Method for heat treating magnetic wire includes a wire supply unit, a wire property measuring unit, a wire tensile force measuring unit, a heat treatment unit, and a wire winding unit. The wire supply unit includes a supply bobbin, a supply rotary part, a wire reel, and a tension roller. The wire property measuring unit includes a size measuring device, an after measurement capstan, and a wire reel and measures a size of the wire prior to the heat treatment. The wire tensile force measuring unit includes a tensile force measuring device, a tension roller, and a wire reel. The wire heat treatment unit includes a heat treatment furnace, a temperature measuring device, an after heat treatment capstan, and a wire reel. The wire winding unit includes a winding bobbin, a winding rotary part that rotates the winding bobbin, a tension roller, and a wire reel.

A method for forming a film on a surface of a steel sheet includes applying a treatment solution for forming a film containing a fibrous material to the surface of the steel sheet by using a coater under a condition in which a difference between a speed of the steel sheet and a speed of an applicator of the coater is 1.0 m/min or more, inclining the surface of the steel sheet, to which the treatment solution for forming a film has been applied, at an angle of 10? or more with respect to a horizontal plane until drying is started, and thereafter drying the steel sheet.

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.

Apparatus for heat treating magnetic wire includes a wire supply unit, a wire property measuring unit, a wire tensile force measuring unit, a heat treatment unit, and a wire winding unit. The wire supply unit includes a supply bobbin, a supply rotary part, a wire reel, and a tension roller. The wire property measuring unit includes a size measuring device, an after measurement capstan, and a wire reel and measures a size of the wire prior to the heat treatment. The wire tensile force measuring unit includes a tensile force measuring device, a tension roller, and a wire reel. The wire heat treatment unit includes a heat treatment furnace, a temperature measuring device, an after heat treatment capstan, and a wire reel. The wire winding unit includes a winding bobbin, a winding rotary part that rotates the winding bobbin, a tension roller, and a wire reel.

Apparatus for heat treating magnetic wire includes a wire supply unit, a wire property measuring unit, a wire tensile force measuring unit, a heat treatment unit, and a wire winding unit. The wire supply unit includes a supply bobbin, a supply rotary part, a wire reel, and a tension roller. The wire property measuring unit includes a size measuring device, an after measurement capstan, and a wire reel and measures a size of the wire prior to the heat treatment. The wire tensile force measuring unit includes a tensile force measuring device, a tension roller, and a wire reel. The wire heat treatment unit includes a heat treatment furnace, a temperature measuring device, an after heat treatment capstan, and a wire reel. The wire winding unit includes a winding bobbin, a winding rotary part that rotates the winding bobbin, a tension roller, and a wire reel.

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.

A tension annealing treatment consisting of a furnace and the operation method can improve magnetic properties of magnetic wire with a diameter of under 20 m and achieve continuous operation without wire breakage by controlling the temperature and tensile stress in the furnace with designated values accurately by means of a wire diameter measuring device, tension measuring device, plural capstans and tension rollers between plural capstans installed in the furnace. The interval between a wire supply bobbin and a wire winding up bobbin is divided into serval parts which are controlled to have same conveyance speed and tensile stress to dissolve the deference of each other by controlling the rotary speed of capstans and the tension loaded by tension rollers.