JP7428872B2 - Non-oriented electrical steel sheet and its manufacturing method - Google Patents

Description

The present invention relates to a non-oriented electrical steel sheet and a method for manufacturing the same.

Non-oriented electrical steel sheets are used, for example, in the iron core of motors. ) requires excellent magnetic properties, such as low iron loss and high magnetic flux density. Although various techniques have been proposed so far, it is difficult to obtain sufficient magnetic properties in all directions within the plate surface. For example, even if sufficient magnetic properties are obtained in a certain direction within the plate surface, sufficient magnetic properties may not be obtained in other directions.

Patent No. 4029430 Patent No. 6319465

SUMMARY OF THE INVENTION In view of the above-mentioned problems, an object of the present invention is to provide a non-oriented electrical steel sheet and a method for manufacturing the same that can obtain excellent magnetic properties on the average all around the circumference (average in all directions).

The present inventors conducted extensive studies to solve the above problems. As a result, in order to obtain an appropriate chemical composition and refine the cold-rolled structure without increasing the cold-rolling rate, the structure is refined by transformation from austenite to ferrite during hot rolling, and the structure is refined by stretching recrystallization (hereinafter referred to as It has become clear that it is important to facilitate the development of {100} crystal grains, which are normally difficult to develop, by generating bulging. It was also revealed that the {100} grains generated by bulging were further enriched by strain-induced grain boundary migration (SIBM) caused by the subsequent second cold rolling and annealing.

As a result of further intensive studies based on such knowledge, the present inventors have come up with the following aspects of the invention.

[1]
In mass%,
C: 0.0100% or less,
Si: 1.50% to 4.00%,
sol. Al: 0.0001% to 1.0%,
S: 0.0100% or less,
N: 0.0100% or less,
One or more types selected from the group consisting of Mn, Ni, Co, Pt, Pb, Cu, and Au: 2.50% to 5.00% in total,
Sn: 0.000% to 0.400%,
Sb: 0.000% to 0.400%,
P: 0.000% to 0.400%, and one or more selected from the group consisting of Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn, and Cd: 0.0000% to 0 in total Contains .0100%,
Mn content (mass%) is [Mn], Ni content (mass%) is [Ni], Co content (mass%) is [Co], Pt content (mass%) is [Pt], Pb content amount (mass %) is [Pb], Cu content (mass %) is [Cu], Au content (mass %) is [Au], Si content (mass %) is [Si], sol. The Al content (mass%) was determined by [sol. Al], the following formula (1) is satisfied,
The remainder has a chemical composition consisting of Fe and impurities,
Having a steel structure with an average grain size of 500 μm or less,
Non-directionality characterized by satisfying the following formula ( 2 ), where the value of B50 in the direction inclined at 45 degrees from the rolling direction is B50D1, and the value of B50 in the direction inclined at 135 degrees from the rolling direction is B50D2. Electromagnetic steel plate.
([Mn]+[Ni]+[Co]+[Pt]+[Pb]+[Cu]+[Au])-([Si]+[sol.Al])>0%...(1)
1.85T<(B50D1+B50D2)/2<1.94T...(2)

[2]
In mass%,
Sn: 0.020% to 0.400%,
Sb: 0.020% to 0.400%, and P: 0.020% to 0.400%
The non-oriented electrical steel sheet according to [1], characterized in that it contains one or more selected from the group consisting of:

[3]
In mass%,
One or more selected from the group consisting of Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn, and Cd: 0.0005% to 0.0100% in total [1 ] or the non-oriented electrical steel sheet according to [2].

[4]
A rotating electrical machine characterized by having an iron core made of the non-oriented electrical steel sheet according to any one of [1] to [3].

