JPS62151511A - Method for decreasing iron loss of grain oriented silicon steel sheet - Google Patents

Abstract

PURPOSE:To considerably decrease an iron loss with good safety by radiating a plasma flame to a grain oriented silicon steel sheet having a prescribed average grain size and magnetic flux density. CONSTITUTION:The plasma flame is radiated to the grain oriented silicon steel sheet having >=3mm average secondary recrystallization grain size and >=1.85T magnetic flux density at 1,000A/m magnetization force. The plasma flame in this stage is preferably radiated linearly in the direction approximately perpendicular to the rolling direction. The angle may be inclined by about 45 deg. and the radiation may not be linear but be spot-like or curvilinear. Since the iron loss of the steel sheet is extremely low according to the above-mentioned method, the energy loss of an electrical apparatus such as transformer for the iron core of which the grain oriented silicon steel sheet is used is considerably decreased.

Description

[Detailed Description of the Invention] (Industrial Application Field) This specification describes the development and research on the effectiveness of plasma flame radiation with regard to reducing iron loss in grain-oriented silicon steel sheets used in iron cores of transformers. The results are described below.

Various attempts have been made for a long time to reduce the iron loss of grain-oriented silicon steel sheets. First, from a metallurgical point of view, these include reducing the deviation of the crystal orientation of secondary recrystallized grains from the (110) [001) orientation, increasing the amount of Si, and reducing the thickness of the product plate. However, although iron loss is certainly reduced by this method, for example, in a steel plate with a thickness of 0.30 mm, the iron loss is l'l17/S. (Iron loss at magnetic flux density 1.7T and frequency 50Hz) is approximately 1.00111/kg0.23
W17/So is approximately 0.90W/k for +++m thick steel plate
g was the limit.

(Prior Art) Japanese Patent Publication No. 57-2252 discloses a method of irradiating with a pulsed laser as a non-metallurgical method. Although this method does reduce iron loss, the initial cost and running cost are unavoidable due to the expensive equipment, the need for safety measures against the laser, and the short lifespan of the laser excitation lamp. sea bream.

(Problems to be solved by the invention) The conventional technology does not have the above-mentioned problems, and improves productivity and
It is an object of the present invention to provide a method that can significantly reduce iron loss by means that are more advantageous in terms of workability, safety, and cost.

(Means for solving the problems) This invention has an average secondary recrystallized grain size of 3 mm or more, a magnetizing force of 10
This is a method for reducing iron loss of a grain-oriented silicon steel sheet, which is characterized by radiating a plasma flame onto the grain-oriented silicon steel sheet having a magnetic flux density of 1.85 T or more at 00 A/m.

As a result of intensive experiments on plasma flame radiation, the inventors found that the average secondary recrystallized grain size (hereinafter referred to as average grain size) is 3 or more, and the magnetic flux density, B, and O at a magnetizing force of 1000 A/m are 1. This invention was completed based on the new discovery that iron loss can be significantly reduced by radiating a plasma flame onto grain-oriented silicon steel sheets of 85T or higher.

The present invention will be explained in detail below based on experimental results.

The average grain size (the average diameter when secondary recrystallized grains are approximated as a circle) is in the range of 1 to 10IIIO, and the magnetizing power is 1000
Magnetic flux density BIG at A/m is 1.80 to 1.96T
A plasma flame was radiated onto a grain-oriented silicon steel plate in the range of .

Here, the plasma flame was generated by applying a voltage between a cathode and an anode mainly composed of tungsten and flowing argon gas, and was emitted from a nozzle with a nozzle diameter of 0.1 to 2.0+++[Il]. The radiation was linearly radiated almost perpendicularly to the rolling direction of the steel plate, and the interval between the radiations was set at 5 to 15 mm. The larger the nozzle hole diameter, the larger the output current can flow, but IA
It was varied in the range of ~300A.

The thicknesses of the steel plates used were 0.30 mm, 0.27 mm, and 0.23 mm, and the magnetic properties before and after plasma flame radiation were measured using a single plate magnetometer.

