KR101325369B1 - Non-oriented electromagnetic steel sheet - Google Patents

Abstract

A non-oriented electromagnetic steel sheet contains C: 0.003 mass% or more and 0.05 mass% or less, N: 0.001 mass% or more, 0.01 mass% or less, and Si: 2.8 mass% or more and 3.5 mass% or less. The non-oriented electromagnetic steel sheet further contains at least one selected from the group consisting of Ni: 4.0% by mass or less and Mn: 2.0% by mass or less, in a total amount of 0.5% by mass or more, and further contains a content of Ti in [Ti]% by mass, When content of C is [C] mass% and content of N is [N] mass%, the value R _Ti represented by [Ti] / 4 ([C] + [N]) contains 1 or more and 10 or less. do. Content of Al is 3.0 mass% or less, and content of P is 0.2 mass% or less.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a non-oriented electromagnetic steel sheet,

The present invention relates to a non-directional electromagnetic steel sheet suitable for a rotor of a high-speed rotor.

The non-oriented electromagnetic steel sheet is used, for example, in a rotor of a rotating machine. Generally, the centrifugal force acting on the rotor is proportional to the turning radius, and also proportional to the square of the rotational speed. As a result, a very large stress acts on the rotor of the high-speed rotor. Therefore, it is preferable that the non-oriented electromagnetic steel sheet for rotor has a high tensile strength. That is, it is preferable that the non-oriented electromagnetic steel sheet for a rotor has high tensile strength. Thus, a non-oriented electromagnetic steel sheet for a rotor is required to have a high tensile strength (high tensile strength).

On the other hand, in the non-oriented electromagnetic steel sheet used for the iron core, not limited to the rotor of the rotating machine, it is important that the iron loss is low. Particularly, in a nonoriented electromagnetic steel sheet for a rotor of a high-speed rotor, it is important that the high-frequency iron loss is low. Thus, a low-frequency iron loss is also required for a non-oriented electromagnetic steel sheet for a rotor. That is, high efficiency is also required when the rotor is used at a high frequency.

However, high-tension and low-frequency iron losses are physically incompatible, and it is extremely difficult to make them compatible.

Although the technique which aimed at both these is proposed, there is no thing which can be manufactured easily so far. For example, a technique of obtaining a hot rolled steel sheet having a high Si content and then performing various temperature control has been proposed, but since the Si content is high, cold rolling is very difficult. Moreover, although various temperature control is performed in order to enable cold rolling, since this temperature control is very special, the time, labor, and cost required for it become enormous.

Japanese Patent Application Laid-Open No. 60-238421 Japanese Patent Application Laid-Open No. 61-9520 Japanese Patent Application Laid-Open No. 62-256917 Japanese Patent Application Laid-Open No. 2-8346 Japanese Patent Application Publication No. 2007-186791 Japanese Patent Application Publication No. 2007-186790 Japanese Patent Application Publication No. 2008-240104

An object of the present invention is to provide a non-oriented electromagnetic steel sheet which can be easily produced and which can obtain a high tensile strength and a low-frequency iron loss.

From the viewpoint of obtaining good mechanical properties while suppressing iron loss by suppressing low iron loss due to strengthening of solid solution, strengthening of precipitation, strengthening of workability, strengthening of atomization, strengthening by a transformed structure, etc. in the nonoriented electromagnetic steel sheet, . In addition, the present inventors have repeatedly investigated and analyzed what kind of index is the high frequency iron loss which is important in an actual high speed rotor, in other words, what frequency is important to reduce the iron loss. In addition, easy processing such as cold rolling in the manufacturing process and the avoidance of complicated processing were also considered.

As a result, although it mentions in detail later, content of Si, Mn, Ni, etc. makes it suitable, and the ratio with respect to the total content of C and N of content of Ti makes it suitable, for example, high tensile strength of 900 Mpa or more is obtained. It discovered that high frequency iron loss can be suppressed low. Moreover, it was also found that low iron loss W _10/1000 when the magnetic flux density is _{1.0 T} and the excitation frequency is 1000 Hz is important as the high frequency iron loss. And it coat | covered on the following non-oriented electromagnetic steel plate.

