JP3292846B2 - Non-oriented electrical steel sheet having good degree of orientation accumulation and grain growth and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-oriented electrical steel sheet used as a core material for electric equipment, and more particularly to a non-oriented electrical steel sheet having a good degree of orientation accumulation and grain growth, and a method for producing the same. .

[0002]

2. Description of the Related Art Efficiency of electric equipment is increasing worldwide.
In recent years, there is a strong demand for energy saving and global environmental conservation. In particular, in recent years, as non-oriented electrical steel sheets used as rotors or stators have become more efficient as rotating machines have become more efficient, materials that have better magnetic properties than the current situation, that is, materials with lower iron loss and higher magnetic flux density, have been developed. It is being sought. At the same time, the shape of the motor core becomes complicated, and good workability in punching is also strongly required as well as magnetic properties.

[0003] As a means of reducing the iron loss of a non-oriented electrical steel sheet, a method of increasing the content of alloying elements such as Si, Al and Mn to increase the electric resistance and reduce the eddy current loss is widely and generally used. I have. Further, after determining the components, attempts have been made to reduce the iron loss by adjusting the crystal grain size after forming into a core to about 100 μm. On the other hand, with respect to the magnetic flux density, Si, Al, since the saturation magnetic flux density Bs will by adding alloy elements such as Mn is lowered, the magnetic flux density B ₅₀ is lowered. Thus, after determining the amounts of alloying elements in order to obtain a predetermined iron loss amount that Bs is decreased and does not improve the degree of integration of preferred crystal orientation on the magnetic properties with the Bs drop B ₅₀ also decreases. Therefore, means for improving the degree of crystal orientation integration by adjusting alloy elements or changing process conditions has been required.

[0004] Regarding workability, it has recently been found that, when punching a motor core, if the crystal grain size of the steel sheet is too large, problems such as burrs and burrs occur. However, if the crystal grain size of the product sheet is too small, the core loss of the core deteriorates. For this reason, there has been an increasing need for non-oriented electrical steel sheets which have a small crystal grain size during core punching and allow crystal grains to grow to some extent during strain relief annealing of the core.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a non-oriented electrical steel sheet having a high degree of integration of crystal orientations preferable for magnetic properties and good crystal grain growth during strain relief annealing by a user.
And a method for producing the same.

[0006]

The gist of the present invention is as follows. (1) In mass%, C: 0.0005% or more and 0.010% or less, Mn: 0.1%
0.5% or less, Si: 0.6% or more and 1.4% or less, Al: 0.9% or more 1.6
% Or less, and a component that satisfies 1.6% ≦ Si + Al ≦ 2.7%, with the balance being a non-oriented electrical steel sheet comprising Fe and unavoidable impurity elements, the magnetic flux density B ₅₀ after strain relief annealing is changed to the saturation magnetic flux density Bs in divided by the B ₅₀ / Bs is, B ₅₀ / Bs ≧ 0.83,
A non-oriented electrical steel sheet having a good degree of orientation accumulation and grain growth, wherein the iron loss W _15/50 satisfies W _15/50 ≦ 3.01 W / kg . (2) In mass%, C: 0.0005% or more and 0.010% or less, Mn: 0.1%
0.5% or less, Si: 0.6% or more and 1.4% or less, Al: 0.9% or more 1.6
% Or less, and a component that satisfies 1.6% ≦ Si + Al ≦ 2.7%, and the rest is hot-rolled a slab made of Fe and unavoidable impurity elements, then hot-rolled sheet annealing and one cold-rolling, or In a method for producing a non-oriented electrical steel sheet in which cold rolling is performed twice or more with intermediate annealing followed by finish annealing, the temperature of hot-rolled sheet annealing or the last intermediate annealing is set to 950 ° C or more. A method for producing a non-oriented electrical steel sheet characterized by good orientation accumulation and grain growth characteristics. (3) Set the maximum value of the steel sheet temperature in the final cold rolling to 150
(2) The method for producing a non-oriented electrical steel sheet according to (2), wherein the non-oriented electrical steel sheet has a good degree of orientation accumulation and grain growth. (4) The steel according to any one of (1) to (3), wherein the amount of S contained in the steel does not exceed 0.004% by mass%.
Non-oriented electrical steel sheet with good orientation orientation and grain growth
And its manufacturing method.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Although the present inventors have low iron loss,
In order to develop a non-oriented electrical steel sheet that has a good degree of crystallographic orientation and allows crystal grains to grow during strain relief annealing, we have conducted intensive research on components and manufacturing conditions for improving the degree of orientational accumulation. The present invention will be described in detail based on the following experiments.

