WO2003002777A1 - Nonoriented electromagnetic steel sheet - Google Patents

Abstract

A nonoriented electromagnetic steel sheet, wherein it has the following chemical composition, in mass %: C: 0 to 0.010 %, Si and/or Al: 0.03 to 0.5 or more than 0.5 % and not more than 2.5 %, Mn: 0.5% or less, P: 0.10 % to 0.26 %, S: 0.015 % or less, N: 0.010 % or less and balance: Fe and inevitable impurities. The nonoriented electromagnetic steel sheet exhibits excellent dimensional precision in blanking, and further, exhibits excellent magnetic balance of high magnetic flux density-low iron loss in a low Si steel, and excellent high magnetic flux density-high strength balance in a middle to high Si steel.

Description

 TECHNICAL FIELD The present invention relates to a non-oriented electrical steel sheet used as an iron core material in the Electric Sea. In particular, non-oriented electrical steel sheets suitable for iron core materials such as reluctance motors or embedded magnet type DC brushless motors that require higher strength, which require high punching dimensional accuracy and high magnetic flux density, are also required. It concerns the manufacturing method. BACKGROUND ART Non-oriented electrical steel sheets are soft magnetic materials that are mainly used as iron core materials for electric motors and transformers. In order to improve the efficiency and reduce the size of these electrical devices, it is required that the magnetic steel sheets have low iron loss and high magnetic flux density. In the field of electric motors, the magnetic properties of magnetic steel sheets, which are core materials, are being improved, that is, lower iron loss and higher magnetic flux density are being pursued.The motors themselves are also more efficient than conventional asynchronous AC induction motors. The use of synchronous motors and the improvement of characteristics are rapidly progressing.

Synchronous motors are generally surface magnet type (S PM) and embedded magnet type (I PM) DC brushless motors, and reluctance motors that use reluctance strikes generated by the magnetic saliency of the rotor and stator. are categorized. Above all, in the case of a reluctance motor, the amount of generated torque depends on the shapes of the rotor and the stator, the gap between the stator and the stator, and the magnetic flux density of the material. Therefore, as a core material for a reluctance motor, high magnetic flux density and high dimensional accuracy in punching are more important than other motors. In addition, with the progress of inverters, the number of poles tends to increase with higher speeds in order to improve motor efficiency and torque. Since these are all elements that increase the operating frequency, not only the conventional magnetic characteristics at the commercial frequency (50 to 60 Hz), but also 400 Hz It is also necessary to improve the magnetic characteristics in the high frequency range.

 Until now, various efforts have been made to improve the magnetic flux density and iron loss of the non-oriented electrical steel sheet as described above.

 In order to reduce the iron loss of non-oriented electrical steel sheets, it is common to increase the Si content.For example, about 3.5 mass% of Si is added to the highest grade non-oriented electrical steel sheets. There are ^^ However, as the Si content increases, the iron loss decreases, but the magnetic flux density also decreases.

 —On the other hand, low-grade non-oriented electrical steel sheets have a relatively high magnetic flux density due to the reduced Si content, but have the problem of high iron loss. As a method for improving iron loss of such low Si steel, Japanese Patent Application Laid-Open No. Sho 62-267421 discloses a non-directional steel sheet having an Si content of 0.6 mass% or less and an A1 content of 0.15 to 0.60 mass%. In electrical steel sheets, the amount of impurities such as C, S, N, and O is regulated to reduce inclusions and harmlessness that hinder crystal grain growth, promote grain growth, and reduce iron loss. Techniques to achieve this have been proposed. However, since the grain growth of such a low Si steel involves a reduction in strength, there is a problem that the punching surface becomes droopy and has a large force during punching, resulting in a marked decrease in punching performance.

Incidentally, as a method of improving the punching property by adjusting the hardness of the low Si steel, there is a technique of adding P of about 0.08 to 0.1 mass%, and for example, Japanese Patent Application Laid-Open No. 56-130425 discloses A technique for improving the punchability by adding less than 0.2 raass% of P is disclosed. Japanese Patent Application Laid-Open No. 2-66138 discloses a technique for positively adding P to low-Si steel, in which the amount of Si is suppressed to 0.1 mass% or less and A1 is set to 0.1 to 1.0 mass%. % To the A1-added steel in the range of 0: 25% by mass, and the magnetic effect is improved by the combined effect of A1 and P. A method to improve is disclosed.

 However, in these technologies, the improvement in punchability by adding P only focused on suppressing the drooping of the steel sheet by adjusting its hardness, and no consideration was given to the dimensional accuracy after punching. Was.

On the other hand, in the case of embedded magnet type DC brushless motors as well, punching accuracy and high magnetic flux density are required from the viewpoints of high torque and compact size. In order to prevent the detached magnet, the strength of the electrical steel sheet must be kept high. As mentioned above, high-grade Si steel is advantageous from the viewpoint of strength, but low Si is desirable from the viewpoint of magnetic flux density, and it has been difficult to achieve both strength and magnetic flux density. Disclosure of the invention

(As described above, high magnetic flux density and low iron loss characteristics of non-oriented electrical steel sheets are common properties desired for all applications of non-oriented electrical steel sheets such as various motors and transformers. In particular, as a non-oriented electrical steel sheet material for reluctance motors, particularly high magnetic flux density and high dimensional accuracy are important in terms of operation principle.

 However, to date, no non-oriented electrical steel sheet has been found that has excellent magnetic properties such as high magnetic flux density and low iron loss, and yet has excellent punching properties, especially dimensional accuracy in punching. . In addition to these characteristics, no non-oriented electrical steel sheet has been found that further satisfies the strength requirements required for embedded magnet type DC brushless motors.

Furthermore, in addition to these magnetic properties and punching properties, non-oriented electrical steel sheets that have been considered to be able to respond to the recent high-speed rotation of motors and the high frequencies associated with multi-polarization have been developed. Had not been found. The present invention has been developed in view of the above-mentioned current situation, and is provided with iron core materials such as motors and transformers,

 • It has an unprecedented high magnetic flux density and low iron loss magnetic balance that is ideal as a core material that requires particularly high magnetic flux density and high dimensional accuracy like a reluctance motor. Excellent non-oriented electrical steel sheet, and,

 • Electromagnetic steel sheet that combines high magnetic flux density, high-strength characteristics that are important from the viewpoint of high-speed rotation of the rotor and prevention of scattering of embedded magnets, along with dimensional accuracy

With its advantageous manufacturing method.

 For convenience, hereafter, the sum of Si and A1 is about 0.03raass% or more and 0.5raass% or less for low Si steel, and those for which the sum of Si and A1 exceeds 0.5mass% are medium to high. It is called Si steel.

(Means for Solving the Problems) The inventors of the present invention have conducted intensive studies to achieve the above object, and as a result, the amount of Si and A1 has been reduced to a low Si steel level, and the saturation magnetic flux density has been essentially reduced. By adjusting the average crystal grain size to a predetermined range and adding an appropriate amount of P, it is possible to obtain excellent magnetic properties such as high magnetic flux density, low force, and low iron loss. It was found that the punching dimensional accuracy was significantly improved. In addition to controlling the total amount of Si and A1 in the range of more than 0.05 raass% to about 2.5 raass ° / o, the addition of an appropriate amount of P has the effect of improving the punching dimensional accuracy. We have also learned that the strength can be greatly improved while maintaining the magnetic flux density, and that an unprecedented magnetic strength balance can be achieved.