[5]
In mass%,
C: 0.0100% or less,
Si: 1.50% to 4.00%,
sol. Al: 0.0001% to 1.0%,
S: 0.0100% or less,
N: 0.0100% or less,
One or more types selected from the group consisting of Mn, Ni, Co, Pt, Pb, Cu, and Au: 2.50% to 5.00% in total,
Sn: 0.000% to 0.400%,
Sb: 0.000% to 0.400%,
P: 0.000% to 0.400%, and one or more selected from the group consisting of Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn, and Cd: 0.0000% to 0 in total Contains .0100%,
Mn content (mass%) is [Mn], Ni content (mass%) is [Ni], Co content (mass%) is [Co], Pt content (mass%) is [Pt], Pb content amount (mass %) is [Pb], Cu content (mass %) is [Cu], Au content (mass %) is [Au], Si content (mass %) is [Si], sol. The Al content (mass%) was determined by [sol. Al], the following formula ( 3 ) is satisfied,
A step of hot rolling a steel material having a chemical composition in which the balance consists of Fe and impurities;
performing a first cold rolling on the steel material after the hot rolling;
performing a first annealing on the steel material after the first cold rolling;
performing a second cold rolling on the steel material after the first annealing;
has
In the step of performing hot rolling, the final pass of finish rolling is performed at a temperature equal to or higher than the phase transformation point Ar1, the plate thickness after the final pass of finish rolling is tf, the plate thickness before the final pass is t1, and the final pass is When the plate thickness before the previous step is t2, the following equations ( 4 ) and ( 5 ) are satisfied,
The first cold rolling is performed at a reduction rate of 80% to 92%,
The method for producing a non-oriented electrical steel sheet according to any one of [1] to [3], characterized in that the second cold rolling is performed at a reduction rate of 5% to 25%.
([Mn]+[Ni]+[Co]+[Pt]+[Pb]+[Cu]+[Au])-([Si]+[sol.Al])>0%...( 3 )
0.4<tf/t1<0.8...( 4 )
0.4<t1/t2<0.8...( 5 )

[6]
The method for manufacturing a non-oriented electrical steel sheet according to [5], wherein the first annealing is performed at a temperature lower than Ac1.

[7]
Production of a non-oriented electrical steel sheet according to [5] or [6], further comprising a step of performing a second annealing for less than 1 hour at a temperature of less than Ac1 after the second cold rolling. Method.

[8]
The steel material is
In mass%,
Sn: 0.020% to 0.400%,
Sb: 0.020% to 0.400%, and P: 0.020% to 0.400%
The method for producing a non-oriented electrical steel sheet according to any one of [5] to [7], characterized in that the method contains one or more selected from the group consisting of:

[9]
The steel material is
In mass%,
One or more selected from the group consisting of Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn, and Cd: 0.0005% to 0.0100% in total [5 ] to [8]. The method for producing a non-oriented electrical steel sheet according to any one of [8].

[10]
When the rolling reduction ratio (%) of the first cold rolling is Rm and the rolling reduction ratio (%) of the second cold rolling is Rs, 86<Rm+0.2×Rs<92, and 5<Rs< The method for producing a non-oriented electrical steel sheet according to any one of [5] to [9], characterized in that the method satisfies 20.

According to the present invention, excellent magnetic properties averaged over the entire circumference can be obtained.

Embodiments of the present invention will be described in detail below.

First, the chemical composition of the steel material used in the non-oriented electrical steel sheet and the manufacturing method thereof according to the embodiment of the present invention will be explained. In the following description, "%", which is the unit of content of each element contained in a non-oriented electrical steel sheet or steel material, means "% by mass" unless otherwise specified. The non-oriented electrical steel sheet and steel material according to the present embodiment have a chemical composition in which ferrite-austenite transformation (hereinafter referred to as α-γ transformation) can occur, with C: 0.0100% or less and Si: 1.50% or more. 4.00%, sol. Al: 0.0001% to 1.0%, S: 0.0100% or less, N: 0.0100% or less, one or more types selected from the group consisting of Mn, Ni, Co, Pt, Pb, Cu, and Au. : 2.50% to 5.00% in total, Sn: 0.000% to 0.400%, Sb: 0.000% to 0.400%, P: 0.000% to 0.400%, and One or more selected from the group consisting of Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn, and Cd: Contains 0.0000% to 0.0100% in total, and the remainder is Fe and impurities. It has a chemical composition consisting of: Furthermore, Mn, Ni, Co, Pt, Pb, Cu, Au, Si and sol. The content of Al satisfies a predetermined condition described below. Examples of impurities include those contained in raw materials such as ore and scrap, and those contained in manufacturing processes.