The non-oriented electromagnetic steel sheet which concerns on this invention contains C: 0.003 mass% or more and 0.05 mass% or less, N: 0.001 mass% or more and 0.01 mass% or less, and Si: 2.8 mass% or more and 3.5 mass% or less, Ni: 4.0 mass 0.5 mass% or more is further contained in a total amount of at least 1 sort (s) chosen from the group which consists of% or less and Mn: 2.0 mass% or less, and [Ti] mass%, content of C are [C] mass%, When content of N is made into [N] mass%, the value R _Ti represented by [Ti] / 4 ([C] + [N]) contains 1 or more and 10 or less, and content of Al is 3.0 mass% or less And P content is 0.2 mass% or less, and remainder consists of Fe and an unavoidable impurity. It is characterized by the above-mentioned.

According to the present invention, since the content and the value R _Ti of Si, Mn and Ni are appropriate, high tensile strength and low high frequency iron loss can be obtained. Moreover, since content of Si etc. is suitable, the process in a manufacturing process is easy, and addition of the complex process based on embrittlement etc. can also be avoided.

Hereinafter, the present invention will be described in detail. First, the components of the non-oriented electromagnetic steel sheet according to the present invention will be described.

Si has the effect of reducing iron losses such as high frequency iron loss by increasing the electrical resistance of the non-oriented electromagnetic steel sheet to reduce the eddy current loss. In addition, Si has the effect of increasing the tension of the non-oriented electromagnetic steel sheet by solid solution strengthening. If content of Si is less than 2.8 mass%, these effects become inadequate. On the other hand, when content of Si exceeds 3.5 mass%, difficulty of processing, such as fall of a magnetic flux density, embrittlement, cold rolling, and the like, raises a material cost. Therefore, content of Si is made into 2.8 mass% or more and 3.5 mass% or less.

Al has the effect of reducing iron losses such as high-frequency iron loss by increasing the electrical resistance of the non-oriented electromagnetic steel sheet and reducing the eddy current loss, similarly to Si. Therefore, it may contain for the purpose of further reducing high frequency iron loss. However, when content of Al exceeds 3.0 mass%, the fall of a magnetic flux density, difficulty of processing, such as embrittlement and cold rolling, and raise of material cost are caused. Therefore, the upper limit of content of Al is made into 3.0 mass%. Moreover, when Al content is less than 0.1 mass%, since fine precipitation of AlN is present and iron loss increases, it is preferable that content of Al is 0.1 mass% or more.

Ni and Mn contribute to the improvement of the tension of the non-oriented electromagnetic steel sheet. That is, Ni has a function of increasing the tension by solid solution strengthening, and Mn has a function of increasing the tension by solid solution strengthening and atomization strengthening. In addition, Ni also has an effect of reducing iron loss such as high frequency iron loss by increasing the electrical resistance of the non-oriented electromagnetic steel sheet to reduce the eddy current loss. Ni also contributes to an increase in magnetic flux density accompanied by an increase in saturation magnetic moment of the non-oriented electromagnetic steel sheet. Mn has the effect | action which reduces iron losses, such as a high frequency iron loss, by increasing the electrical resistance of a non-oriented electromagnetic steel plate and reducing eddy current loss. If the total amount of content of Ni and content of Mn is less than 0.5 mass%, these actions will become inadequate and the tensile strength of 900 Mpa or more will not be obtained. On the other hand, when content of Ni exceeds 4.0 mass%, the fall of the magnetic flux density resulting from the fall of a saturation magnetic moment will arise. Moreover, when content of Mn exceeds 2.0 mass%, magnetic flux density will fall and material cost will rise. Accordingly, it is assumed that 4.0 mass% or less of Ni and / or 2.0 mass% or less of Mn is contained in a total amount of 0.5 mass% or more.

P has a function of greatly increasing the tension of the non-directional electromagnetic steel sheet. Therefore, it may be contained for the purpose of improving the tension even further. In order to exhibit this effect, it is preferable that P contains 0.001 mass% or more. However, when content of P exceeds 0.2 mass%, P will segregate to a grain boundary in a manufacturing process, hot rolled steel sheet will embrittle, and subsequent cold rolling will become very difficult. Therefore, the upper limit of content of P is made into 0.2 mass%.