The present invention is based on the above findings. That is, the gist configuration of the present invention is as follows. 1. in mass percentage

 C: O to 0.010%,

 Si and Z or Al: 0.03% or more, 0.5% or less in total,

 Mn: 0.5. /. Less than,

 P: 0.10% or more, 0.26% or less,

 S: 0.015% or less and

 N: 0.010% or less

And the remainder is composed of Fe and unavoidable impurities, and

 Average grain size: 以上 μπι or more, 80 m or less

Non-oriented electrical steel sheet with excellent magnetic properties and punching accuracy.

2. In (1) above, the steel sheet further increases by mass percentage.

 Sb and / "or Sn: 0.40% or less in total

Non-directional electromagnetic with excellent magnetic properties and punching accuracy characterized by containing

3. In 1 or 2 above, the steel sheet further increases by mass percentage.

 Ni: 2.3% or less

A non-oriented electrical steel sheet excellent in magnetic properties and punching accuracy, characterized by containing:

4. A non-oriented electrical steel sheet according to 1, 2, or 3 above, characterized in that the steel sheet has a thickness of 0.35 or less or less, and is excellent in magnetic properties and punching accuracy.

5. In mass percentage

 C: O to 0.010%,

Si and / or A1:> 0.5-2.5% in total, Mn: 0.5% or less,

 P: 0.10% or more, 0.26% or less,

 S: 0.015% or less and

 N: 0.010% or less, and

 Ni as required: 2.3% or less

Containing, power,

An index P _A represented by the following formula:

PA = -0.2XSi + 0.12XMn- 0.32XA1 + 0.05XNi ² +0.10 Ni + 0.36

 (1)

(However, the unit of the content of each element is mass%. The same applies to equation (2).)

P≤P _A

Or

An index P _F represented by the following formula:

Pp = -0.34XSi + 0.20XMn-0.54XA1 + 0.24XNi ² + 0.28XNi + 0.76

 (2)

 Pp≤0.26

 Is either satisfied,

 The balance consists of Fe and inevitable impurities, and is a magnetic steel sheet with excellent magnetic properties and excellent punching accuracy.

6. In 5 above, the steel sheet further increases by mass percentage.

 Sb and Z or Sn: 0.40% or less in total

A non-oriented electrical steel sheet with excellent strength, magnetic properties, and excellent punching accuracy. In the above-mentioned steel types, as the secondary contained elements, Ca: 0.01% or less, B: 0.005% or less, Cr: 0.1% or less, Cu: 0.1% or less, Mo: 0.1% or less. It may contain at least one of 1% or less.

7.Hot rolling is performed on the steel slab having the composition described in any one of 1 to 3 above under the condition that the heating temperature is in the austenite single-phase region and the coil winding temperature is 650 or less. After descaling, after cold rolling once or twice including intermediate annealing, finish annealing in ferrite single phase region with 700 or more. Manufacturing method of excellent non-oriented electrical steel sheet.

8. Hot rolling was performed on the steel slab having the composition described in any of the above 1 to 3 under the following conditions: the heating temperature was in the austenite single phase region, and the coil winding temperature was 650: Then, when the Ni content is 0% (no addition) to 1.0 mass%, the hot-rolled sheet is annealed in a ferrite single-phase region of 900 or more or an austenite single-phase region of more than ₃ points of Ac. Ni content exceeds 1.0 mass%, 2.3 mass ⁰ /. In the following cases, it is performed in the austenite single-phase region of 3 points or more of Ac, then, after descaling, cold-rolled once or twice or more including intermediate annealing, and then A method for producing non-oriented electrical steel sheets with excellent magnetic properties and punching accuracy, characterized by performing finish annealing in the phase region.

9. Hot rolling is performed on the slab of 5 or 6 above at a hot rolling heating temperature of 100 000 ^ to 120 000 ° and a hot rolling coiling temperature of 65 O or less. A method for producing a non-oriented electrical steel sheet having excellent strength, magnetic properties, and punching precision, comprising performing cold rolling once or twice including intermediate annealing, and then performing finish annealing. In the method for producing an electromagnetic steel sheet in the above item 9, hot-rolled sheet annealing may be performed after hot-rolling. Further, in the method for producing an electromagnetic steel sheet according to any one of the above items 7, 8, and 9, after the finish annealing, a treatment for providing an insulating film may be performed. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a graph showing the influence of Si content and P content on the relationship between yield strength and punched diameter.

 FIG. 2 is a graph showing the effect of Si content and P content on the relationship between yield strength and punching anisotropy.

 FIG. 3 is a graph showing the influence of the Si content and the P content on the relationship between the average crystal grain size and the punched diameter.

 FIG. 4 is a graph showing the influence of the Si content and the P content on the relationship between the average grain size and the punching anisotropy.

 FIG. 5 is a graph showing the effect of the Si content and the P content on the relationship between the average crystal grain size and iron loss.

 FIG. 6 is a graph showing the influence of the Si content and the P content on the relationship between the average crystal grain size and the magnetic flux density.

 FIG. 7 is a graph showing the effect of Si content and P content on the relationship between iron loss and magnetic flux density.

 Figure 8 is a graph showing the effect of Si and P contents on the occurrence of layered cracks.

 Figure 9 is a graph showing the effect of Si and Ni contents on the occurrence of layered cracks.

 FIG. 10 is a graph showing the effect of Si content and Ni addition on the relationship between P content and punched diameter.

FIG. 11 is a graph showing the effect of Si content and Ni addition on the relationship between P content and punching anisotropy. FIG. 12 is a graph showing the effect of the P content on the relationship between the tensile strength and the magnetic flux density.

 FIG. 13 is a graph showing the relationship between and and high-frequency iron loss.

 FIG. 14 is a graph showing the relationship between the plate thickness and the magnetic flux density. BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, experimental results that led to the present invention will be described in detail. The percentages of the component compositions shown below are all “mass%”.

(Experiment 1)

 First, in order to clarify the relationship between the steel composition of the non-oriented electrical steel sheet and the punching dimensional accuracy, C: 0.0016 to 0.240%, Mn: 0.20 to 0.22%, A1: 0.20%. 0007 ~ 0.0014%, N: 0.0012 ~ 0.0022% and Sb: 0.03%, and the basic composition was the basic composition. The P content was constant at 0.02% and the Si content was 0%. Steel with a range of 03 to 1.49%, and steel with a P content of 0.02 to 0.29% with a constant Si content of 0.10 to 0.11% Was produced in a laboratory. Next, these steel materials were heated at 1100 for 60 rains, hot-rolled to a plate thickness of 2 ram, kept at a uniform temperature equivalent to coil winding of 2 h at 600, and allowed to cool. Then, after hot-rolled sheet annealing at 900 for 60 s, pickling and then cold-rolled to a sheet thickness of 0.5 ram, finish annealing at various temperatures of 700 to 900 ^, and recrystallized grains The particle size of was varied. Thereafter, a sample prepared by applying and baking semi-organic insulating material having an average film thickness of 0.6; / m to the finish annealed plate was prepared and subjected to a punching test. The average crystal grain size was defined as the equivalent circle diameter determined by the Jeffries method by observing a cross section in the thickness direction parallel to the rolling direction.