[0008] Vacuum melting was performed in a laboratory, and raw materials in which the amounts of Si and Al were changed as shown in Table 1 were prepared. At this time, the other components are Mn: 0.2%, C: 0.001 to 0.002%, S: 0.001 to 0.00
2%, N: 0.001 to 0.002%, Ti: 0.0015 to 0.0025%. A hot-rolled sheet having a thickness of 2.3 mm was prepared from this material and annealed at an annealing temperature of 1000 ° C. for 60 seconds. Subsequently, pickling was performed, and then cold-rolled to a sheet thickness of 0.50 mm.
Continuous annealing was performed at 30 ° C. for 30 seconds. The annealing temperature is lower than the normal annealing temperature, because the user does not have problems such as burrs and burrs when punching a core. At this time, when the crystal grain size of each sample was measured by the line segment method, it was all 40 to 50 μm.

Further, each sample was sheared to a size capable of measuring a single-plate magnetic property, and then subjected to box annealing in a hydrogen atmosphere at a temperature of 750 ° C. for 2 hours. This annealing corresponds to annealing performed for the purpose of removing distortion after punching a core by a user. Table 1 shows the magnetic flux density B ₅₀ (5000 A / m) after box annealing.
Magnetic flux density), the iron loss W _15/50 (maximum magnetic flux density at a magnetic field of
The results of measurement of 1.5T iron loss at a frequency of 50 Hz) and the crystal grain size are shown. The saturation magnetic flux density Bs for each component is also shown. This Bs is a value calculated by a regression equation in the following equation (1).

Bs (T) = 2.1473−0.0382 × Si (%) − 0.0658 × Al (%) (1) From Table 1, the iron loss is 3.0 W / kg or less and the crystal grain size is 70 μm.
m or more, and when the degree of integration of crystal orientations with good magnetic properties is simply represented by B ₅₀ / Bs, the component range where the value is 0.83 or more is 0.6 ≦ Si ≦ 1.4%, 0.9 ≦ Al ≦ It was found that the range satisfies 1.6% and 1.6 ≦ Si + Al ≦ 2.7%.

[0011]

[Table 1]

The results in Table 1 will be described in more detail with reference to FIG. The material indicated by x in FIG. 1 has a core loss W _15/50 of 3 W
/ kg, and 1, 2, 3,
4, 6, 7, 11, and 16. These materials are
It is presumed that the eddy current loss increased due to low Si and Al contents and low specific resistance, resulting in the iron loss value exceeding 3 W / kg.

In FIG. 1, the material indicated by △ has an iron loss of 3 W / k.
g, but the azimuth integration degree B ₅₀ / Bs is less than 0.83, and the symbols in Table 1 indicate 21, 26, 27, 31, 3
It corresponds to 2. The fact that this material has a poor degree of azimuthal integration was first clarified this time, and indicates that a certain amount of Al is required in the additive element component. The material indicated by □ in FIG. 1 has an iron loss of 3 W / kg or less and a degree of orientation integration of B ₅₀ / Bs 0.83 or more, but has a crystal grain size of 70 μm.
Less, that is, the grain growth in box annealing was inferior, and the symbols in Table 1 indicate that 5,10,15,20,2
5, 29, 30, 33, 34, 35. It is presumed that these materials had excessive amounts of Si and Al, so that the crystal grain growth was inferior.

In FIG. 1, the material indicated by ● is iron loss 3W / kg.
Or less, and the orientation integration degree B ₅₀ / Bs is 0.83 or more, and the crystal grain size is 70 μm or more.
2,13,14,17,18,19,22,23,2
4, 27 and 28. (These are both an invention steel.) These samples are all 0.6% ≦ Si ≦ 1.4%, 0.
9% ≤ Al ≤ 1.6% , 1.6% ≤ Si + Al ≤ 2.7% at the same time, iron loss due to the addition of appropriate amounts of Si and Al
The orientation integration degree B ₅₀ / Bs is as high as 0.83 or more because the amount of Al in the additive element is as low as 3 W / kg or less, and the crystal grain growth is also good because there is not too much Si and Al. Inferred.