Ti reacts with C and N to produce fine precipitates containing Ti carbonitrides, and has a function of increasing the tension of the non-oriented electromagnetic steel sheet by precipitation strengthening and atomization strengthening. In addition, Ti dissolved in the non-oriented electromagnetic steel sheet has an effect of aligning the crystal orientation of the surface of the non-oriented electromagnetic steel sheet at {111} during cold rolling and finish annealing, for example, to increase the tension of the non-oriented electromagnetic steel sheet. In order to fully exhibit these effects, it is important that both Ti precipitated as Ti carbonitride and Ti dissolved in the non-oriented electromagnetic steel sheet are contained in an appropriate amount.

When content of Ti is [Ti] mass%, content of C is [C] mass%, and content of N is [N] mass%, it is represented by [Ti] / 4 ([C] + [N]). If the value R _Ti is less than 1, the above-described action cannot be sufficiently exhibited. Therefore, the value R _Ti is made 1 or more. If the value R _Ti is 1, theoretically all of Ti is bonded to C and / or N, but in reality some of Ti is not bonded to any of C and N and is included in the non-oriented electromagnetic steel sheet as solid solution Ti. In addition, the value R _Ti is preferably 2 or more, and more preferably 3 or more.

On the other hand, when the value R _Ti exceeds 10, recrystallization hardly occurs and it becomes easy to embrittle. Moreover, with the increase of solid solution Ti, the orientation to {111} may become strong and iron loss may rise. Therefore, the value R _Ti is 10 or less. In addition, the value R _Ti is preferably 9 or less, and more preferably 7 or less.

In addition, in order to make value R _Ti into the said range, content of C shall be 0.003 mass% or more and 0.05 mass% or less, and content of N shall be 0.001 mass% or more and 0.01 mass% or less. Moreover, when content of C exceeds 0.05 mass% or content of N exceeds 0.01 mass%, iron loss characteristic falls remarkably by magnetic aging etc.

In addition, in order to make value R _Ti into the said range, it is preferable that content of Ti is 0.1 mass% or more and 0.3 mass% or less, and it is more preferable that the upper limit of content of Ti is 0.25 mass%.

Moreover, in addition to Ti, Zr, V, Nb, and Mo are mentioned as a metal element which forms carbonitride in a non-oriented electromagnetic steel plate. Among these, precipitation strengthening of Ti carbonitride is remarkable.

The above-described components of the non-oriented electromagnetic steel sheet are, for example, Fe and inevitable impurities. Further, B may be contained for the purpose of avoiding embrittlement of the grain boundaries accompanied by high strength. In this case, the content of B is preferably 0.001% by mass or more. On the other hand, when the content of B exceeds 0.007 mass%, the magnetic flux density is lowered and the brittleness occurs during hot rolling. Therefore, the content of B is preferably 0.007 mass% or less.

Moreover, for the purpose of further improving various magnetic properties, Cu: 0.02 mass% or more and 1.0 mass% or less, Sn: 0.02 mass% or more and 0.5 mass% or less, Sb: 0.02 mass% or more and 0.5 mass% or less, Cr: 0.02 mass% 3.0 mass% or less and / or rare earth metal (REM): 0.001 mass% or more and 0.01 mass% or less may be contained. That is, one or more elements selected from the group consisting of these plural kinds of elements may be contained.

And the tensile strength of the non-oriented electromagnetic steel plate which consists of these components becomes 900 Mpa or more, for example. For this reason, the rotor of the high speed rotor manufactured using this non-oriented electromagnetic steel plate can implement sufficient high speed rotation.

In addition, the high frequency iron loss _W10 / ₁₀₀₀ of the non-oriented electromagnetic steel sheet which _consists of these components becomes 100 W / kg or less, for example. For this reason, the rotor of the high speed rotor manufactured using this non-oriented electromagnetic steel plate can contribute to the high efficiency and miniaturization of a rotor. In other words, it is possible to suppress the loss of energy associated with the conversion from electrical energy to mechanical energy and the heat generation accompanying it. And in order to reduce an eddy current loss and to _make high frequency iron loss _W10 / ₁₀₀₀ into 100 W / kg or less, it is preferable that the thickness of a non-oriented electromagnetic steel plate is 0.30 mm or less.