The punching test was performed using a circular mold having a diameter of 21πιιηψ, and the clearance was set to 8% of the plate thickness. Measure the diameter (inner diameter) of the punched circle in four directions with angles of 0 °, 45 °, 90 °, and 135 ° to the rolling direction, determine the average diameter of the four points, and determine the maximum diameter among the four points. The difference between the diameter and the minimum diameter was measured and used as an index of punching anisotropy. Figures 1 and 2 summarize the results obtained in relation to the yield strength (YP) obtained from tensile test pieces (JIS No. 5) cut out in the rolling direction.

 As is evident from Figs. 1 and 2, the difference in the punching diameter of a soft material with a low YP is large compared to the die diameter, and the punching diameter approaches the die size as the YP rises. Therefore, dimensional accuracy tends to improve. This is considered to be the effect of suppressing the sagging at the time of punching by increasing the strength, as was conventionally known.

 However, it should be noted here that the samples whose strength was adjusted by adding P had excellent dimensions even at the same level of strength compared to conventional magnetic steel sheets whose strength changed due to the change in the amount of Si. It shows high accuracy, and the dimensional difference from the mold is suppressed even in the relatively low YP range (Fig. 1).

 In the case of steel with a varied amount of Si, the punching diameter approaches the die size as the strength increases, but as shown in Fig. 2, the anisotropy represented by the difference between the maximum diameter and the minimum diameter is reduced. It remains large. On the other hand, steel with increased strength by increasing the P content also has improved anisotropy in the punched shape.

 Figures 3 and 4 summarize these relationships in relation to the average grain size of the finish annealed sheet.

 As is evident from Figs. 3 and 4, the steel with the varied amount of Si has poor punching dimensional accuracy and punching anisotropy as the grain size increases, while P is 0.13% or more. The added steel has a good level of punching dimensional accuracy and punching anisotropy even if the grain size is large.

Although the details of the reason why punching dimensional accuracy and punching anisotropy are effectively improved by including P in a certain amount or more are not clear,

(1) In addition to the effect of increasing the strength due to the addition of P and reducing the sag deformation during punching, (2) Addition of an appropriate amount of P, which is known as a brittle element, to the steel has the effect of shortening the fracture limit during punching, and

 (3) The addition of P tends to increase the {100} and uvw> orientations in the texture of the finish-annealed sheet, and this is due to the combined effect of the effect of relaxing anisotropy, etc. thinking. Next, a description will be given of the results of an examination in terms of magnetic characteristics.

 By limiting the content of Si and A1 as much as possible, which improves the core loss but lowers the saturation magnetic flux density, the inventors made the steel whose magnetic flux density was essentially high as a material, and examined the manufacturing conditions and magnetic properties. The relationship was discussed in detail.

 Figure 5 shows the crystal grain size of the finished annealed sheet and iron loss in the commercial frequency range for samples with a steel thickness of 0.5 ram (Wis / 50: value at a frequency of 50 Hz and maximum magnetic flux density of 1.5 T). The results of an investigation on the relationship between and are shown.

 As is evident from the figure, low Si is disadvantageous for iron loss due to reduced electrical resistance, but iron loss varies greatly depending on the crystal grain size, so the grain size should be about 30 / zm or more. It can be seen that low iron loss can be obtained stably. Similarly, when the electric resistance was reduced to a low value of A1, it was also confirmed that setting the particle size to about 30 μπι or more was effective in reducing iron loss.

 However, until now, in the case of non-oriented electrical steel sheets belonging to the low grade of low Si and A1 composition as in the present invention, the average grain size of the finish-annealed sheet is limited to about 15 to 25 / z ra. It was customary. The reason for this is that, as shown in the example of 0.1% Si-0.07% P steel (marked in the figure) in Figs. .

On the other hand, steel with increased P content maintains good punching dimensional accuracy even when the average grain size is about 30 / xm or more. Next, Fig. 6 shows the relationship between the average crystal grain size and the magnetic flux density of each steel type, and Fig. 7 shows the iron loss. The result of examining the relationship between and magnetic flux density is shown. Here, B ₅₀ is a magnetic flux density at a magnetization force of 5000 A / m.

 In the sample added with Si, the iron loss is improved, but the magnetic flux density is greatly reduced. In contrast, the sample to which P is added maintains a high magnetic flux density even after the crystal grains have grown and the iron loss has been improved. By the way, P is an embrittlement element, and when a large amount of P is added as in the present invention, defects such as edge cracks and layer cracks may occur mainly in the cold rolling process. The present inventors investigated this phenomenon diligently, and when the temperature in the slab heating during hot rolling was in the coexistence region of ferrite and austenite, distribution of P occurred between the ferrite grains and the austenite grains, and significant P in the ferrite grains. Segregation of the steel and promoted the embrittlement of steel. In order to prevent such embrittlement, the slab heating temperature for hot rolling in the production of the steel sheet of the present invention should be in the austenite single phase region (or, if possible, the ferrite single phase). is important.

 Since P is a ferrite forming element, it has the effect of reducing the austenite single-phase region near the slab heating temperature. However, in the low Si steel component range, if the slab heating temperature is 1000 to 1200, the austenite It can be single phase. As described above, it became clear that the addition of about 0.1% or more of P to the low Si steel was very effective. Therefore, the active addition of P to steel sheets containing 0.5% or more of Si was studied.

(Experiment 2)

C: 0.0013 to 0.0026, Mn: 0.18 to 0.23%, A1: 0.0001 to 0.0011%, N: 0.0020 to 0.0029% A variety of steels with varying amounts of 0.60 to 2.42 and P amounts of 0.04 to 0.29% were melted, heated at 110 ° C for 60 minutes, and then heated to a sheet thickness of 2 mra. After pickling, the plate was cold rolled to a thickness of 0.50 awake. As a result, depending on the steel composition, A defect occurred in which a layered crack was generated inside the plate parallel to the plate surface. Fig.

See Figure 8.

 When the layered cracked portion was analyzed by mupping using EPMA, it was observed that P was segregated or concentrated in the cracked portion. Therefore, we examined the segregation conditions of P in detail, and found that during hot rolling, the conditions were such that when the steel slab (slab) was heated, it was balanced in the two-phase region of the ferrite and austenite phases. It was found that P was distributed and concentrated.

 That is, in the middle to high Si steel region, the austenite single phase region is further reduced due to the large amount of Si and A1, which are ferrite forming elements, and as a result, the ferrite austenite two phase region tends to be formed at the conventional heating temperature. The problem became clear. When P exceeded 0.26%, laminar cracking occurred under any composition conditions. Therefore, steels with various Si, Mn, AI, and P contents were manufactured at the research facility, and in the temperature range of about 100 to 1200 ^ 0, unbalanced P caused rolling failure. We investigated the conditions that can be controlled to the extent that they do not. The slab ripening temperature described above is a suitable temperature from the viewpoint of stabilizing the precipitation of carbon dioxide, nitride, sulfide and the like existing in the steel.