(C: 0.0100% or less)
C increases iron loss and causes magnetic aging. Therefore, the lower the C content, the better. Such a phenomenon is remarkable when the C content exceeds 0.0100%. Therefore, the C content is set to 0.0100% or less. Reducing the C content also contributes to uniform improvement of magnetic properties in all directions within the plate surface. The lower limit of the C content is not particularly limited, but it is preferably 0.0005% or more, taking into account the cost of decarburization during refining.

(Si: 1.50% to 4.00%)
Si increases electrical resistance, reduces eddy current loss, reduces iron loss, increases yield ratio, and improves punching workability into an iron core. If the Si content is less than 1.50%, these effects cannot be sufficiently obtained. Therefore, the Si content is set to 1.50% or more. On the other hand, if the Si content exceeds 4.00%, the magnetic flux density decreases, the punching workability decreases due to an excessive increase in hardness, and cold rolling becomes difficult. Therefore, the Si content is set to 4.00% or less.

(sol.Al: 0.0001% to 1.0%)
sol. Al increases electrical resistance, reduces eddy current loss, and reduces iron loss. sol. Al also contributes to increasing the relative magnitude of the magnetic flux density B50 to the saturation magnetic flux density. Here, the magnetic flux density B50 is the magnetic flux density in a magnetic field of 5000 A/m. sol. If the Al content is less than 0.0001%, these effects cannot be sufficiently obtained. Furthermore, Al also has the effect of promoting desulfurization in steel manufacturing. Therefore, sol. Al content shall be 0.0001% or more. On the other hand, sol. If the Al content exceeds 1.0%, the magnetic flux density decreases, the yield ratio decreases, and the punching workability decreases. Therefore, sol. Al content shall be 1.0% or less.

(S: 0.0100% or less)
S is not an essential element and is contained, for example, as an impurity in steel. S inhibits recrystallization and crystal grain growth during annealing due to fine MnS precipitation. Therefore, the lower the S content, the better. The increase in core loss and decrease in magnetic flux density due to such inhibition of recrystallization and grain growth are significant when the S content exceeds 0.0100%. Therefore, the S content is set to 0.0100% or less. Note that the lower limit of the S content is not particularly limited, but it is preferably 0.0003% or more, taking into consideration the cost of desulfurization treatment during refining.

(N: 0.0100% or less)
Like C, N deteriorates magnetic properties, so the lower the N content, the better. Therefore, the N content is set to 0.0100% or less. Note that the lower limit of the N content is not particularly limited, but it is preferably 0.00100% or more in consideration of the cost of denitrification treatment during refining.

(One or more types selected from the group consisting of Mn, Ni, Co, Pt, Pb, Cu, and Au: 2.50% to 5.00% in total)
Since these elements are necessary for causing α-γ transformation, it is necessary to contain at least one of these elements in a total amount of 2.50% or more. On the other hand, if the total amount exceeds 5.00%, the cost may increase and the magnetic flux density may decrease. Therefore, the total content of at least one of these elements is 5.00% or less.

In addition, the following conditions are further assumed to be satisfied as conditions under which α-γ transformation can occur. In other words, Mn content (mass%) is [Mn], Ni content (mass%) is [Ni], Co content (mass%) is [Co], Pt content (mass%) is [Pt], Pb content (mass%) is [Pb], Cu content (mass%) is [Cu], Au content (mass%) is [Au], Si content (mass%) is [Si], sol. The Al content (mass%) was determined by [sol. Al], it is preferable that the following formula (1) is satisfied in terms of mass %.
([Mn]+[Ni]+[Co]+[Pt]+[Pb]+[Cu]+[Au])-([Si]+[sol.Al])>0%...(1)

If the above-mentioned formula (1) is not satisfied, the α-γ transformation does not occur and the magnetic flux density becomes low.

(Sn: 0.000% to 0.400%, Sb: 0.000% to 0.400%, P: 0.000% to 0.400%)
Sn and Sb improve the texture after cold rolling and recrystallization, and improve the magnetic flux density. Therefore, although these elements may be contained as necessary, if they are contained in excess, the steel becomes brittle. Therefore, the Sn content and the Sb content are both 0.400% or less. Further, P may be included in order to ensure the hardness of the steel sheet after recrystallization, but if it is included in excess, it will cause embrittlement of the steel. Therefore, the P content is set to 0.400% or less. In order to impart further effects such as magnetic properties as described above, 0.020% to 0.400% Sn, 0.020% to 0.400% Sb, and 0.020% to 0.400% % of P is preferably contained.