Next, in order to confirm the effect of hot-rolled sheet annealing,
The following experiment was performed. Of the materials used in the experiments in Table 1,
2.3mm thick hot rolled sheets were prepared from five types of 8, 17, 18, 19 and 28, and the annealing temperatures were 900 ° C, 950 ° C, 1000 ° C,
Annealing was performed for 60 seconds under four conditions of 1050 ° C. Subsequent processes were performed in the same manner as the experiment in Table 1. Table 2 shows the measurement results of the magnetic flux density _B50 , the iron loss _{W15 / 50} , and the crystal grain size after box annealing. The saturation magnetic flux density Bs for each component is also shown.

As shown in Table 2, the hot-rolled sheet annealing temperature was set to 950 ° C. or higher regardless of the composition of the material and despite the fact that there was almost no difference in the crystal grain size after box annealing. It was found that good magnetic properties could be obtained in the above.

[0017]

[Table 2]

Next, the reasons for limiting the numerical values of the conditions in the present invention will be described. The lower limit of C is set to 0.0005% and the upper limit is set to 0.010%. As shown in Example 1, the effect of improving the texture due to the presence of solid solution C is lost at 0.0005% or less, and the iron loss is caused by the presence of carbide at 0.010% or more. Is deteriorated. Mn
The lower limit of 0.1% and the upper limit of 0.5% is that Mn is 0.1% or less.
This is because S precipitates finely and has a large adverse effect on the grain growth, and when it is 0.5% or more, solute Mn deteriorates the grain growth. A better range is 0.2 to
0.3%.

The range of Si and Al is 0.6% ≦ Si ≦ 1.4%, 0.9% ≦
Al ≦ 1.6% and 1.6% ≦ Si + Al ≦ 2.7%. The reason for this is that, as already described in detail in FIG. 1, in a region where the amounts of Si and Al are too small, the iron loss W15 / 50 is inferior because the specific resistance is small, and the amount of Al is small although the amount of Si + Al is sufficient. In the region, the orientation integration degree B ₅₀ / Bs is inferior, and when the amount of Si and Al is too large, the grain growth becomes inferior. That is, 0.6% ≦ Si ≦ 1.4%, 0.9% ≦ Al ≦ 1.6% , and
Within the range of 1.6% ≦ Si + Al ≦ 2.7%, all of the iron loss, the degree of orientation accumulation, and the grain growth are good. Of these, a more favorable range is 0.7% ≦ Si ≦ 1.1%, and 1.0% ≦ Al ≦ 1.3%, and iron loss W _15/50 ≦ 2.9 W / kg, B ₅₀ / Bs
≧ 0.84 and crystal grain size ≧ 90 μm.

The lower limit of the azimuth integration degree B ₅₀ / Bs is set to 0.83 because if the value is low, the characteristics of the material components cannot be fully utilized. In addition,
The B ₅₀ value in this case is a value after strain relief annealing at a temperature of 750 ° C. for 2 hours.
The average value in the direction. Since the iron loss and the grain growth are dependent on the conditions of the strain relief annealing by the user, they are not particularly specified, but it is clear that both the iron loss and the grain growth are good within the above ranges of Si and Al. It is more obvious than one.

Further, from the viewpoint of grain growth, it is preferable that the amount of S, N, Ti, Zr, etc. present in the steel as an impurity is small.
In particular, as for S, which greatly affects the grain growth, as shown in Example 2, the content is preferably 0.004% or less. Next, the operating conditions of each step will be described. After hot rolling the slab heated slab, it is necessary to perform hot rolled sheet annealing at 950 ° C or higher. The reason for this is as shown in Example 3 in order to increase the crystal grain size before cold rolling to some extent, to increase the Goss orientation preferred for magnetic properties after finish annealing, and to improve the orientation integration degree B ₅₀ / Bs.

Next, cold rolling is performed to obtain a predetermined thickness. At this time, the cold rolling reduction is preferably performed at about 70 to 90%. This is outside the range of this rolling rate
This is because a crystal orientation unfavorable for magnetic properties is generated by finish annealing, and deteriorates the degree of orientation integration B ₅₀ / Bs. Further, the maximum value of the steel sheet temperature during cold rolling is preferably 150 ° C. or more as shown in the fourth embodiment. The maximum value of the steel sheet temperature in this case means the maximum value of the steel sheet temperature at each stand when the steel sheet is passed through a tandem-type cold rolling mill, and is usually the temperature at the final stand. The temperature of this steel plate is 150
C or higher is preferable because the presence of solid solution C
At 150 ° C or higher, dislocation sticks, changes the deformation mode during rolling, and as a result, after finishing annealing, favorable Goss
Due to the generation of crystal grains of the orientation, the orientation accumulation degree B ₅₀ / Bs
Is improved.