 First, under the condition that the slab heating temperature is in the austenite single phase region or the ferrite single phase region, segregation due to phase distribution does not occur, so it is considered that layered cracking can be avoided if the P addition amount itself is less than the predetermined amount. According to the above experiment, the amount of P added needs to be about 0.26% or less.

 Therefore, the conditions under which the medium- to high-Si steels become a single austenite phase were investigated first.

 As a result, in steels containing more than 0.5% of Si + Al,

P≤P _A \ where

P _A '= -0.2Si + 0.12Mn-0.32A1 +0.36 (1),

 (Each content of Si, Mn, Al and P is expressed in mass%)

It was found that the temperature was within the austenitic single-phase region when the range was within the range. Therefore, the above article If the condition is satisfied and P≤about 0.26%, embrittlement due to P can be suppressed.

Next, the conditions under which the medium- to high-Si steel becomes a ferrite single phase were investigated. Similarly, when the amount of P added was P≥P _F ,

 Ρρ '= -0.34Si + 0.20Mn-0.54A1 + 0.76 (2),

 (Each content of Si, Mn, Al and P is represented by mass%)

It was found that the range was within the ferrite single phase range. Therefore, even if this condition is satisfied and the content is limited to about 0.26%, embrittlement due to P can be suppressed.

Next, we investigated the conditions for suppressing P segregation when slab heating in the austenite single phase region or ferrite single phase region is difficult. When the distribution of P concentration occurs in the two-phase region of ferrite and austenite, the P concentration in the ferrite phase also becomes the above P _F ′ Force S. As a result of investigation, if this P _F ′ is set to about 0.26 or less, It was found that embrittlement by P could be avoided. When the embrittlement avoidance conditions in the two-phase region and the embrittlement conditions in the ferrite single-phase region are summarized, P ≤ about 0.26%? 1? '^ About 0.26. Summarizing the above relations, embrittlement times 5 ^ matter by the P, in P≤ about 0.2 6% One or become PP _A or P _F, ≤ about 0. 2 6.

 From the above results, if the amount of P added is within about 0.26% and the steel sheet is heated to the austenite single-phase or ferrite single-phase region during hot-rolling heating, layer cracks after cold rolling, etc. In addition, the ferrite / austenite two-phase force B reduces the amount of P distribution to the ferrite phase even under heat conditions.

It has been found that a component system having a relatively high amount of 1 can be produced. Furthermore, even if about 0.1% or more of P is added, a steel with an austenite or ferrite single phase structure in the slab heating temperature range (around 100 to 120 O ^ C) during hot rolling. Various compositions were studied.

 As a result, it was found that the addition of Ni, which is an element suitable for improving magnetic properties and ensuring strength, is also effective in expanding the austenite region near the hot rolling temperature in P-added steel.

(Experiment 3)

 C: 0.0013 to 0.0026%, Mn: 0.18 to 23%, A1: 0.0007 to 0.0013%, N: 0.0014 to 0.0025%, and P: 0.16 to 0. Samples with a basic composition of 18% and a Si content of 0.95 to 2.44% and a Ni content of 0 to 2.20% were rolled to 0.50 thighs as in Experiment 2. Then, the state of occurrence of layered cracks in the obtained cold-rolled steel sheet was investigated. Figure 9 shows the results.

 Cracked without Ni addition 1.1-1.5% Si steel rolls The addition of Ni enables rolling without cracking. On the other hand, in 1.95% Si steel and 2.4% Si steel that could be rolled without Ni addition, cracking may occur due to an increase in Ni, indicating that there is an appropriate region for the effect of Ni.

Extending the above equation taking into account the effect of Ni, in steels containing more than 0.5% of Si + Al, the amount of P added is about 0.26% or less, and

P≤P _A , where

P _A = -0.2Si + 0.12Mn-0.32A1 + 0.05Ni ² + 0.10Ni +0.36 If the range is (1), the slab heating temperature of 1 0 0 to 1 2 0 is austenite In the single-phase region,

P _F ≤about 0.26, but

P _F = -0.34Si + 0.20Mn-0.54A1 + 0.24Ni ² + 0.28Ni +0.76 ≤ P (2) It was found that the degree of enrichment was small, and in each case, embrittlement due to P could be avoided.

In the above two equations, the contents of Si, Mn, Al, P, and Ni are represented by mass%. Shall be. The technical meanings of PF and PA are the same as those of PF and PA.

(Experiment 4)

 The cold-rolled steel sheet rolled to 0.50 thighs in Experiments 2 and 3 was subjected to finish annealing, and then semi-organic insulation with an average thickness of 0.6 m was applied and baked. Punching tests were performed on these samples by the method described in Experiment 1 to investigate the punching diameter and its anisotropy, and the results are shown in FIGS. 10 and 11. From these figures, it can be seen that even with steel containing more than 0.5% of Si + Al, the steel containing P≥0.10% showed excellent punching dimensional accuracy. Here, the addition amount of Ni-added steel was varied between 0.38 and 2.20%.

Fig. 12 shows the relationship between the magnetic flux density _B50 and the tensile strength TS of these samples. Here, TS was determined by the same tensile test as in Experiment 1, and the magnetic flux density was also measured by the method in Experiment 1.

Steels containing about 0.1% or more of P show superior B50-TS balance compared to conventional medium to high Si steel sheets (ie, Si + Al> _0.5 %) . In particular, as the amount of P added increased, TS increased but the magnetic flux density did not decrease, but tended to increase. This is characteristic in that the strengthening of the steel sheet by the addition of alloying elements other than ferromagnetic materials such as S i and A 1, which is usually performed for conventional magnetic steel sheets, is accompanied by a decrease in magnetic flux density.

These characteristics are suitable for motor materials such as Dc brushless motors and reluctance motors, which are required to have high torque, small size, and high speed rotation of motors. Based on the above findings, the conditions for achieving both excellent magnetic flux density and punching dimensional accuracy include the amounts of Si, Al, P, and Ni in the steel, and the average crystal grain of the finish-annealed sheet for low-Si steel. The diameter was specified in the following range. Low Si steel ^ \ Si, Al 1 or 2 types total: about 0.03 ~ 0.5%

Since Si and Al have a deoxidizing effect when added to steel, they are used alone or in combination as deoxidizing agents. To achieve this effect, Si and Al must be used alone or in a total of about 0.03% or more. Also, Si and Al have the effect of increasing the specific resistance and improving the iron loss, but on the other hand, they lower the saturation magnetic flux density, so the upper limit was set to 0.5%. For medium to high Si steels, the sum of one or two types of Si and Al: more than 0.5% to about 2.5%

 When mechanical strength and low iron loss are important together with excellent dimensional accuracy, the total amount of Si + Al can be more than 0.5%. As already mentioned, even in the case of medium to high Si steel, the effect of the addition of P makes it possible to obtain a material with higher punching accuracy and strength / magnetic flux density compared to the conventional low P medium to high Si steel. can get. However, if the total amount of Si + Al exceeds 2.5%, ordinary cold rolling becomes difficult even by the method of the present invention, so the range is more than 0.5% to about 2.5%. %.

