning as an inhibitor to be solid-solved (step S1). Next, the slab is hot-rolled to obtain a steel strip (step S2). The steel strip is annealed to form a primary inhibitor in the steel strip (step S3). Next, the steel strip is cold-rolled once or more (step S4). Next, the steel strip is annealed to perform decarburization and to cause primary recrystallization (step S5). Next, nitriding treatment is performed on the steel strip in a mixed gas of hydrogen, nitrogen and ammonia under a state where the steel strip runs, to form a secondary inhibitor in the steel strip (step S6). Next, the steel strip is annealed to induce secondary recrystallization (step S7).

Abstract: A surface temperature of a slab is decreased down to 600° C. or lower between start of continuous casting (step S2) and start of slab reheating (step S3). The surface temperature of the slab is held at 150° C. or higher between the start of the continuous casting (step s2) and the start of the slab reheating (step S3). The surface temperature of the slab in the slab reheating (step S3) is set to not lower than 1080° C. and not higher than 1200° C.

Abstract: A nitriding treatment (Step S6) in which an N content of a decarburization-annealed steel strip is increased is performed between start of a decarburization annealing (Step S4) and occurrence of secondary recrystallization in a finish annealing (Step S5). In hot rolling (Step S1), a silicon steel material is held in a temperature range between 1000° C. and 800° C. for 300 seconds or longer, and then finish rolling is performed.

Abstract: A silicon steel material is heated in a predetermined temperature range according to contents of B, N, Mn, S, and Se (step S1), and is subjected to hot rolling (step S2). Further, a finish temperature Tf of finish rolling in the hot rolling is performed in a predetermined temperature range according to the content of B. Through these treatments, a certain amount of BN is made to precipitate compositely on MnS and/or MnSe.

Abstract: A surface temperature of a slab is decreased down to 600° C. or lower between start of continuous casting (step S2) and start of slab reheating (step S3). The surface temperature of the slab is held at 150° C. or higher between the start of the continuous casting (step s2) and the start of the slab reheating (step S3). The surface temperature of the slab in the slab reheating (step S3) is set to not lower than 1080° C. and not higher than 1200° C.

Abstract: In a production of grain-oriented electrical steel sheet that is heated at a temperature of not higher than 1350° C., (a) the hot-rolled sheet is heated to a prescribed temperature of 1000° C. to 1150° C., and after recrystallization is annealed for a required time at a lower temperature of 850° C. to 1100° C., or (b) in the hot-rolled sheet annealing process decarburization is conducted to adjust the difference in the amount of carbon before and after decarburization to 0.002 to 0.02 mass %. In the temperature elevation process used in the decarburization annealing of the steel sheet, heating is conducted in the temperature range of 550° C. to 720° C. at a heating rate of at least 40° C./s, preferably 75 to 125° C./s, utilizing induction heating for the rapid heating used in the temperature elevation process in decarburization annealing.

Abstract: The present invention provides a method of production of grain-oriented electrical steel sheet comprising making a slab heating temperature 1280° C. or less, annealing hot rolled sheet by (a) a process of heating it to a predetermined temperature of 1000 to 1150° C. to cause recrystallization, then annealing by a temperature lower than that of 850 to 1100° C. or by (b) decarburizing in annealing the hot rolled sheet so that a difference in amounts of carbon of the steel sheet before and after annealing the hot rolled sheet becomes 0.002 to 0.02 mass % and performing the heating in the temperature elevation process of the decarburization annealing under conditions of a heating rate of 40° C. or more, preferably 75 to 125° C./s while the temperature of the steel sheet is in a range from 550° C. to 720° C. and utilizing induction heating for rapid heating in the temperature elevation process of decarburization annealing.