The cold-rolled steel sheet is finish-annealed.
The annealing method may be a known method, and is performed in a non-oxidizing atmosphere composed of nitrogen and hydrogen in a temperature range of 750 to 1100 ° C. for 5 seconds to
Usually, continuous annealing for 10 minutes is performed. At this time, if the annealing temperature is 900 ° C. or less, the recrystallized grain size is about 50 μm.
Therefore, problems such as burrs and burrs at the time of core punching by the user can be reduced, and recrystallization can easily proceed in strain relief annealing after core formation.

Next, the steel sheet subjected to the finish annealing is coated with an insulating film to obtain a product. After the steel sheet is punched into the desired shape and size by the user and laminated to form a core,
The strain relief annealing is performed at a temperature of 700 ° C. or more in a non-oxidizing atmosphere such as nitrogen.

[0025]

[0026]

[0027]

( Example 1 ) Si 1.3%, Al 1.3 and 1.7%, Mn: 0.2%, C: 0.0010-0.
0015%, the amount of S was variously changed, and vacuum melting was performed in a laboratory. A hot-rolled sheet having a thickness of 2.2 mm was prepared from this material, annealed at a temperature of 1000 ° C. for 50 seconds, and then pickled.
Subsequently, after the sheet thickness was reduced to 0.50 mm by cold rolling, finish annealing was performed at a temperature of 870 ° C. for 30 seconds. Further, the sample was sheared for SST measurement and subjected to strain relief annealing at a temperature of 750 ° C. for 2 hours. Table 3 shows the magnetic measurement results and the crystal grain size measurement results after the strain relief annealing.

Samples 5 to 8 have a crystal grain size of less than 70 μm, which is not preferable from the viewpoint of grain growth. Samples 1-4
Is W _15/50 ≦ 3.0W / kg, crystal grain size ≧ 70μm, degree of orientation integration B
₅₀ / Bs ≧ 0.84, and all of the iron loss, the grain growth, and the degree of orientation accumulation are in the preferable ranges. Among the samples 1 to 4, samples 1 to 3 in which S ≦ 40 ppm are more preferable from the viewpoint of iron loss and grain growth, and sample 1 in which S ≦ 20 ppm is further preferable from the viewpoint of grain growth. , 2.

[0030]

[Table 3]

Example 2 Vacuum melting was performed in a laboratory, and Si 1.4%, Al 0.5,
8%, Mn: 0.2%, C: 0.0012%, S: 0.0031% steel ingots were produced. This material was heated and hot-rolled to produce a hot-rolled sheet having a thickness of 2.2 mm, annealed at various temperatures for 60 seconds, and pickled. Subsequently, after cold rolling to a sheet thickness of 0.50 mm,
At 30 ° C. for 30 seconds. Further, the sample was sheared for SST measurement and subjected to strain relief annealing at a temperature of 750 ° C. for 2 hours. Table 4 shows the magnetic measurement results and the crystal grain size measurement results after the strain relief annealing.

Samples 1 to 5 have an azimuth integration degree B ₅₀ / Bs of 0.83
Less than that is not preferable. This is because the amount of Al is small. On the other hand, also in the sample 6, the azimuth integration degree B ₅₀ / Bs is 0.83
Less than that is not preferable. The reason for this is that since the hot-rolled sheet annealing temperature is low, the crystal grain size before cold rolling is small, and as a result, the Goss orientation preferred for magnetic properties in the product sheet is small.
Samples 7 to 10 are all preferred in terms of iron loss, grain growth, and degree of orientation accumulation. Among them, more preferred ranges are samples 8 to 10 in which the hot-rolled sheet annealing temperature is 1000 ° C or higher.

[0033]

[Table 4]

(Example 3) Vacuum melting was performed in a laboratory, and Si 0.9%, Al 1.6 and 1.
9%, Mn: 0.3%, C: 0.0026%, S: 0.0028% steel ingots were produced. This material was heated and hot rolled to produce a hot-rolled sheet having a thickness of 2.3 mm, annealed at various temperatures for 60 seconds, and pickled. Subsequently, in cold rolling, the plate thickness was 1.69 mm, 1.25 mm, 0.
The steel sheet was heated at various temperatures to 92 mm and 0.68 mm, respectively, and cold-rolled to a final thickness of 0.50 mm. This method simulates the temperature at each stand during actual rolling. Further, these steel sheets were subjected to finish annealing at a temperature of 850 ° C. for 30 seconds. Further, the sample was sheared for SST measurement and subjected to strain relief annealing at a temperature of 750 ° C. for 2 hours. Table 5 shows the magnetic measurement results and the crystal grain size measurement results after the strain relief annealing.