P: About 0.10% or more, about 0.26% or less

 P is a particularly important element in the present invention. As has been known, P has a function of adjusting the material hardness by its high solid solution strengthening ability. In particular, low-Si and low-Al steel sheets are relatively soft by nature, but in the present invention, the average grain size needs to be about 30 / m or more to reduce iron loss. There is a possibility that.

P is an essential element for improving the punching property of the steel sheet of the present invention, that is, for suppressing an increase in sagging and burrs due to insufficient strength of the steel sheet. In addition to the ability to increase the strength of the material, the effect of suppressing the total amount of deformation at the time of punching by increasing the breaking limit at the time of punching, and the effect of {100} w> Improve the punching dimensional accuracy by the combined effect of increasing the orientation and improving the anisotropy. In addition, despite the fact that the strength of the steel sheet is increased, it does not lower the magnetic flux density. This effect is also exhibited in medium to high Si steel.

 In order to exhibit these effects, P must be contained in an amount of about 0.10% or more. On the other hand, P is originally a brittle element to steel, and if added excessively, it tends to cause ear cracks and layer cracks, which lowers the manufacturability. In this regard, in the present invention, it is possible to manufacture a high-P-added steel, which has been conventionally difficult, by modifying the manufacturing method or adding Ni. However, if the content exceeds about 0.26%, the production of P-added steel becomes difficult even if the production method of the present invention is used, so the P content is limited to the range of about 0.10 to about 0.26%. did.

Ni: about 2.3% or less (can be added as an option)

 Ni not only has the effect of improving the texture of the steel to increase the magnetic flux density, but also has the effect of increasing the electrical resistance of the steel to reduce iron loss, and has the effect of increasing the strength of the steel by solid solution strengthening. Since it also has the effect of suppressing drooling during punching, it can be added positively.

Since Ni is an austenite-forming element, it has the effect of expanding the austenite region (γ loop in the phase diagram) in the vicinity of the preferred slab heating temperature of 1000 to 1200. In particular, it is effective to increase the operation stability for steels with a composition of Si + Al greater than 0.5%. By utilizing this effect, the rolling instability that can occur when the brittle element P is positively added as in the present invention can be significantly improved. In other words, the point of stable production of high-P steel is to suppress excessive P bias during hot rolling, and to prevent the slab heating temperature from being in the ferrite-no-austenite two-phase region as an effective means. If the sum of the Si content and the A1 content exceeds 0.5%, it is easy to separate into two phases at the slab heating temperature. Occasionally, it becomes possible to form an austenitic single phase. However, when the Ni content exceeds about 2.3%, the transformation start temperature of ferrite (a) → austenite (γ) decreases, and austenite transformation occurs during finish annealing. As a result, the magnetic flux density may be reduced. Also, at a low finish annealing temperature lower than the transformation temperature, it becomes difficult to secure an average grain size of about 30 / ra or more in low Si steel, and iron loss also deteriorates. Therefore, it is assumed that Ni is contained at about 2.3% or less. In addition, when adding Ni, it is preferable to add about 0.5% or more. In low Si steel, the average grain size of the finish annealed sheet: about 30; zm or more, about 80 μηι or less In order to obtain good iron loss characteristics in the low Si, low A1 non-oriented electrical steel sheet of the present invention, As shown in Fig. 5, the average grain size of the finish-annealed sheet must be about 30 // m or more. However, even if the grain size exceeds about 80 / m, no further improvement in iron loss can be expected.In addition, the steel according to the present invention is a transformed steel, and its slip single phase region is suitable for recrystallization annealing. Since the temperature is lower than that of ferritic single-phase steel with a high Si composition, excessive grain growth is disadvantageous in terms of productivity in continuous short-time annealing equipment. / im is the upper limit.

 In addition, in the medium to high Si steel, the alloy has an effect of improving electric resistance by the alloy and the like, and relatively low iron loss is easily obtained. Therefore, the grain size is not particularly limited and may be in a normal range. Generally, it is 20 to 200 / m. Next, the inventors studied a technique for improving magnetic characteristics in a high-frequency range, which has been gaining importance in recent years with the increase in the rotation speed and the number of poles of the motor. As a result, it was found that thickness reduction was effective, and the effect was particularly remarkable in low Si steel. The experiment which led to the result is shown below.

(Experiment 5)

 Figure 13 shows the loss of iron at 400Hz for 0.11% Si—0.18% P steel, 0.95% Si—0.02% P steel and 2.0% Si—0.5 ° / οΑ1 steel. The result of examining the thickness dependency is shown.

As shown in the figure, the high frequency iron loss tends to be improved because the eddy current loss of all samples decreases due to the reduction of the plate thickness. It can be seen that the effect is greater for the low Si steel.

 However, the thickness of non-oriented electrical steel sheets has so far been 0.50 mra, and further reductions in thickness are only applicable to some high-grade grades with high contents of Si and A1, which are specific resistance elements. As a result, there was no product example applied to non-oriented electrical steel sheets with low contents of Si and A1.

 Fig. 14 shows the results of examining the dependence of the magnetic flux density of these materials on the plate thickness.

 As shown in the figure, when the sheet thickness is reduced, the magnetic flux density tends to decrease slightly, but the decrease is negligible, and the low Si steel is much higher at all sheet thicknesses. It has a magnetic flux density. In particular, for applications such as electric vehicle (EV) and hybrid electric vehicle (HEV) drive motors, high-speed rotation type reluctance motors are being studied. In such applications, high magnetic flux density and high frequency Low iron loss property is emphasized, but this can be dealt with by reducing the thickness of a steel sheet of low Si and low A1, which is essentially high in magnetic flux density as shown in the present invention.

 As shown in Fig. 13, the effect of reducing the thickness becomes significant when the thickness is about 0.35 or less, and becomes even more significant when the thickness is about 0.30 mm or less. Since the thinner the sheet, the more effective it is at reducing eddy current loss, no lower limit is set, but the number of man-hours for stacking the core increases and the cost increases, and it is difficult to caulk the laminated core. In the case of general production, the lower limit is preferably about 0.10 mm.

The reasons for limiting the components other than Si, Al, P and Ni in the steel of the present invention will be described below.

 C: 0 to about 0.010%

C is an element that deteriorates the magnetic properties (iron loss) with the passage of time after the steel machine due to the aging effect, and the degree becomes significant when the C content exceeds about 0.010%. Therefore, the C content was limited to 0.010% or less. In addition, as for the aging deterioration characteristics, the smaller the C content, the better. Therefore, in the present invention, the C content is substantially zero. Mouth (analysis limit full) shall be included.

Mn: about 0.5% or less

 n has the effect of fixing S as n S and suppressing embrittlement during hot rolling caused by Fe S. In addition, as the Mn content increases, the specific resistance increases and iron loss is improved. However, on the other hand, an increase in the Mn content causes a decrease in the magnetic flux density, so the upper limit of the Mn content was set to about 0.5%.

