JP4292805B2 - Method for producing non-oriented electrical steel sheet with excellent magnetic properties - Google Patents

Description

【００３１】
表１より、鋼板成分および冷間圧延前粒径を本発明の範囲に制御した本発明鋼では、異方性が低減され、仕上焼鈍後の磁気特性が優れていることがわかる。特に結晶粒径５００μｍ超の領域で優れた特性が得られている。
【００３２】
一方、比較鋼では、鉄損、磁束密度、異方性のいずれか一つ以上が劣っている。
【００３３】
【発明の効果】
以上述べたように、本発明によれば、鉄損が低く磁束密度の高い鋼板を得ることが出来、本発明の鋼板を使用することにより例えば高効率誘導モータの高効率化が達成できる。さらに本発明の鋼板は、誘導モータ以外のモータの効率向上にも効果的である。
【図面の簡単な説明】
【図１】冷間圧延前粒径と磁束密度、異方性との関係を示す図。
【図２】Ｓｎ量と異方性との関係を示す図。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method of manufacturing an electromagnetic steel sheet used for a core material of a motor or a generator.
[0002]
[Prior art]
In recent years, demand for higher motor efficiency has been increasing due to increasing energy saving needs. In order to achieve high motor efficiency, it is essential to improve the performance of the electrical steel sheet used as the core material. For this reason, there is a strong demand for an electrical steel sheet having a high magnetic flux density and a low iron loss. In order to increase the magnetic flux density of the electrical steel sheet, it is effective to coarsen the crystal grain size before cold rolling, a technique for imparting a skin pass to the hot-rolled steel sheet and performing annealing (for example, Patent Document 1), A technique (for example, Patent Document 2) that performs high-temperature winding after hot rolling and performs self-annealing with the heat of the steel strip is disclosed. Furthermore, a technique (for example, Patent Document 3) is disclosed in which secondary recrystallization is generated before cold rolling to make crystal grains coarse and improve magnetic characteristics.
[0003]
[Patent Document 1]
Japanese Patent Publication No. 45-22211 [0004]
[Patent Document 2]
Japanese Patent Publication No.57-43132
[Patent Document 3]
Japanese Patent Laid-Open No. 3-21258
[Problems to be solved by the invention]
However, although all the techniques improve the magnetic properties in the rolling direction, there is a problem that the anisotropy of the magnetic properties increases and is not suitable for motor applications.
[0007]
This invention is made | formed in view of such a situation, and provides the manufacturing method of the non-oriented electrical steel sheet excellent in the magnetic characteristic with a high magnetic flux density and a low iron loss.
[0008]
[Means for Solving the Problems]
When the present inventors diligently studied to solve the above problems, Sn or Sb was added alone or in combination to add 0.01 to 0.05%, and the grain size before cold rolling was changed to 300 to 2000 μm. It has been found that the magnetic properties are reduced and excellent magnetic properties can be obtained.
[0009]
The present invention has been made based on such knowledge, and has the following configuration.
[0010]
In mass%, C: 0.005% or less, Si: 1.5% or less, Al: 0.1 to 1.0% or 0.004% or less, P: 0.2% or less, Mn: 0.05 -1.0%, S: 0.01% or less, N: 0.005% or less, Ti + V + Zr = 0.001-0.01%, Sn or Sb, each alone or in combination, 0.01-0.05% In addition, in order to sequentially perform hot rolling, hot-rolled sheet annealing, cold rolling, and finish annealing on steel consisting of the remaining Fe and inevitable impurities , the crystal grain size before cold rolling is 300 to 2000 μm, method for producing a non-oriented electrical steel sheet you.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described in detail based on experimental results.
[0012]
First, in order to investigate the influence of the grain size before cold rolling on the magnetic properties, C: 0.0025%, Si: 0.25%, Mn: 0.30%, P: 0.10%, S: 0.004%, tr. Steel with Al, N: 0.0021%, V: 0.002% was melted in a laboratory, and after hot rolling, pickling was performed. Subsequently, this hot-rolled sheet was subjected to hot-rolled sheet annealing at 850 ° C. for 2 minutes to 20 hours in a 75% H ₂ -25% N ₂ atmosphere, and then cold-rolled to a sheet thickness of 0.50 mm, and 10% H ₂ -90. Finish annealing was performed at 800 ° C. for 1 min in a% N ₂ atmosphere. FIG. 1 shows the relationship between the grain size before cold rolling and the anisotropy (B _L −B _C ) / B _L of the magnetic flux densities B50 and B50 of the sample thus obtained. Here, the measurement of magnetic properties was performed by the 25 cm Epstein method.
[0013]
From FIG. 1, when the grain size before cold rolling becomes 300 μm or more, the magnetic characteristics are greatly improved, and a further excellent magnetic flux density is obtained in a region exceeding 500 μm. Although excellent magnetic properties can be obtained even when the crystal grain size exceeds 2000 μm, the upper limit of the grain size before cold rolling is set to 2000 μm because it tends to cause plate breakage during cold rolling. From the above, the grain size before cold rolling is set to 300 to 2000 μm.
[0014]
However, it can be seen that when the crystal grains are 300 μm or more, an excellent magnetic flux density is obtained and the anisotropy is also increased. Therefore, the effect of various elements was investigated for the purpose of reducing anisotropy. As a result, the found element is Sn. Hereinafter, the effect of Sn will be described based on experimental results.