(One or more selected from the group consisting of Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn, and Cd: 0.0000% to 0.0100% in total)
Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn, and Cd react with S in the molten steel during casting of the molten steel to generate precipitates of sulfides, oxysulfides, or both of these. Hereinafter, Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn, and Cd may be collectively referred to as "coarse precipitate-forming elements." The particle size of the precipitates of coarse precipitate-forming elements is about 1 μm to 2 μm, which is much larger than the particle size (about 100 nm) of fine precipitates such as MnS, TiN, AlN, etc. Therefore, these fine precipitates adhere to the precipitates of the coarse precipitate-forming elements, making it difficult to inhibit recrystallization and crystal grain growth during intermediate annealing. In order to fully obtain these effects, it is preferable that the total content of these elements is 0.0005% or more. However, when the total amount of these elements exceeds 0.0100%, the total amount of sulfides, oxysulfides, or both becomes excessive, and recrystallization and crystal grain growth during intermediate annealing are inhibited. Therefore, the total content of coarse precipitate-forming elements is set to 0.0100% or less.

Next, the texture of the non-oriented electrical steel sheet according to this embodiment will be explained. The details of the manufacturing method will be described later, but the non-oriented electrical steel sheet according to this embodiment has a chemical composition in which α-γ transformation can occur, and the structure is refined by rapid cooling immediately after finish rolling in hot rolling. This results in a structure in which {100} crystal grains have grown. As a result, the non-oriented electrical steel sheet according to the present embodiment has, for example, an integrated strength of over 100 in the {100}<011> direction, and a particularly high magnetic flux density B50 in the 45° direction with respect to the rolling direction. In this way, although the magnetic flux density becomes high in a specific direction, a high magnetic flux density is obtained overall in all directions on average. When the integrated strength of the {100}<011> direction becomes 100 or less, the integrated strength of the {111}<112> direction, which lowers the magnetic flux density, becomes high, and the magnetic flux density decreases as a whole.

The integrated intensity in the {100}<011> direction can be measured by an X-ray diffraction method or an electron backscatter diffraction (EBSD) method. Since the reflection angle of X-rays and electron beams from the sample differs depending on the crystal orientation, the crystal orientation strength can be determined from the reflection intensity and the like using a randomly oriented sample as a reference.

Next, the thickness of the non-oriented electrical steel sheet according to this embodiment will be explained. The thickness of the non-oriented electrical steel sheet according to this embodiment is 0.50 mm or less. If the thickness exceeds 0.50 mm, excellent high frequency iron loss cannot be obtained. Therefore, the thickness should be 0.50 mm or less.

Next, the magnetic properties of the non-oriented electrical steel sheet according to this embodiment will be explained. When examining the magnetic properties, the value of B50, which is the magnetic flux density of the non-oriented electrical steel sheet according to this embodiment, is measured. In the produced non-oriented electrical steel sheet, one rolling direction cannot be distinguished from the other. Therefore, in this embodiment, the rolling direction refers to both directions. The value of B50 in the rolling direction is B50L, the value of B50 in the direction inclined at 45 degrees from the rolling direction is B50D1, the value of B50 in the direction inclined at 90 degrees from the rolling direction is B50C, the value of B50 in the direction inclined at 135 degrees from the rolling direction. When the value is B50D2, there is anisotropy in the magnetic flux density such that B50D1 and B50D2 are the highest and B50L+B50C is the lowest.

Here, for example, when considering the omnidirectional (0° to 360°) distribution of magnetic flux density with the clockwise (or counterclockwise) direction as the positive direction, the rolling direction is 0° (unidirectional) and 180°. degree (other direction), B50D1 has B50 values of 45° and 225°, and B50D2 has B50 values of 135° and 315°. The B50 value at 45° and the B50 value at 225° exactly match, and the B50 value at 135° and the B50 value at 315° match exactly. However, B50D1 and B50D2 may not match exactly because it may not be easy to make them have the same magnetic properties during actual manufacturing. The non-oriented electrical steel sheet according to this embodiment satisfies the following (2) using the average value of B50D1 and B50D2.
1.85T<(B50D1+B50D2)/2<1.94T...(2)

As described above, when the magnetic flux density is measured in this embodiment, a high magnetic flux density is confirmed in which the average value of B50D1 and B50D2 is 1.85 T or more and 1.94 T or less, as shown in equation (2).