S: about 0.015% or less

 S is an unavoidable impurity, and when precipitated as FeS as described above, it not only causes hot embrittlement but also deteriorates grain growth of finely precipitated ^, reducing iron loss. From the viewpoint of, it is advantageous to reduce as much as possible. Here, if the amount of S exceeds about 0.015%, the cost of iron loss deterioration becomes extremely large, so the upper limit was set to about 0.015%. However, on the other hand, S also has the effect of improving the shear profile at the time of punching, so the extent of reduction is determined according to the application.

N: about 0.010% or less

 N is an inevitable contaminant impurity, and when finely precipitated as A1N, it inhibits grain growth and degrades iron loss. Therefore, N was restricted to about 0.010% or less. As described above, the essential component and the suppressing component have been described. In the present invention, the following elements can be appropriately contained as magnetic property improving components.

Sb and / or Sn: about 0.40% or less in total

Sb and Sn are unevenly distributed at grain boundaries, and have the effect of improving magnetic flux density and iron loss by suppressing the generation of {111} oriented recrystallization nuclei from crystal grain boundaries during steel recrystallization. You. In order to obtain this effect, it is desirable to contain about 0.01% or more in total when used alone or in combination. However, even if it is contained excessively, its effect is not satisfied. If the content exceeds 0.40%, embrittlement occurs and cracks occur during cold rolling.Therefore, the content is less than about 0.40% in total when using warworms or in combination. It is desirable to make it. Other secondary contained elements will be described.

 In the present invention, Ca may be contained in a range of about 0.01% or less as an element for effectively trapping S present as an impurity together with Mn as a deoxidizing agent. In addition, to reduce oxidation and nitridation during strain relief annealing, about 0.005% or less of B and about 0.1% or less of Cr can be added.

 In addition to this, the effect of the present invention is not impaired by adding a known element such as Cu or Mo as an element which does not impair the magnetic properties, but the effect of the present invention is not impaired. Preferably, the content is about 0.1% or less.

 With respect to other components, for example, a small amount of carbonitride forming elements such as Ti, Nb, and V is allowed, but it is preferable to keep the iron loss as low as possible. As described above, in medium to high Si, the component is designed to be a single phase of either the austenite phase or the ferrite phase at the slab heating temperature, or it is in the two-phase state of austenite ferrite. In this case, the composition is designed so that the amount of P enriched in the ferrite phase, which tends to enrich P more easily, is suppressed, excessive local segregation of P is suppressed, and a high-P-added steel is produced stably. It can be so.

 Specifically, the excess of P at the slab heating temperature (about 100 to 1200) that is suitable for the precipitation stability of carbides, nitrides, sulfides, etc. present in steel. In order to suppress local segregation,

An index P _A represented by the following formula:

_{P A = -0. 2Si +0.} 12Mn-0. 32A1 +0. Relationship between ^{05Ni 2 + 0. 10Ni + 0. 36} (1) and P content,

P≤PA Or

An index P _F represented by the following formula: ...

_{P F = -0. 34Si +0.} 20Mn-0. 54A1 + 0. 24Ni 2 + 0. 28Ni + 0. 76 (2) is,

P _F ≤about 0.26

 (Si, Mn, Al, Ni, P units are mass%)

Should be fine. Here, PA was obtained by experimentally determining the upper limit of the P content of the austenitic single phase in the temperature range of about 1000 to 1200 for various Si, Mn, Al, and Ni compositions. P _F are those the P content is the lower limit that the ferrite single phase was determined experimentally. Next, the production conditions of the present invention will be elucidated.

 After smelting the molten steel adjusted to the above-mentioned preferable component composition by a converter refining method or an electric furnace melting method, it is formed into a slab by a continuous casting method or an ingot lump rolling method.

 Next, this slab is subjected to hot rolling after heating. Here, in order to stabilize the precipitation of carbides, nitrides, sulfides, and the like existing in the steel, the slab heating is preferably about 100 to 1200. Also, as mentioned above, the phase state during slab heating is extremely important for suppressing excessive local segregation of P.

Since P is a ferrite-forming element, it has the effect of reducing the austenite single-phase region near the slab heating temperature.However, in the case of low-Si steel, within the component range of the present invention, even if the slab heating temperature is about 1000 to 1200, For example, it can be a single phase of austenite. In the case of medium to high Si steel Further, if the component system satisfying the P≤P _A, the slab heating temperature is from about 1000: it can be single-phase austenite in the range of 1200O. Furthermore, medium to high Si

In the component system that satisfies 0.26: ^, the segregation of P in the ferrite phase remains at a level that can avoid embrittlement even in the region where ferrite and austenite coexist. Further, even when the ferrite is heated in the single phase region of ferrite, if the P content is within about 0.26%, it can be produced without layer cracks or the like. In the present invention, the coil winding temperature after hot rolling is also an important point in securing the productivity of high-P steel. That is, if the coil winding temperature is high, iron phosphating (Fe 3 P) is generated during cooling of the coil, and the bendability and rollability of the hot-rolled sheet are reduced. It is desirable to perform the winding at a temperature as low as possible, preferably about 600 ° or less, more preferably about 550 or less. It is also effective to accelerate the cooling of the coil by immersing the coil after winding into a water tank or by ifc-ing the coil. Then, the hot-rolled coil is subjected to cold rolling after descaling by a technique such as pickling, but hot-rolled sheet annealing can be performed to further improve the magnetic properties.

 Here, in a low Si steel in which the total of the Si content and the A1 content is 0.5% or less, it is preferable that the hot-rolled sheet annealing temperature also avoid the ferrite-no-austenite coexistence region (two-phase region). This is because the growth of crystal grains does not easily progress in the annealing in the two-phase region, and improvement in magnetic properties such as magnetic flux density cannot be expected. Hereinafter, the preferred hot-rolled sheet annealing temperature in low Si steel will be described according to the amount of Ni.

 i When the additive-free steel or the Ni content is relatively low (1.0% or less), the non-oriented electrical steel sheet is usually about 900% or more as in the case of hot-rolled sheet annealing.で き る Can be annealed in the light single phase region. In addition, the temperature of the slag can be increased to a single phase region of austenite (preferably about 1050 to 1100) with three or more Ac points. In short, it is important to avoid annealing (especially around 950¾) in the two-phase region, which is the intermediate region between the two.

On the other hand, when the Ni content is relatively high, that is, more than 1.0 to 2.3%, the austenite formation temperature during annealing decreases, so that a two-phase region is obtained even at an annealing temperature of about 900, The magnetic flux density decreases. However, sufficient magnetic flux density cannot be obtained by annealing in the single phase region of ferrite below 900 due to insufficient grain growth. Therefore, the annealing condition of the hot rolled sheet in this component system is limited to the austenite single phase region (preferably about ΙΟδΟ ΙΙΟΟ ^) above the Ac3 point. Limited. In the case of medium to high Si steels, as described above, low iron loss is easily obtained even with fine grains, so that grain growth during annealing is not as important as low Si steels. Therefore, the annealing temperature of the hot-rolled sheet is not particularly limited, but is usually preferably in the range of 700 to 110 ^. Then, after descaling, the obtained coil is rolled once in a cold or warm state, or is subjected to two or more cold (or warm) rolling steps with intermediate annealing to obtain a predetermined thickness. Finish.