Samples 6 to 10 have a crystal grain size of less than 70 μm, which is not preferable from the viewpoint of grain growth. Samples 1 to 5 are W
_15/50 ≦ 3.0W / kg, crystal grain size ≧ 70μm, degree of orientation integration B ₅₀ /
Bs ≧ 0.83, and iron loss, grain growth, and degree of orientation accumulation are all in the preferred ranges. Further, a more preferable range of Samples 6 to 10 is Samples 8 to 10 in which B ₅₀ /Bs≧0.86.
It is. The reason for this is that by performing the cold rolling at 150 ° C. or higher, the crystal grains of the Goss orientation favorable for the magnetic properties in the product sheet increased.

[0036]

[Table 5]

[0037]

According to the present invention, it is possible to provide a non-oriented electrical steel sheet which has a high degree of integration of crystal orientations favorable for magnetic properties and has good crystal grain growth during strain relief annealing by a user, and a method for producing the same. Becomes

[Brief description of the drawings]

FIG. 1 shows the relationship between steel sheet components and characteristics evaluation results.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Ryutaro Kawamata 20-1 Shintomi, Futtsu-shi, Chiba Nippon Steel Corporation Technology Development Division (72) Inventor Kazufumi Hanzawa 1--1 Tobata-cho, Tobata-ku, Kitakyushu, Fukuoka 1 Inside Nippon Steel Corporation Yawata Works (72) Inventor Yoshihiro Arita 1-1 Inhachicho, Tobata-ku, Kitakyushu-shi, Fukuoka Prefecture Inside Nippon Steel Corporation Yawata Works (72) Inventor Hiroaki Sato Himeji, Hyogo Prefecture 1 Fujimachi, Hirohata-ku, Nippon Steel Corporation Hirohata Works (56) References JP-A-3-2323 (JP, A) JP-A-2000-129409 (JP, A) JP-A-10-183311 ( JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) C22C 38/00 303 C21D 8/12 C22C 38/06

Claims (4)

(57) [Claims] (1) In mass%, C: 0.0005% or more and 0.010% or less,
Mn: 0.1% or more and 0.5% or less, Si: 0.6% or more and 1.4% or less, Al: 0.9
% To 1.6% or less, and contain components that satisfies 1.6% ≦ Si + Al ≦ 2.7 %, the balance in the non-oriented electrical steel sheet consisting of Fe and unavoidable impurity elements, the saturation magnetic flux density B ₅₀ after stress relief annealing The value B ₅₀ / Bs divided by the magnetic flux density Bs is B ₅₀ / Bs ≧
A non-oriented electrical steel sheet having a good degree of orientation accumulation and grain growth, characterized by 0.83 and an iron loss W _15/50 satisfying W _15/50 ≦ 3.01 W / kg . 2. In mass%, C: 0.0005% or more and 0.010% or less,
Mn: 0.1% or more and 0.5% or less, Si: 0.6% or more and 1.4% or less, Al: 0.9
% Or more and 1.6% or less, and a component satisfying 1.6% ≦ Si + Al ≦ 2.7%, the remainder being a hot-rolled steel slab consisting of Fe and unavoidable impurity elements, followed by hot-rolled sheet annealing and one cold In a method for producing a non-oriented electrical steel sheet in which rolling or cold rolling is performed two or more times with intermediate annealing followed by finish annealing, the temperature of hot-rolled sheet annealing or the last intermediate annealing is set to 950 ° C.
A method for producing a non-oriented electrical steel sheet having a good degree of orientation accumulation and grain growth, as described above. 3. The method for producing a non-oriented electrical steel sheet according to claim 2, wherein the maximum value of the steel sheet temperature in the final cold rolling is 150 ° C. or more. . 4. The amount of S contained in steel is 0.004% by mass%.
Any one of claims 1 to 3, which does not exceed
Non-directional electrode with good orientation accumulation and grain growth
Magnetic steel sheet and its manufacturing method.