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Non-oriented electrical steel sheet and method of manufacturing the same

Inactive Publication Date: 2016-09-22
NIPPON STEEL CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention provides a method for producing a non-oriented electrical steel sheet with excellent core loss without the need for high purification, slab heating temperature reduction, and hot rolling condition optimization. The method ensures that even fine Cu sulfide is made harmless, and other required properties (magnetic flux density and workability) of a grain-oriented electrical steel sheet are ensured at the same or higher level compared to materials in the related art.

Problems solved by technology

In general, when fine precipitates are present in a steel sheet, grain growth during annealing is retarded, and core loss is deteriorated.
Particularly, Cu which is unavoidably incorporated into the steel sheet generates Cu sulfide, and the fine Cu sulfide inhibits the grain growth of the non-oriented electrical steel sheet.
As a result, core loss is deteriorated.
In addition, the fine Cu sulfide which is present in the steel sheet causes a deterioration in hysteresis loss.
The deterioration in hysteresis loss also causes the deterioration in core loss.
However, in this method, there are problems in productivity, such as an increase in rolling load due to a reduction in slab heating temperature and a difficulty in strict control of the cooling rate.
However, the formation of fine Cu sulfide due to Cu which is incorporated at an unavoidable level cannot be avoided.
Therefore, there is a problem in that magnetic properties are rather deteriorated by the incorporation of Cu.
That is, in the technique of Patent Document 3 in which cooling is performed at a cooling rate of 10° C. / sec to 50° C. / sec, it is difficult to completely eliminate the precipitation of Cu sulfide.
However, in this method, it may not be possible to make Cu sulfide harmless.

Method used

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  • Non-oriented electrical steel sheet and method of manufacturing the same

Examples

Experimental program
Comparison scheme
Effect test

example 1

[0086]An ingot having the components shown in Table 1 was melted in vacuum, and the ingot was heated to 1150° C. and was hot rolled at a hot rolling finish temperature of 875° C. and a coiling temperature of 630° C., thereby producing a hot-rolled steel sheet having a sheet thickness of 2.0 mm. The hot-rolled steel sheet was subjected to hot-rolled sheet annealing, was subjected to pickling, and was cold-rolled at a rolling reduction of 75%, thereby producing a cold-rolled steel sheet having a sheet thickness of 0.50 mm. Heat treatments performed on the test materials and the precipitation states of observed precipitates are shown in Table 2, and the magnetic properties (magnetic flux density and core loss) of each of the obtained steel sheets are shown in Table 3. Evaluation results of core loss evaluated as VG for very good, G for good, F for effective, and B for level in the related art are also shown in Table 3.

[0087]In addition, the evaluation of magnetic properties was perform...

example 2

[0096]An ingot having the chemical components shown in Table 4 was melted in vacuum, and the ingot was heated to 1150° C. and was hot rolled at a hot rolling finish temperature of 850° C., thereby producing a hot-rolled steel sheet having a sheet thickness of 2.3 mm. The hot-rolled steel sheet was subjected to hot-rolled sheet annealing, was subjected to pickling, and was cold-rolled at a rolling reduction of 85%, thereby producing a cold-rolled steel sheet having a sheet thickness of 0.5 mm. Thereafter, final annealing was performed at a holding temperature of T1+50° C. for a holding time of 45 seconds. Thereafter, furnace cooling was performed so that the average cooling rates between T1° C. and T2° C. and between T2° C. and T3° C. were respectively 35° C. / sec and 15° C. / sec. X-ray diffraction results, the precipitation states of precipitates, magnetic properties (magnetic flux density and core loss), brittleness, and overall evaluation results are shown in Table 5.

[0097]Regarding...

example 3

[0099]An ingot having the same components as Steel type No. H23 shown in Table 4 was heated to 1100° C. and was hot-rolled at a finish temperature of 850° C. and a coiling temperature of 630° C., thereby producing a hot-rolled sheet having a sheet thickness of 2.0 mm. The hot-rolled sheet was subjected to final annealing under the conditions shown in Table 5, and was subjected to hot-rolled sheet annealing at 1000° C. for 120 seconds in some examples. Other manufacturing conditions, X-ray diffraction results, the precipitation states of precipitates, and the evaluation results of magnetic properties (magnetic flux density and core loss) are shown in Table 6. Regarding X-ray diffraction, measurement of the magnetic properties, and measurement of the precipitates, the same evaluations as in Example 1 were performed.

TABLE 6FIRST FINALSECOND FINALANNEALINGAVERAGE COOLINGANNEALINGCALCURATEDHOLDINGRATE AFTER FINALHOLDINGTEMPERATURETEMPER-HOLDINGANNEALINGTEMPER-MANUFACTURESTEELT1T2T3ATURET...

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Abstract

A non-oriented electrical steel sheet includes chemical compositions including, in terms of mass %: C: 0.0001% to 0.01%; Si: 0.05% to 7.0%; Mn: 0.01% to 3.0%; Al: 0.0020% to 3.0%; S: 0.0001% to 0.1%; P: 0.0010% to 0.15%; N: 0.0010% to 0.01%; Cu: 0.01% to 5.0%; and a remainder including Fe and impurities, in which I2θ=46.4 which is a diffraction intensity of Cu sulfide having a hexagonal structure shown at 2θ=46.4° and I2θ=32.3 which is a diffraction intensity of Cu sulfide having a cubic structure shown at 2θ=32.3°, which are obtained through a X-ray diffraction of an electrolytic extraction residue, satisfy I2θ=46.4 / I2θ=32.3≦0.5.

Description

[0001]This application is a national stage application of International Application No. PCT / JP2014 / 060164, filed on Apr. 8, 2014, which claims priority to Japanese Patent Application No. 2013-081078, filed on Apr. 9, 2013, each of which is incorporated herein by reference in its entirety.TECHNICAL FIELD OF THE INVENTION[0002]The present invention relates to a non-oriented electrical steel sheet which is used as a core material of an electrical device and a method of manufacturing the same, and more particularly, to a non-oriented electrical steel sheet having excellent core loss and a method of manufacturing the same.RELATED ART[0003]A non-oriented electrical steel sheet is used as a core material of various types of motors for heavy electrical apparatuses, home appliances, and the like. The non-oriented electrical steel sheet is commercially graded according to core loss, and is classified according to the design features of motors or transformers. Recently, from the viewpoint of e...

Claims

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Application Information

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IPC IPC(8): C21D8/12C21D6/00C22C38/00C22C38/06C22C38/02C22C38/04C21D8/02C22C38/16
CPCC22C38/004C21D8/1272C21D8/0263C21D8/0226C21D8/0205C21D6/008C22C38/001C22C38/16C22C38/06C22C38/02C22C38/04C22C38/002C21D6/005C21D8/12C21D2211/004C22C38/60H01F1/16Y02P10/20C22C38/00
Inventor KATAOKA, TAKASHIARITA, YOSHIHIROTAKAHASHI, FUMIAKIKUROSAKI, YOUSUKE
Owner NIPPON STEEL CORP
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