JP2011140683A - Non-oriented magnetic steel sheet having excellent magnetic property and blanking workability - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a non-oriented magnetic steel sheet having excellent magnetic properties as an electric equipment iron core material, and further having excellent blanking workability to facilitate forming to an electrical equipment iron core. <P>SOLUTION: The non-oriented magnetic steel sheet has steel components containing, by mass, ≤0.003% C, 1.0 to 3.0% Si, 0.1 to 3.0% Al and 0.1 to 1.0% Mn, and satisfying 0.2≤Al/(Si+Al)≤0.6, and the balance Fe with inevitable impurity elements, and also has a yield ratio of ≥0.6 and a Vickers hardness of ≤200. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a non-oriented electrical steel sheet that is used as an electrical equipment iron core material and has excellent magnetic properties and excellent punchability.

In recent years, in the fields of electrical machinery, especially rotating machines, medium- and small-sized transformers, electrical components, etc. in which non-oriented electrical steel sheets are used as iron core materials, they are representative of global power and energy savings and CO ₂ reduction The demand for higher efficiency and miniaturization is becoming more and more amidst the movement of global environmental conservation. Under such a social environment, naturally, improving the performance of non-oriented electrical steel sheets is an urgent issue.

As is well known, many measures have been taken to improve the performance of non-oriented electrical steel sheets.
In terms of iron loss reduction, in general, from the viewpoint of reducing eddy current loss due to an increase in electrical resistance, a method of increasing the content of Si or Al has been taken. However, this method has a problem that a decrease in magnetic flux density is inevitable.
In addition to simply increasing the content of Si, Al, or the like, high purity steel such as C, S, or N, addition of Ca as described in Patent Document 1, or Patent Document 2 is described. In addition, iron loss has been reduced by detoxifying impurities by chemical treatment such as REM addition. Furthermore, measures on the manufacturing process such as a device for finishing annealing as described in Patent Document 3 have been taken.
On the other hand, with regard to increasing the magnetic flux density as well, measures on the manufacturing process such as hot rolled sheet annealing conditions and cold rolling conditions as described in Patent Document 4 and Sn as described in Patent Document 5 are used. A treatment by improving the primary recrystallization texture by adding an alloying element such as Cu or the like has been performed.

  However, even if the magnetic properties of the non-oriented electrical steel sheet are improved by the above-mentioned measures, it is necessary to consider changes in the magnetic properties during processing when used in electrical equipment as an iron core such as a rotating machine. There is. In particular, when non-oriented electrical steel sheets are punched as core material, the shape of the punched end face and crimped part not only affects the core performance, but also affects the stackability and formability of the core. . That is, unless it is formed into a predetermined shape as an iron core, it cannot exhibit magnetic properties as a material for a non-oriented electrical steel sheet.

Japanese Patent Laid-Open No. 3-126845 JP 2006-124809 A JP-A-61-231120 JP-A-4-325629 Japanese Patent Laid-Open No. 5-140648

  In view of the above, the present invention intends to provide a non-oriented electrical steel sheet having excellent magnetic properties as an electrical equipment core material and excellent in punching workability that facilitates forming into an electrical equipment core. is there.

In the non-oriented electrical steel sheet, the inventors have changed the content of alloying elements added to improve the magnetic properties, and the tensile strength and yield strength, which are representative characteristics of mechanical properties, by changing the magnetic properties. From the viewpoint of whether the characteristics and punching workability can be improved at the same time, we have conducted intensive research.
As a result, the punching workability can be improved by controlling the Si and Al contents as alloying element components and their ratios, as well as the yield ratio (yield strength / tensile strength) indicating the ratio of tensile strength to yield strength. It was clarified that iron loss reduction effect and magnetic flux density improvement effect can be obtained without loss.

  The present invention has been made based on the above findings, and the gist thereof is mass%, C: 0.003% or less, Si: 1.0% or more and 3.0% or less, Al: 0.1% or more. 3.0% or less, Mn: 0.1% or more and 1.0% or less, the content of Al and Si satisfy the relationship of 0.2 ≦ Al / (Si + Al) ≦ 0.6, and the balance Fe And a steel component comprising inevitable impurity elements, a yield ratio expressed by (yield strength / tensile strength) of 0.6 or more, and a Vickers hardness of 200 or less, and magnetic properties and punching It is a non-oriented electrical steel sheet with excellent properties. Still another subject matter is a non-oriented electrical steel sheet excellent in punching workability and magnetic properties after strain relief annealing, which contains P: 0.15% or less in mass% in addition to the steel components described above. Furthermore, in addition to the above steel components, the other gist is one or two of Sn: 0.02% to 0.40% and Cu: 0.1% to 1.0% in mass%. It is a non-oriented electrical steel sheet with excellent punching workability and magnetic properties after strain relief annealing.