 After that, finish annealing is performed. In the case of low Si steel, this finish annealing is performed in the ferrite single phase region of 700: or more. This is because if the final annealing temperature is less than 700, it is difficult to stably grow the average grain size to about 30 m or more, and if austenite grains are formed beyond the ferrite single phase region, the aggregated yarn! ^ Is formed. This is because of deterioration, leading to deterioration of magnetic flux density and iron loss.

 In the case of medium to high Si steel, the grain growth during annealing is not as important as that of low Si steel, as described above.Therefore, the final annealing temperature is not particularly limited, but is usually in the range of 700 to 110. It is preferable that

 The ferrite single-phase temperature range or austenite single-phase temperature range of the hot-rolled sheet and cold-rolled sheet is obtained by heating and water-cooling steel sheets of the same composition in various temperature ranges beforehand using an optical microscope. It can be determined by observing with such as. Alternatively, as another method, it can be estimated in advance from a calculation state diagram obtained by thermodynamic calculation software such as Thermo-Calc ™. After the finish annealing, an insulating coating can be applied in the same manner as a general non-oriented electrical steel sheet. The application method is not particularly limited, but a method of performing a baking treatment after applying the treatment liquid is preferable.

The obtained coil is slit to the required width and dimensions, and then After punching into the shape of the motor stator and rotor, they are laminated and commercialized. Alternatively, in some cases, after punching, it is commercialized after being subjected to strain relief annealing (usually 750 Xl to 2 h).

(Example)

(Example 1)

 Molten steel having the composition shown in Table 1 was smelted and incorporated in a laboratory, and then hot rolled to form a sheet par with a sheet thickness of 30 rara. Then, after heating for 1 min at 60 ° C, the plate was hot-rolled to a thickness of 2 mm, and at 600 at 2 hours for coil winding, and then allowed to cool. Then, after hot-rolled sheet annealing at 950 for 60 s, pickling is performed, then cold-rolled to 0.50 thickness (one-time cold-rolling), and finish annealing at various temperatures of 700 to 900 ^. Thus, the recrystallized grain size was variously changed. In addition, during cold rolling, steel J with a P content exceeding the range of the present invention caused many layered cracks parallel to the sheet surface during cold rolling, and the subsequent processing was stopped and evaluation was not performed .

 Nos. 56 to 59 were cold rolled by hot rolling twice without intermediate annealing at 800 without hot strip annealing.

 Next, samples were prepared by applying a semi-organic insulating film having an average film thickness of 0.6 to the obtained finish-annealed sheet and subjected to various tests.

 The punching test was performed using a circular mold having a diameter of 21ηιπιφ, and the clearance was 8% of the plate thickness. The angle made with the rolling direction is 0. , 45 °, 90 °, 135. The diameter of the circle (inner diameter) in four directions was measured, and the average diameter of the four points was determined. The difference between the maximum diameter and the minimum diameter among the four points was taken as the index of punching anisotropy.

 The magnetic properties were measured by the Epstein method using strip-shaped test pieces cut out to 180 mm x 30 mm so that the angles to the rolling direction were 0 ° and 90 °.

For the yield stress (YP), a tensile test was performed at a speed of lOmm / rain using a JIS No. 5 test piece cut out parallel to the rolling direction, and the upper yield point was adopted. The obtained results are shown in Tables 2 and 3.

Table 1 Composition of steel components (mass%)

Note π Al M on n Q p M α

Number

 A 0.0027 0.03 0.0008 0.21 0.0040 0.02 0.0015 0.030 less 0.001

B 0.0026 0.10 0.0008 0.22 0.0035 0.02 0.0020 0.032 <0.001

C 0.0019 0.53 0.0012 0.22 0.D023 0.02 0.0018 0.030 less 0.001

D 0.0019 0.95 0.0007 0.20 0.0033 0.02 0.0012 0.030 <0.001

E 0.0022 1.48 0.0014 0.21 0.0041 0.02 0.0022 0.033 <0.001

F 0.0016 0.11 0.0015 0.20 0.0074 0.07 0.0019 0.030 less 0.001

G 0.0017 0.11 0.0008 0.21 0.0036 0.13 0.0022 0.031 <0.001

H 0.0023 0.11 0.0011 0.22 0.0022 0.18 0.0014 0.030 <0.001

I 0.0028 0.11 0.0006 0.22 0.0075 0.25 0.0018 0.031 <0.001

J 0.0016 0.11 0.0014 0.21 0.0060 0.29 0.0016 0.032

St'90 / iOdf / X3d LLLZOOm OAV Table 3

In steels A to F (No. 1 to 33, 56, 57) whose P content is less than the proper range of the present invention and whose strength is changed due to changes in the Si content and crystal grain size, the YP As the diameter increases, the punching diameter tends to approach the die diameter. The anisotropy of the punching dimension, expressed by the difference between the maximum diameter and the minimum diameter, is relatively large, about 10 to 20 m. Also, there is a problem that the magnetic flux density decreases as the amount of Si increases.

 On the other hand, according to the present invention, steels G to H containing 0.10% or more of P as a low Si and A1 composition have good punching diameters even when YP is relatively low at 350 MPa or less. ^ Anisotropy of punch size is also small. In terms of magnetic properties, the average grain size of these steel grades was controlled to 30; zra or more (Nos. 37, 38, 39, 44, 45, 46, 47, 51, 52, 53, 53). 54, 59) have stable and low iron loss and high magnetic flux density.

(Example 2)

 Molten steel having the composition shown in Table 4 was smelted in a laboratory and made into a hot-rolled sheet with a thickness of 2 mm in the same manner as in Example 1. After annealing the hot-rolled sheet at 1100 ^ for 30 s After being pickled, it was cold rolled to a thickness of 0.50. Then, finish annealing was performed at various temperatures of 700 or more and in the ferrite single phase region to change the recrystallized grain size in various ways.

 Subsequently, samples coated with the same semi-organic insulating layer as in Example 1 were prepared and subjected to various tests.

 Table 5 shows the obtained results.

Here, steels K to M have been subjected to deoxidation by A1 to reduce Si, and steel N, O, and steel Q, R are melted so that the effect of Ni addition can be evaluated. It was made.

Table 5

Any of the steel compositions satisfying the steel composition of the present invention and having an average crystal grain size of 30 μπι or more have excellent punching dimensional accuracy, low punching anisotropy, and magnetic properties. Was also excellent. In particular, when steel Ν and steel 0 are compared, and steel Q and steel R are compared with each other, a remarkable improvement in magnetic flux density is observed in steel O and steel R to which Ni is added.