Note that the above 45° is a theoretical value, and it may not be easy to match it to 45° in actual manufacturing, so it includes cases that do not strictly match 45°. This also applies to the angles of 135°, 225°, and 315°.

The magnetic flux density can be measured by cutting out a 55 mm square sample from a direction such as 45° with respect to the rolling direction, and using a single-plate magnetic measuring device.

Next, a method for manufacturing a non-oriented electrical steel sheet according to this embodiment will be explained. In this embodiment, hot rolling, cold rolling (first cold rolling), intermediate annealing (first annealing), skin pass rolling (second cold rolling), finish annealing (second annealing), Strain relief annealing (third annealing) etc. are performed.

First, the above-mentioned steel material is heated and hot rolled. The steel material is, for example, a slab manufactured by normal continuous casting. Rough rolling and finish rolling of hot rolling are performed at a temperature in the γ range (Ar1 or higher). That is, hot rolling is performed so that the finishing temperature of finish rolling becomes Ar1 or higher. As a result, the structure becomes finer by transforming from austenite to ferrite through subsequent cooling. If cold rolling is then performed in the refined state, overhang recrystallization (hereinafter referred to as bulging) is likely to occur, and {100} crystal grains, which are normally difficult to grow, can be made to grow easily.

In this embodiment, in the hot rolling process, when the plate thickness after the final pass of finish rolling is tf, the plate thickness before the final pass is t1, and the plate thickness one step before the final pass is t2, The following equations (3) and (4) are satisfied.
0.4<tf/t1<0.8...(3)
0.4<t1/t2<0.8...(4)

If either tf/t1 or t1/t2 is less than 0.4, a high strain will be applied in one pass, causing the steel plate to warp and making it difficult to control the steel plate during hot rolling. On the other hand, if either tf/t1 or t1/t2 is 0.8 or more, sufficient strain cannot be applied, and the grain size after hot rolling cannot be sufficiently reduced due to the phenomenon of dynamic recrystallization. Can not do it. Here, dynamic recrystallization refers to a phenomenon of recrystallization during rolling. Generally, in hot rolling, the reduction rate during finish rolling is low, so the amount of strain imparted is small, and recrystallization occurs after processing (static recrystallization). Dynamic recrystallization has many locations that serve as recrystallization nuclei, while static recrystallization is characterized in that there are fewer locations that serve as recrystallized grain nuclei. Therefore, dynamic recrystallization results in smaller crystal grain sizes than static recrystallization. Specifically, by utilizing dynamic recrystallization, an average grain size of 10 μm or less can be achieved in hot rolled sheets. As described above, when dynamic recrystallization is used, the crystal grain size after hot rolling can be made finer, so that bulging can be made more likely to occur.

Thereafter, the hot-rolled steel plate is wound up without being annealed, pickled, and then cold-rolled to the hot-rolled steel plate. In cold rolling, the reduction ratio is preferably 80% to 92%. When the rolling reduction is less than 80%, bulging is less likely to occur, and when the rolling reduction is over 92%, {100} grains tend to grow due to subsequent bulging. It becomes difficult to wind up the rolling material, and the operation becomes difficult.

After the cold rolling is completed, intermediate annealing is subsequently performed. In this embodiment, intermediate annealing is performed at a temperature that does not transform into austenite. That is, it is preferable that the temperature of intermediate annealing be less than Ac1. By performing intermediate annealing in this manner, bulging occurs and {100} crystal grains tend to grow. Further, the time for intermediate annealing is preferably 5 seconds to 60 seconds.

