By optimizing equipment and processing, magnetic domain miniaturization efficiency can be increased, workability can be improved, and processing ability can be increased through same. Provided is a method for miniaturizing the magnetic domains of a directional electric steel plate, the method comprising: a steel plate supporting roll position adjusting step of controlling the vertical direction position of a steel plate while supporting the steel plate progressing along a production line; and a laser emitting step of melting the steel plate by emitting a laser beam to form grooves on the surface of the steel plate, wherein the laser emitting step includes an angle changing step of changing an emitting line angle of the laser beam with respect to a width direction of the steel plate while an optical system emitting the laser beam onto the steel plate is rotated with respect to the steel plate, and a focal distance maintaining step of changing a tilt of the steel plate supporting roll which supports the steel plate according to a change in focal distance of the laser beam in the width direction of the steel plate.

Disclosed is a method for continuous thermal treatment of a steel strip. The strip passes through consecutive thermal treatment chambers, is quickly cooled in at least one of the chambers by spraying liquid onto the strip, or by spraying a fluid made up of gas and liquid or spraying a combination of gas and liquid forming a mist. After quick cooling, a protective metal layer is deposited on the strip by dip coating. The cooling fluid strips iron oxides or other alloy elements contained in the steel to be treated, minimizing oxidation and reducing the oxides on the strip. Spray pressure and distance are chosen to facilitate the stripping property and the mechanical action of the sprayed fluid, reducing the layer of oxides on the strip. The temperature of the strip at the end of the cooling step is the temperature necessary for carrying out the desired treatment cycle.

A hearth roll includes a base roll, a thermally sprayed coating formed on the base roll, and a modified coating formed on the thermally sprayed coating. The modified coating is formed by modifying a part or the whole of a surface of the thermally sprayed coating by melting and solidification of the thermally sprayed coating, by irradiating a part or the whole of the surface of the thermally sprayed coating with an energy beam. The thickness of the modified coating is from 2 to 20 m, and the Vickers hardness HV of the modified coating is from 1.2 to 1.4 times larger than the Vickers hardness HV of the thermally sprayed coating.

Disclosed is a method for continuous thermal treatment of a steel strip. The strip passes through consecutive thermal treatment chambers, is quickly cooled in at least one of the chambers by spraying liquid onto the strip, or by spraying a fluid made up of gas and liquid or spraying a combination of gas and liquid forming a mist. After quick cooling, a protective metal layer is deposited on the strip by dip coating. The cooling fluid strips iron oxides or other alloy elements contained in the steel to be treated, minimizing oxidation and reducing the oxides on the strip. Spray pressure and distance are chosen to facilitate the stripping property and the mechanical action of the sprayed fluid, reducing the layer of oxides on the strip. The temperature of the strip at the end of the cooling step is the temperature necessary for carrying out the desired treatment cycle.

An apparatus for annealing alloy ribbon, the apparatus comprising: an unwinder unwinding an alloy ribbon from a spool of the alloy ribbon; a heating member comprising a first flat surface, on which the alloy ribbon unwound by the unwinder runs while contacting the first flat surface, the heating member heating the alloy ribbon running while contacting the first flat surface through the first flat surface; a cooling member comprising a second flat surface, on which the alloy ribbon heated by the heating member runs while contacting the second flat surface, the cooling member cooling the alloy ribbon running while contacting the second flat surface through the second flat surface; and a winder winding the alloy ribbon cooled by the cooling member.

The steel sheet of the present invention has a steel microstructure containing, in area fraction, martensite: 20% to 100%, ferrite: 0% to 80%, and another metal phase: 5% or less, in which, on a surface of the steel sheet, a ratio of dislocation density in metal phases at a widthwise edge of the steel sheet to dislocation density in the metal phases at a widthwise center of the steel sheet is 100% to 140%, and, at a thicknesswise center of the steel sheet, a ratio of dislocation density in the metal phases at the widthwise edge of the steel sheet to dislocation density in the metal phases at the widthwise center of the steel sheet is 100% to 140%. The maximum amount of warpage of the steel sheet when the steel sheet is sheared to a length of 1 m in a rolling direction is 15 mm or less.

The object of the present invention is to provide an alloy ribbon capable of having excellent adhesiveness between the alloy ribbons when a plurality of the alloy ribbons is stacked; and also, to provide a magnetic core using the alloy ribbon. The present invention is an alloy ribbon comprising metals scattered on at least one surface of the alloy ribbon, in which diameters of the scattered metals are 1 m or more, and the scattered metals include Cu.

Method for thermally treating a scrolling steel strip (5), said method comprising the following steps: heating the strip (5) in a zone for heating with a direct flame (10); temperature homogenisation of the strip (5) in a homogenisation chamber (20) comprising at least one radiant heating tube (25), so as to homogenise the strip (5) in temperature after the passing thereof into the zone for heating with a direct flame (10) of the preceding step; oxidation of the strip (5) in an oxidation chamber (30) with an oxidising atmosphere having an oxygen volume concentration greater than 1%; reduction of the strip (5) in a reduction zone (40).

A hearth roll for a continuous annealing furnace, the hearth roll comprising a thermal spray coating on a surface of the hearth roll, wherein the thermal spray coating comprises main components consisting of a Co-based alloy, a carbide of a transition metal, and a double oxide; and impurities, the double oxide consists of one or two types of a first double oxide consisting of Al and a rare earth element and a second double oxide consisting of a transition metal and a rare earth element, and when the main components are 100 mass %, a content of the Co-based alloy is 25 mass % or more and 50 mass % or less, a content of the carbide is 5 mass % or more and 30 mass % or less, and a content of the double oxide is 20 mass % or more and 45 mass % or less.

Provided is a metal plate to be used for manufacturing a metal mask. In a graph in which an arbitrary position n in a width direction of the metal plate is plotted on a horizontal axis and in which a differential expansion rate En in a unit length L0 in a longitudinal direction is plotted on a vertical axis, a maximum inclination of the differential expansion rate E in a central portion in the width direction is 1.810.sup.3/m or less, and the central portion is a portion that occupies 80% in the width direction excluding both side portions that each occupy 10% in the width direction.