The present inventors confirmed these effects by the following experiment. First, hot-rolling a slab containing C: 0.017 mass%, Si: 3.12 mass%, Al: 0.65 mass%, Ni: 2.54 mass%, P: 0.02 mass%, N: 0.003 mass%, Ti: 0.18 mass% To obtain a hot rolled steel sheet. The value R _Ti of this hot rolled steel sheet is 2.3. Then, the hot rolled steel sheet was cold rolled to the four types of thickness shown in Table 1, and the cold rolled steel sheet was obtained. Thereafter, the cold rolled steel sheet was subjected to continuous finish annealing at 780 ° C. for 20 seconds to obtain a non-oriented electromagnetic steel sheet. Then, the Epstein sample and the tensile test piece were cut out from the non-oriented electromagnetic steel sheet, and the magnetic and mechanical properties were measured using these. This result is also shown in Table 1. In the following table, "W _15/50 " represents iron loss W _15/50 , "B50" represents magnetic flux density B ₅₀ , and "W _10/1000 " represents iron loss W _10/1000 . "YP" represents a yield point, "TS" represents tensile strength, and "EL" represents an elongation.

As shown in Table 1, in sample No. 1 and No. 2, the tensile strength of 900 MPa or more is obtained, and sample No. 1 and No. 2 are high tensile strength, but the high frequency iron loss W _10/1000 exceeds 100 W / kg. Doing. This is because the thickness of the non-oriented electromagnetic steel sheet exceeds 0.30 mm.

From this, it can be said that the thickness of the non-oriented electromagnetic steel sheet is preferably 0.30 mm or less.

Further, the non-oriented electromagnetic steel sheet according to the present invention can be manufactured, for example, as follows. First, the slab having the above composition is melted and the slab is heated and hot rolled to obtain a hot-rolled steel sheet. Subsequently, this hot rolled steel sheet is cold rolled to obtain a cold rolled steel sheet. Thereafter, finish annealing is performed. Moreover, in order to avoid the fall of the intensity | strength and embrittlement which accompany crystal grain growth, it is preferable not to perform hot-rolled sheet annealing, and it is preferable not to perform the intermediate annealing of cold rolling either. If a hot rolled steel sheet having the above composition is used, the effect of improving the tension and reducing the high frequency iron loss can be obtained without performing hot rolled sheet annealing and intermediate annealing. In addition, bending workability can be improved by omitting the hot rolled sheet annealing. That is, since the non-oriented electromagnetic steel sheet according to the present invention has the above-mentioned composition, it is possible to realize the improvement of the tension and the reduction of the high-frequency iron loss by a relatively simple process.

Example

(First experiment)

First, the slab containing the component shown in Table 2, and remainder is hot-rolled the slab which consists of Fe and an unavoidable impurity, and obtained the hot rolled steel sheet. Subsequently, the hot rolled steel sheet was cold rolled to obtain a cold rolled steel sheet having a thickness of 0.20 mm. Thereafter, the cold rolled steel sheet was subjected to continuous finish annealing at 750 ° C. for 30 seconds to obtain a non-oriented electromagnetic steel sheet.

And the Epstein sample and the tensile test piece were cut out from the non-oriented electromagnetic steel sheet. Then, the magnetic property was measured using the Epstein sample, and the mechanical property was measured using the tensile test piece. The results are shown in Table 3.

As shown in Table 3, in Comparative Examples Nos. 11 and 12, although the high frequency iron loss W _10/1000 was less than 100 W / kg, since the value R _Ti was less than 1, the tensile strength was as low as less than 900 MPa. In particular, in Comparative Example No. 11, since Ti was not contained at all, the tensile strength was remarkably low.

On the other hand, in Examples Nos. 13 and 14, since the value R _Ti and the like are appropriate, high-frequency iron loss W _10/1000 of 100 W / kg or less and tensile strength of 900 MPa or more were obtained. Moreover, yield point was also high compared with the comparative examples No.11 and 12.

(2nd experiment)

First, the slab containing the component shown in Table 4, and remainder of it was hot-rolled the slab which consists of Fe and an unavoidable impurity, and obtained the hot rolled steel plate. Subsequently, the hot rolled steel sheet was cold rolled to obtain a cold rolled steel sheet having a thickness of 0.25 mm. Thereafter, the cold rolled steel sheet was subjected to continuous finish annealing at 775 ° C. for 30 seconds to obtain a non-oriented electromagnetic steel sheet.