After the intermediate annealing is completed, skin pass rolling is performed next. As described above, when rolling and annealing are performed in a state where bulging has occurred (skin pass), {100} crystal grains further grow starting from the portion where bulging has occurred. This is due to skin pass rolling, where {100}<011> crystal grains are less likely to accumulate strain, while {111}<112> crystal grains are prone to strain, and subsequent annealing results in less strain. This is because the {111}<112> crystal grains are eaten away by the difference in strain used by the 011> crystal grains as a driving force. This grain erosion phenomenon, which occurs using the strain difference as a driving force, is called strain-induced grain boundary migration (hereinafter referred to as SIBM). The rolling reduction ratio of skin pass rolling is preferably 5% to 25%. If the rolling reduction is less than 5%, the amount of strain is too small, so strain-induced grain boundary migration (hereinafter referred to as SIBM) does not occur in subsequent annealing, and {100}<011> crystal grains do not become large. On the other hand, if the reduction rate exceeds 25%, the amount of strain becomes too large, and recrystallization nucleation (hereinafter referred to as nucleation) in which new crystal grains are generated from {111}<112> crystal grains occurs. In this nucleation, most of the grains produced are {111}<112> crystal grains, resulting in poor magnetic properties.

In addition, when making a non-oriented electrical steel sheet have a predetermined strain distribution, when the rolling reduction (%) during cold rolling is Rm and the rolling reduction (%) during skin pass rolling is Rs. , 86<Rm+0.2×Rs<92, and 5<Rs<20. It is preferable to adjust the rolling reduction ratio of cold rolling and skin pass rolling.

After skin pass rolling, finish annealing is performed to release strain and improve workability. Similarly, the final annealing temperature is set to a temperature that does not transform to austenite, and the final annealing temperature is lower than Ac1. By performing final annealing in this manner, the {100}<011> crystal grains attack the {111}<112> crystal grains, thereby improving the magnetic properties. Furthermore, the time required for the temperature to reach Ac1 from 600°C during final annealing is set to within 1200 seconds. If this annealing time is too short, most of the strain introduced by the skin pass will remain, causing warping when punching out a complex shape. On the other hand, if the annealing time is too long, the crystal grains will become too coarse, leading to large sagging during punching and resulting in poor punching accuracy.

When the final annealing is completed, the non-oriented electrical steel sheet is subjected to forming processing and the like in order to obtain the desired steel member. Then, the steel member made of a non-oriented electromagnetic steel sheet is subjected to strain relief annealing in order to remove distortion caused by forming or the like (for example, punching). In this embodiment, the temperature of strain relief annealing is set to about 800°C, and the time of strain relief annealing is set to about 2 hours, in order to generate SIBM and make the crystal grain size coarser below Ac1. do.

In the non-oriented electrical steel sheet (steel member) according to the present embodiment, among the above-mentioned manufacturing methods, the steel structure is mainly obtained by combining dynamic recrystallization by large reduction during hot rolling and skin pass rolling. The average crystal grain size at is a fine value of 500 μm or less, and a high magnetic flux density with B50 in the 45° direction of 1.85 T or more and 1.94 T or less (for example, 1.9 T) is obtained, and excellent magnetic properties are realized.

As described above, a steel member made of a non-oriented electrical steel sheet according to this embodiment can be manufactured.

A steel member made of a non-oriented electromagnetic steel sheet according to the present embodiment is applied, for example, to an iron core of a rotating electric machine. In this case, an iron core for use in a rotating electrical machine is produced by cutting out individual flat thin plates from the non-oriented electromagnetic steel sheet according to the present embodiment and laminating these flat thin plates as appropriate.
Since this iron core is made of non-oriented electrical steel sheet with excellent magnetic properties, iron loss is suppressed to a low level, and a rotating electric machine with excellent torque is realized.

Next, a non-oriented electrical steel sheet according to an embodiment of the present invention will be specifically described while showing examples. The examples shown below are merely examples of non-oriented electrical steel sheets according to embodiments of the present invention, and the non-oriented electrical steel sheets according to the present invention are not limited to the following examples.

(First example)
Ingots having the components shown in Table 1 below were produced by casting molten steel. Here, the left side of the equation represents the value on the left side of the above-mentioned equation (1). Thereafter, the produced ingot was heated to 1150° C. and hot rolled to a thickness of 2.5 mm. After completion of finish rolling, the hot rolled steel plate was cooled with water and wound up. The temperature at the stage of the final pass of finish rolling (finishing temperature) at this time was 830°C, which was all higher than Ar1. In addition, No. 1, in which γ-α transformation does not occur. Regarding No. 108, the finishing temperature was 850°C. At this time, the finishing plate thickness tf, the plate thickness t1 before finishing, and the plate thickness t2 before finishing two are shown in Table 1.