  As described above, according to the present invention, it is possible to provide a non-oriented electrical steel sheet that is excellent in both magnetic properties and punchability, and electrical equipment, in particular, a non-oriented electrical steel sheet is used as the iron core material. It can fully meet the demand for higher efficiency and smaller size in the fields of rotating machines, small and medium-sized transformers, electrical components, etc., and its industrial value is extremely high.

Hereinafter, the present invention will be described in detail.
First, the reasons for limiting the steel components of the present invention will be described. In addition,% means the mass%.
C is a harmful component that increases iron loss and causes magnetic aging. Therefore, C is made 0.003% or less.

  As described above, Si is a component that has the effect of reducing iron loss by increasing eddy current loss by increasing electrical resistance, and improves punching workability by increasing the yield ratio. It also has an action to make. In order to achieve these effects, it is necessary to contain 1.0% or more. On the other hand, when the content is increased, as described above, the magnetic flux density is decreased, and the hardness is increased, the punching processability is deteriorated, and also in the manufacturing process itself of the non-oriented electrical steel sheet, Since workability such as cold rolling is reduced and the cost is high, the content is set to 3.0% or less.

  As described above, Al is also a component having an action of reducing iron loss by increasing electric resistance and reducing eddy current loss in the same manner as Si, but its hardness is less increased than Si. In addition, the ratio of the magnetic flux density B50 to the saturation magnetic flux density Bs: B50 / Bs is increased and the magnetic flux density is improved. For this purpose, it is necessary to contain 0.1% or more and to contain Al and Si so that the value of Al / (Si + Al) is 0.2 or more. On the other hand, when the content is increased, the saturation magnetic flux density itself is decreased, leading to a decrease in magnetic flux density, and further a decrease in the yield ratio, which also deteriorates the punching workability. And the value of Al / (Si + Al) is set to 0.6 or less.

Mn has an effect of increasing electrical resistance to reduce eddy current loss, improving primary recrystallization texture to reduce hysteresis loss, and improving magnetic flux density. Furthermore, precipitation of fine sulfides such as MnS harmful to crystal grain growth is suppressed. For these purposes, it is necessary to contain 0.1% or more. However, when the content is increased, the crystal grain growth itself during annealing is lowered and the hysteresis loss is increased.
Although this invention consists of the above component and is based on the steel component which consists of remainder Fe and an unavoidable impurity element, 1 type or 2 types of P, Sn, and Cu can be contained further as follows.

  P is a component that has the effect of increasing the yield ratio and improving the punching workability. However, when its content increases, the hardness increases excessively and the steel sheet becomes brittle, and the non-oriented electrical steel sheet. This causes a problem in the manufacturing process itself and workability at the customer, so the content is set to 0.15% or less.

  Sn develops a primary recrystallized texture of a steel sheet into a desirable (100) or (110) texture for magnetic properties and suppresses a (111) texture that is undesirable for magnetic properties, thereby reducing magnetic flux. It has the effect of improving density and reducing hysteresis loss. Furthermore, it has the effects of suppressing the surface oxidation and nitriding of the steel sheet during annealing and adjusting the grain growth. For these purposes, it is necessary to contain 0.02% or more. On the other hand, even if the content is increased, the action is saturated and, rather, the crystal grain growth itself during annealing is suppressed, so the content is made 0.40% or less.

  Cu, like Sn, has the effect of developing the primary recrystallization texture of the steel sheet to a desirable magnetic property, and in order to exhibit this effect, it is necessary to contain 0.1% or more. However, when the content increases, hot embrittlement is caused and workability in hot rolling or the like in the manufacturing process of the non-oriented electrical steel sheet is lowered, so the content is made 1.0% or less.

In order to make the non-oriented electrical steel sheet composed of the above components excellent in punching workability, the following requirements are provided. The reason for the limitation will be described.
When punching a non-oriented electrical steel sheet into an iron core of a rotating machine, if the end face is drooped during punching, the caulking may be insufficient when laminating the punched steel sheet to the core. Also, the caulking itself becomes difficult. Furthermore, the roundness of the punched steel sheet is impaired, and a problem occurs when the shaft of the rotating machine is inserted. In order to avoid these problems, it is effective to consider the yield ratio (yield strength / tensile strength) as an index for adjusting the elementary process from the start to the completion of plastic processing during punching.