And the Epstein sample and the tensile test piece were cut out from the non-oriented electromagnetic steel sheet. Then, the magnetic property was measured using the Epstein sample, and the mechanical property was measured using the tensile test piece. The results are shown in Table 5.

As shown in Table 5, in the comparative examples No. 21 and 22, although the high frequency iron loss _W10 / ₁₀₀₀ was less than 100 W / kg, since the value R _Ti was less than 1, tensile strength was low as less than 900 Mpa. In particular, in Comparative Example No. 21, since Ti was not contained at all, the tensile strength was remarkably low.

On the other hand, in Examples No. 23 and 24, since the value R _Ti or the like is appropriate, high frequency iron loss W _10/1000 of 100 W / kg or less and tensile strength of 900 MPa or more were obtained. Moreover, yield point was also high compared with the comparative examples No.21 and 22.

The present invention can be used, for example, in the electromagnetic steel sheet manufacturing industry and the electromagnetic steel sheet utilization industry.

Claims (8)

C: 0.003 mass% or more and 0.05 mass% or less,
N: 0.001 mass% or more and 0.01 mass% or less
Si: 2.8% by mass or more and 3.5% by mass or less are contained,
4.0 mass% or less of Ni, and 2.0 mass% or less of Mn, in a total amount of 0.5 mass% or more,
In addition, when Ti content is [Ti] mass%, C content is [C] mass%, and N content is [N] mass%, it is [Ti] / 4 ([C] + [N]). The value R _Ti represented contains 1 or more and 10 or less,
Content of Al is 3.0 mass% or less,
Content of P is 0.2 mass% or less,
Non-oriented electromagnetic steel sheet, characterized in that the remaining portion is made of Fe and unavoidable impurities. Content of Ti is 0.1 mass% or more and 0.3 mass% or less, The non-oriented electromagnetic steel sheet of Claim 1 characterized by the above-mentioned. B: 0.001 mass% or more and 0.007 mass% or less, The non-oriented electromagnetic steel sheet of Claim 1 characterized by the above-mentioned. The non-oriented electromagnetic steel sheet according to claim 2, characterized in that B contains 0.001 mass% or more and 0.007 mass% or less. Cu: 0.02 mass% or more and 1.0 mass% or less,
Sn: 0.02 mass% or more and 0.5 mass% or less,
Sb: 0.02 mass% or more and 0.5 mass% or less,
Cr: 0.02 mass% or more and 3.0 mass% or less
Rare earth metal: Non-oriented electromagnetic steel sheet characterized by containing at least 1 sort (s) chosen from the group which consists of 0.001 mass% or more and 0.01 mass% or less. Cu: 0.02 mass% or more and 1.0 mass% or less,
Sn: 0.02 mass% or more and 0.5 mass% or less,
Sb: 0.02 mass% or more and 0.5 mass% or less,
Cr: 0.02 mass% or more and 3.0 mass% or less
Rare earth metal: Non-oriented electromagnetic steel sheet characterized by containing at least 1 sort (s) chosen from the group which consists of 0.001 mass% or more and 0.01 mass% or less. Cu: 0.02 mass% or more and 1.0 mass% or less,
Sn: 0.02 mass% or more and 0.5 mass% or less,
Sb: 0.02 mass% or more and 0.5 mass% or less,
Cr: 0.02 mass% or more and 3.0 mass% or less
Rare earth metal: Non-oriented electromagnetic steel sheet characterized by containing at least 1 sort (s) chosen from the group which consists of 0.001 mass% or more and 0.01 mass% or less. Cu: 0.02 mass% or more and 1.0 mass% or less,
Sn: 0.02 mass% or more and 0.5 mass% or less,
Sb: 0.02 mass% or more and 0.5 mass% or less,
Cr: 0.02 mass% or more and 3.0 mass% or less
Rare earth metal: Non-oriented electromagnetic steel sheet characterized by containing at least 1 sort (s) chosen from the group which consists of 0.001 mass% or more and 0.01 mass% or less.