[0015]
In order to investigate the effect of Sn on anisotropy, C: 0.0026%, Si: 0.25%, Mn: 0.25%, P: 0.020%, tr. Al, S: 0.003%, N: 0.0020%, V: 0.003%, and the Sn amount is tr. The steel changed in a range of ˜600 ppm was melted in the laboratory, and pickled after hot rolling. Subsequently, this hot-rolled sheet was subjected to hot-rolled sheet annealing at 860 ° C. × 20 hr in an atmosphere of 75% H ₂ -25% N ₂ , and then cold-rolled to a sheet thickness of 0.50 mm, and 10% H ₂ -90% N Finish annealing was performed in ₂ atmospheres at 800 ° C. for 1 min. FIG. 2 shows the relationship between the Sn amount of the sample thus obtained and the anisotropy (B _L −B _C ) / B _L of B50. Here, the measurement of magnetic characteristics was performed by the 25 cm Epstein method.
[0016]
FIG. 2 shows that anisotropy decreases in the region where the Sn content is 100 ppm or more. Here, the reason why the anisotropy is decreased by the addition of Sn is not clear, but it is considered that Sn segregated at the grain boundary changed the recrystallization texture. However, when Sn is further added and Sn> 500 ppm, the grain growth property decreases and the iron loss increases. From the above, Sn is set to 100 to 500 ppm.
[0017]
The above effect of reducing anisotropy was also observed when Sb, which is a grain boundary segregation element similar to Sn, was added in an amount of 100 ppm or more. From the above, Sb is set to 100 ppm or more like Sn, and the upper limit is set to 500 ppm from the viewpoint of iron loss.
[0018]
Furthermore, even when Sb and Sn are added in combination, anisotropy decreases in the same manner as above when Sb + Sn is added at 100 ppm or more, and an increase in iron loss is observed when Sb + Sn is added above 500 ppm. It was. From this, when Sb and Sn are added in combination, Sb + Sn is set to 100 ppm or more, and from the viewpoint of iron loss, it is set to 500 ppm or less.
[0019]
Next, the reasons for limiting other components will be described.
[0020]
Si is an effective element for increasing the specific resistance of the steel sheet, but when it exceeds 1.5%, the magnetic flux density decreases, so the upper limit was made 1.5%.
[0021]
Al, like Si, is an effective element for increasing the specific resistance. However, if it exceeds 1.0%, the magnetic flux density decreases, so the upper limit was made 1.0%. Further, when it exceeds 0.004% to less than 0.1%, AlN becomes finer and grain growth property is lowered. Therefore, when Al is added, the lower limit is set to 0.1%. Further, when Al is not added, the content is made 0.004% or less.
[0022]
C has a problem of magnetic aging, so it is made 0.005% or less.
[0023]
Mn is required to be 0.05% or more in order to prevent red hot brittleness during hot rolling, but 0.05% to 1.0% in order to reduce the magnetic flux density when 1.0% or more.
[0024]
P is an element necessary for improving the punchability of the steel sheet, but if added over 0.2%, the steel sheet becomes brittle, so it was made 0.2% or less.
[0025]
V, Ti, and Zr are elements necessary for producing secondary recrystallization during hot-rolled sheet annealing and obtaining a coarse grain size before cold rolling. 0.001% or more. On the other hand, when V + Ti + Zr exceeds 0.01%, the grain growth property decreases and the iron loss increases, so the upper limit is made 0.01%.
[0026]
Next, the manufacturing method of the non-oriented electrical steel sheet excellent in the magnetic characteristics of this invention is demonstrated.
[0027]
The non-oriented electrical steel sheet of the present invention is manufactured such that the components and the grain size before cold rolling are within a predetermined range. That is, in order to obtain the steel plate of the present invention, for example, the molten steel blown in a converter is degassed and adjusted to a predetermined component, and then casting and hot rolling are performed. At this time, the finish annealing temperature and the coiling temperature at the time of hot rolling do not need to be particularly defined, and may be normal. Subsequently, after hot rolling, hot-rolled sheet annealing is performed. Here, the grain size before cold rolling can be adjusted by this hot-rolled sheet annealing. Next, after a predetermined sheet thickness is obtained by one cold rolling or two or more cold rollings with intermediate annealing, final annealing is performed.
[0028]
【Example】
Using the steel shown in Table 1, after defoaming in a converter, it is adjusted to the prescribed components, then cast, and the slab is heated at 1200 ° C. for 1 hr, and then the thickness is 2.0 mm. Hot rolling was performed. The hot rolling finishing temperature was 800 ° C. and the winding temperature was 700 ° C. Subsequently, the hot-rolled sheet annealing of the conditions shown in Table 1 was performed. Then, cold rolling was performed to a plate thickness of 0.5 mm, and finish annealing was performed at 850 ° C. × 1 min.
[0029]
The steel sheet obtained as described above was subjected to magnetic properties. Here, the magnetic measurement was performed using a 25 cm Epstein test piece. The magnetic properties of each steel sheet are also shown in Table 1.
[0030]
[Table 1]