Next, scale was removed from the hot rolled steel plate by pickling, and cold rolling was performed. Table 1 shows the rolling reduction ratio at that time. Then, intermediate annealing was performed at 700° C. for 30 seconds in a non-oxidizing atmosphere. Next, a second cold rolling (skin pass rolling) was performed at the rolling reduction ratio shown in Table 1.

Next, after the second cold rolling (skin pass rolling), finish annealing was performed under the conditions shown in Table 1, and after creating a 55 mm square sample by shearing, strain relief annealing was performed under the conditions shown in Table 2. After that, the magnetic flux density B50 was measured. The measurement sample was a 55 mm square sample taken at an angle of 45° to the rolling direction. Then, the samples were measured, and the magnetic flux densities B50 at 45° and 135° with respect to the rolling direction were measured, respectively, and the average values are shown in Table 2.

The underlines in Table 1 indicate conditions outside the scope of the present invention. Invention example No. 101~No. 107, No. 109, No. 110, No. No. 113 had a good magnetic flux density B50 in the 45° direction. On the other hand, the comparative example No. In No. 108, the Si concentration was high, the value on the left side of the equation was 0 or less, and the composition did not undergo α-γ transformation, so the magnetic density B50 was low in all cases. Comparative example No. In No. 111, the magnetic flux density B50 was low because the rolling reduction was low in the final pass of hot rolling and in the previous pass. Comparative example No. No. 112 had a low magnetic flux density B50 because the relationship between cold rolling reduction and skin pass rolling reduction was outside the recommended conditions. Comparative example No. In No. 114, the strain relief annealing temperature was low and the SIBM was underdeveloped, so the magnetic flux density B50 was low.

(Second example)
Ingots having the components shown in Table 2 below were produced by casting molten steel. Thereafter, as shown in Table 3, the manufactured ingots were heated to 1150° C. and hot rolled to a plate thickness of 2.5 mm. After completion of finish rolling, the hot rolled steel plate was cooled with water and wound up. The finishing temperature at the stage of the final pass of finish rolling at this time was 830°C, which was all higher than Ar1. Further, the rolling reduction ratio of each pass at this time is as shown in Table 2.

Next, scale was removed from the hot rolled steel plate by pickling, and cold rolling was performed until the plate thickness became 0.30 mm. Then, intermediate annealing was performed in a non-oxidizing atmosphere, and the temperature of the intermediate annealing was controlled so that the recrystallization rate was 85%. Next, a second cold rolling (skin pass rolling) was performed until the plate thickness became 0.27 mm.

Next, in order to investigate the magnetic properties, after the second cold rolling (skin pass rolling), final annealing was performed at 800°C for 30 seconds, and a 55 mm square sample was prepared by shear processing, and then it was heated at 800°C for 2 hours. Strain relief annealing was performed and the magnetic flux density B50 was measured. The magnetic flux density B50 was measured using the same procedure as in the first example.

No. 201~No. No. 214 were all invention examples, and all had good magnetic properties. In particular, No. 202~No. 204 is No. 201, No. 205~No. The magnetic flux density B50 was higher than that of 214.

Claims (10)