For this purpose, the yield ratio needs to be 0.6 or more. When the yield ratio is less than 0.6, during the punching process of the non-oriented electrical steel sheet, the elongation from the start of plastic deformation to the fracture increases, and it is also affected by the anisotropy of the mechanical properties. It becomes easier and causes end face sag and poor roundness during punching.
If the yield ratio exceeds 0.9, the difference between the yield strength and the tensile strength becomes too small, and plastic deformation at the time of punching may become unstable.

On the other hand, even with non-oriented electrical steel sheets having a yield ratio within the above numerical range, if the hardness is too high, mold wear becomes severe, and even with mold adjustment, the shear plane and fracture surface It becomes difficult to adjust the ratio. For this reason, Vickers hardness needs to be 200 or less.
If the Vickers hardness is less than 100, the flatness after the punching process may be deteriorated.

  For the adjustment of the above yield ratio and Vickers hardness, the selection of chemical components as described above for the reasons for limiting the steel components, and the adjustment of the finish annealing conditions in the manufacturing process of the non-oriented electrical steel sheet, etc. Can be implemented.

Next, examples of the present invention will be described.
Example 1
A non-oriented electrical steel sheet (thickness 0.50 mm) having the components shown in Table 1 was used as an iron core for an industrial machine motor and subjected to processing including punching. The results are shown in Table 2.
In Table 2, no. Although the magnetic characteristics of No. 1 were good, the yield ratio was as low as 0.55 and less than 0.6. Therefore, the punching end face was severely deformed during punching, and caulking defects occurred. No. No. 4, the yield ratio was as high as 0.63, 0.6 or more, and the hardness was also 200 or less, so the punching workability was good, but the Si content was as low as 0.72%, and Since Al / (Si + Al) was as high as 0.69 and exceeded 0.6, the magnetic flux density was reduced. No. 2 and 3, since the alloy component, Al / (Si + Al), yield ratio, and hardness were controlled within the scope of the present invention, both the magnetic properties and the punching workability into the motor core were good, and as an iron core for industrial machine motors. Satisfies the required characteristics.
As can be seen from Table 2, according to the method of the present invention, it is possible to provide a non-oriented electrical steel sheet having excellent magnetic properties and punchability.

(Example 2)
A non-oriented electrical steel sheet (thickness: 0.35 mm) having the components shown in Table 3 was used as an iron core for a refrigerator compressor motor and subjected to processing including punching. The results are shown in Table 4.
In Table 4, no. Although No. 11 had good magnetic properties, its hardness was as high as 211 and exceeded 200, and therefore, die wear was severe during punching and hindered punching. No. In No. 15, the Al content was as high as 3.14%, and Al / (Si + Al) was as high as 0.72 and exceeded 0.6. Further, since the yield ratio was as low as 0.57 and was less than 0.6, the punched end face was severely sag during punching, and caulking defects occurred. No. 12, 13, and 14 were controlled within the scope of the present invention in terms of alloy components, Al / (Si + Al), yield ratio, and hardness, so that both the magnetic properties and the punching workability into the motor core were good. Satisfying the required characteristics.
As can be seen from Table 4, according to the method of the present invention, it is possible to provide a non-oriented electrical steel sheet having excellent magnetic properties and punchability.

Claims (3)

  In mass%, C: 0.003% or less, Si: 1.0% to 3.0%, Al: 0.1% to 3.0%, Mn: 0.1% to 1.0% And the content of Al and Si satisfies the relationship of 0.2 ≦ Al / (Si + Al) ≦ 0.6, has a steel component consisting of the remainder Fe and inevitable impurity elements, and (yield strength / A non-oriented electrical steel sheet excellent in magnetic characteristics and punching workability, characterized in that the yield ratio represented by (tensile strength) is 0.6 or more and the Vickers hardness is 200 or less.   The non-oriented electrical steel sheet excellent in magnetic properties and punching workability according to claim 1, further comprising, as a steel component, P: 0.15% or less by mass%.   The steel component further includes one or two of Sn: 0.02% to 0.40% and Cu: 0.1% to 1.0% in mass%. Item 3. A non-oriented electrical steel sheet excellent in magnetic properties and punching workability according to item 1 or 2.