[0031]
From Table 1, it can be seen that the steel of the present invention in which the steel plate components and the grain size before cold rolling are controlled within the range of the present invention has reduced anisotropy and excellent magnetic properties after finish annealing. In particular, excellent characteristics are obtained in a region where the crystal grain size exceeds 500 μm.
[0032]
On the other hand, the comparative steel is inferior in any one or more of iron loss, magnetic flux density, and anisotropy.
[0033]
【The invention's effect】
As described above, according to the present invention, a steel plate having a low iron loss and a high magnetic flux density can be obtained. By using the steel plate of the present invention, for example, high efficiency of a high efficiency induction motor can be achieved. Furthermore, the steel plate of the present invention is also effective in improving the efficiency of motors other than induction motors.
[Brief description of the drawings]
FIG. 1 is a diagram showing the relationship between grain size before cold rolling, magnetic flux density, and anisotropy.
FIG. 2 is a graph showing the relationship between Sn content and anisotropy.

Claims (1)

In mass%, C: 0.005% or less, Si: 1.5% or less, Al: 0.1 to 1.0% or 0.004% or less, P: 0.2% or less, Mn: 0.05 -1.0%, S: 0.01% or less, N: 0.005% or less, Ti + V + Zr = 0.001-0.01%, Sn or Sb, each alone or in combination, 0.01-0.05% In addition, in order to sequentially perform hot rolling, hot-rolled sheet annealing, cold rolling, and finish annealing on steel consisting of the remaining Fe and inevitable impurities , the crystal grain size before cold rolling is 300 to 2000 μm, method for producing a non-oriented electrical steel sheet you.

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