FIG. 1 shows the difference in iron loss (ltL7zso) before and after plasma flame irradiation with respect to BNI and average particle size. The ○ mark indicates that W, , □5o is 0y03W/ due to plasma flame radiation.
However, the maximum iron loss improvement due to plasma flame radiation was 0.2511i/kg.

As is clear from the figure, a significant reduction in iron loss was observed by irradiating plasma flame on steel plates with an average grain size of 3 mm or more and a B1° value of 1.857 or more.

The above effects can be seen when the average particle size is 3 mm or more and the 81° value is 1 or 8.
If it was 5T or more, it was recognized regardless of the presence or absence of an insulating coating and the surface shape of the steel plate.

The grain-oriented silicon steel sheet used in this invention can be used regardless of the manufacturing method as long as it satisfies the above average grain size and Blo value conditions, but generally it acts as an inhibitor during secondary recrystallization. (MnS.

A hot-rolled steel plate containing MnSe, AIN, etc. is cold rolled once or twice including intermediate annealing to achieve the product thickness, then subjected to decarburization annealing and final finish annealing for secondary recrystallization. Then, if necessary, an insulating coating can be applied afterwards.

Normally, finish-burning pure steel sheets are covered with a forsterite film that is produced during finish annealing, but plasma flame radiation can be applied even from above this forsterite to a state in which there is no forsterite, and furthermore, the phosphate that is usually overcoated on the forsterite. It may also be applied over a coating containing as the main component.

Further, coating may be performed after plasma irradiation.

It is desirable that the plasma flame be radiated linearly in a direction substantially perpendicular to the rolling direction, but this angle may be inclined up to about 45°. Moreover, the shape may be a dotted line or a curved line instead of a straight line. When radiating in a line, the line spacing is 2~
Approximately 30 mm is desirable.

The plasma flame is non-transferable and easy to radiate, and the nozzle hole diameter is preferably 2 carp diameter or less.

Plasma flame radiation can be either non-transfer type or transfer type, but the non-transfer type is easier to emit. The voltage and current for generating plasma flame are not particularly regulated, but must be determined taking into consideration the stable generation of plasma flame and the lifespan of the nozzle. Gas for plasma generation is Ar, N21
Inert and non-oxidizing gases such as 82 and mixtures thereof are preferred, but oxidizing gases and mixtures thereof may also be used.

(Function) The reason why iron loss is reduced by this invention is presumed to be that the part where the plasma flame is radiated becomes magnetically hard, subdividing the magnetic domain and reducing eddy current loss.

(Example) Finish annealed 0 with the average grain size and B+O value shown in Table 1,
A plasma flame was radiated onto a grain-oriented silicon steel plate having a thickness of 23n+m from a plasma torch having a nozzle hole diameter of 0.15mmφ. Argon was used as the gas, the voltage was 30V, and the current was 7A.

The radiation is emitted linearly in the direction perpendicular to the rolling direction of the steel plate, the radiation interval is 8.5 mm, and the scanning speed of the torch is 200 mm/s.
And so. As shown in Table 1, the iron loss W+7/So before and after radiation, a significant reduction in iron loss was observed in the adapted example according to the present invention.

(Effects of the invention) This invention makes it possible to significantly reduce the iron loss of grain-oriented silicon steel sheets, and significantly reduces the energy loss of electrical equipment such as transformers that use grain-oriented silicon steel sheets for their iron cores. .

[Brief explanation of drawings]

Figure 1 shows the effect of plasma flame radiation on the average grain size of the irradiated steel plate, 8. This is shown for the value. Eaves〔Patent applicant: Kawasaki Steel Co., Ltd.
Wr'l/so 力翫°゛子发力゛Inferior Ibishi f: Mo's t8
0 /, 85 1QOf, Q5
2.00B2. Value (T)

Claims (1)

[Claims] 1. Average secondary recrystallized grain size 3 mm or more, magnetizing power 1000 A
1. A method for reducing iron loss in a grain-oriented silicon steel sheet, the method comprising radiating a plasma flame onto the grain-oriented silicon steel sheet having a magnetic flux density of 1.85 T or higher at a temperature of 1.85 T or more.