In mass%,
C: 0.0100% or less,
Si: 1.50% to 4.00%,
sol. Al: 0.0001% to 1.0%,
S: 0.0100% or less,
N: 0.0100% or less,
One or more types selected from the group consisting of Mn, Ni, Co, Pt, Pb, Cu, and Au: 2.50% to 5.00% in total,
Sn: 0.000% to 0.400%,
Sb: 0.000% to 0.400%,
P: 0.000% to 0.400%, and
Contains a total of 0.0000% to 0.0100% of one or more selected from the group consisting of Mg , Ca, Sr, Ba, Ce, La, Nd, Pr, Zn, and Cd,
Mn content (mass%) is [Mn], Ni content (mass%) is [Ni], Co content (mass%) is [Co], Pt content (mass%) is [Pt], Pb content amount (mass %) is [Pb], Cu content (mass %) is [Cu], Au content (mass %) is [Au], Si content (mass %) is [Si], sol. The Al content (mass%) was determined by [sol. Al], the following formula (1) is satisfied,
The remainder has a chemical composition consisting of Fe and impurities,
Having a steel structure with an average grain size of 500 μm or less,
Non-directionality characterized by satisfying the following formula (2), where the value of B50 in the direction inclined at 45 degrees from the rolling direction is B50D1, and the value of B50 in the direction inclined at 135 degrees from the rolling direction is B50D2 Electromagnetic steel plate.
([Mn]+[Ni]+[Co]+[Pt]+[Pb]+[Cu]+[Au])-([Si]+[sol.Al])>0%...(1)
1.85T<(B50D1+B50D2)/2<1.94T...(2) In mass%,
Sn: 0.020% to 0.400%,
Sb: 0.020% to 0.400%, and P: 0.020% to 0.400%
The non-oriented electrical steel sheet according to claim 1, characterized in that it contains one or more selected from the group consisting of: In mass%,
A claim characterized in that it contains one or more selected from the group consisting of Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn, and Cd: 0.0005% to 0.0100% in total. The non-oriented electrical steel sheet according to 1 or 2. A rotating electrical machine comprising an iron core made of the non-oriented electrical steel sheet according to any one of claims 1 to 3. In mass%,
C: 0.0100% or less,
Si: 1.50% to 4.00%,
sol. Al: 0.0001% to 1.0%,
S: 0.0100% or less,
N: 0.0100% or less,
One or more types selected from the group consisting of Mn, Ni, Co, Pt, Pb, Cu, and Au: 2.50% to 5.00% in total,
Sn: 0.000% to 0.400%,
Sb: 0.000% to 0.400%,
P: 0.000% to 0.400%, and
Contains a total of 0.0000% to 0.0100% of one or more selected from the group consisting of Mg , Ca, Sr, Ba, Ce, La, Nd, Pr, Zn, and Cd,
Mn content (mass%) is [Mn], Ni content (mass%) is [Ni], Co content (mass%) is [Co], Pt content (mass%) is [Pt], Pb content amount (mass %) is [Pb], Cu content (mass %) is [Cu], Au content (mass %) is [Au], Si content (mass %) is [Si], sol. The Al content (mass%) was determined by [sol. Al], the following formula ( 3 ) is satisfied,
A step of hot rolling a steel material having a chemical composition in which the balance consists of Fe and impurities;
performing a first cold rolling on the steel material after the hot rolling;
performing a first annealing on the steel material after the first cold rolling;
performing a second cold rolling on the steel material after the first annealing;
has
In the step of performing hot rolling, the final pass of finish rolling is performed at a temperature equal to or higher than the phase transformation point Ar1, the plate thickness after the final pass of finish rolling is tf, the plate thickness before the final pass is t1, and the final pass is When the plate thickness before the previous step is t2, the following equations ( 4 ) and ( 5 ) are satisfied,
The first cold rolling is performed at a reduction rate of 80% to 92%,
4. The method for producing a non-oriented electrical steel sheet according to claim 1, wherein the second cold rolling is performed at a reduction rate of 5% to 25%.
([Mn]+[Ni]+[Co]+[Pt]+[Pb]+[Cu]+[Au])-([Si]+[sol.Al])>0%...( 3 )
0.4<tf/t1<0.8...( 4 )
0.4<t1/t2<0.8...( 5 ) 6. The method for manufacturing a non-oriented electrical steel sheet according to claim 5, wherein the first annealing is performed at a temperature lower than Ac1. The method for manufacturing a non-oriented electrical steel sheet according to claim 5 or 6, further comprising the step of performing a second annealing at a temperature lower than Ac1 for one hour or less after the second cold rolling. The steel material is
In mass%,
Sn: 0.020% to 0.400%,
Sb: 0.020% to 0.400%, and P: 0.020% to 0.400%
The method for producing a non-oriented electrical steel sheet according to any one of claims 5 to 7, characterized in that the method contains one or more selected from the group consisting of: The steel material is
In mass%,
A claim characterized in that it contains one or more selected from the group consisting of Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn, and Cd: 0.0005% to 0.0100% in total. The method for producing a non-oriented electrical steel sheet according to any one of items 5 to 8. When the rolling reduction ratio (%) of the first cold rolling is Rm and the rolling reduction ratio (%) of the second cold rolling is Rs, 86<Rm+0.2×Rs<92, and 5<Rs< The method for producing a non-oriented electrical steel sheet according to any one of claims 5 to 9, wherein the non-oriented electrical steel sheet satisfies 20.