(Example 3) Molten steel having the compositions shown in Table 1 (Steel F) and Table 4 (Steel N and Steel O) was smelted in a laboratory and made into a hot-rolled sheet with a thickness of 2 mm in the same manner as in Example 1. After the hot-rolled sheet was annealed at 1100 for 30 s, it was pickled and then cold-rolled to obtain various thicknesses of 0.50 to 0.2 rara. Next, finish annealing was performed at various temperatures of 700 ^ or more and in the ferrite single phase region, and the recrystallized grain size was controlled between 35 and 45 m.

 Next, samples coated with the same semi-organic insulation as in Example 1 were prepared and subjected to various tests. In addition, we investigated high frequency iron loss at 400Hz for these samples.

 The results obtained are also shown in Table 6. Table 6

As the plate thickness is reduced, the iron loss particularly at high frequencies tends to be remarkably improved. Also, the punching dimensional accuracy tends to improve with a decrease in the thickness, but steels N and O satisfying the composition range of the present invention are superior to comparative steel F. Furthermore, the steel of the present invention is excellent in anisotropy of the punched size at any thickness.

(Example 4) Molten steel having the composition shown in Table 7 was smelted in a laboratory and poured into a steel ingot, and was then soaked at 1150 X for 1 hour. And The obtained sheet bar was heated to the temperature (SRT) shown in Table 8 and held for 1 hour, then hot rolled to 2.0 mm, subjected to coil winding at 580 ° C for 1 hour, and allowed to cool. did. After that, except for some steels, hot-rolled sheet annealing was performed under the conditions shown in Table 8. Then, after pickling, they were cold rolled to 0.50 marauders.

 During cold rolling, the workability during cold rolling was evaluated based on the condition of the sheet during cold rolling and the results of observation of the cross-sectional structure after cold rolling. Steel (W, Z, a, c, d, k, and 1) with high P (≥0.10%) and not satisfying the composition range of the present invention, and the composition range satisfying the present invention, When the slab heating (SRT) or hot rolling coiling temperature (CT) is out of the range of the present invention (N (25, 26), many layered cracks are observed parallel to the plate surface, Νο · 5, 19, 25) separated into layers during rolling, making subsequent rolling difficult.These results indicate that it is difficult to carry out industrially stable production, so these samples Was not subjected to the subsequent processing and evaluation.

Next, the cold-rolled sheet was subjected to finish annealing at various temperatures of 700 or more, and then subjected to the same semi-organic insulation as in Example 1, and then subjected to various tests. Here, the strength was measured by cutting a JIS No. ⁵ test piece in the rolling direction and ⁵ mm, pulling it at a pulling speed of 10 ram / s, and evaluating the obtained tensile strength (TS). Table 8 shows the obtained results.

Table 7 3 Steel composition C Si A1 Mn S Ni PN Sb Sn P _A P _A ≥PP _F P _P ≤

No%%%%%%%%%% 0.26 Fixed result

S Comparative steel 0.0018 0.60 0.0010 0.18 0.0041 0.00 0.05 0.0022 <0.001 <0.001 0.261 OK 0.591 NG OK

T Invention steel 0.0011 0.60 0.0011 0.19 0.0033 0.00 0.13 0.0032 <0.001 <0.001 0.262 OK 0.593 NG OK

U Invented steel 0.0014 0.60 0.0006 0.22 0.0028 0.00 0.19 0.0015 <0.001 <0.001 0.266 OK 0.600 NG OK

V Invention steel 0.0032 0.60 0.0005 0.18 0.0032 0.00 0.26 0.0018 <0.001 0.001 0.261 OK 0.592 NG OK w Comparative steel 0.0031 0.63 0.0006 0.19 0.0041 0.00 0.29 0.0021 <0.001 <0.001 0.257 NG 0.585 NG NG

X Comparative steel 0.0011 1.02 0.0010 0.19 0.0032 0.00 0.04 0.0018 <0.001 0.023 0.178 OK 0.451 NG OK

Y Invented steel 0.0011 1.00 0.0011 0.21 0.0032 0.00 0.15 0.0020 <0.001 0.036 0.185 OK 0.461 NG OK z Comparative steel 0.0011 0.98 0.0004 0.19 0.0032 0.00 0.21 0.0022 <0.001 0.025 0.187 NG 0.465 NG NGa Comparative steel 0.0011 1.01 0.0006 0.18 0.0032 0.00 0.25 0.0025 < 0.001 0.032 0.179 NG 0.452 NG NG b Comparative steel 0.0019 1.52 0.0009 0.20 0.0050 0.00 0.04 0.0019 0.018 0.002 0.080 OK 0.283 NG OK c Comparative steel 0.0025 1.54 0.0011 0.19 0.0041 0.00 0.12 0.0012 0.022 <0.001 0.074 NG 0.274 NG NG d Comparative steel 0.0016 1.48 0.0008 0.22 0.0028 0.00 0.17 0.0031 0.023 0.00 0.001 0.090 NG 0.300 NG NG e Invention steel 0.0018 1.63 0.0007 0.18 0.0019 0.00 0.19 0.0026 0.019 1 0.001 0.056 NG 0.242 OK OK f Invention steel 0.0024 1.60 0.0006 0.18 0.0032 0.00 0.25 0.0014 0.022 <0.001 0.061 NG 0.252 OK OK g Comparative steel 0.0008 2.18 0.25 0.20 0.0008 0.00 0.03 0.0018 <0.001 0.035 -0.132 NG -0.076 OK OK h Invention steel 0.0011 2.20 0.26 0.18 0.0004 0.00 0.13 0.0022 0.002 0.036 -0.142 NG -0.092 OK OK i Invention steel 0.0016 2.11 0.25 0.18 0.0013 0.00 0.19 0.002 1 <0.001 0.034 -0.120 NG -0.056 OK OK j Invention steel 0.0017 2.08 0.27 0.19 0.0017 0.00 0.24 0.0035 <0.001 0.032 -0.120 NG -0.055 OK OK k Comparative steel 0.0024 2.11 0.27 0.22 0.0023 0.00 0.29 0.0028 <0.001 0.035 -0.122 NG- 0.059 OK OK

1 Comparative copper 0.0026 1.50 0.0010 0.20 0.0032 0.50 0.18 0.0026 <0.001 0.022 0.146 NG 0.489 NG NG m Invention steel 0.0033 1.45 0.0005 0.19 0.0015 1.09 0.16 0.0021 0.002 0.021 0.261 OK 0.894 NG OK n Invention steel 0.0036 1.56 0.0010 0.19 0.0032 1.57 0.17 0.0019 <0.001 0.021 0.351 OK 1.296 NG OK

0 Inventive steel 0.0038 1.50 0.0006 0.21 0.0022 2.13 0.19 0.0025 <0.001 0.026 0.525 OK 1.978 NG OK

The steels (Nos. 2 to 4, 7, 13, 14, 16 to 18, and 21 to 24) containing at least 0.1% of P as components within the scope of the present invention have excellent punching dimensional accuracy. Is shown. That is, for steels with less than 0.1% of P added (Να1, 6, 10, and 15), the punching diameter tends to improve with the increase of Si + Al content, but Large anisotropy in diameter. On the other hand, it is clear that the steel of the present invention is excellent in both the punching diameter and the anisotropy of the punching diameter. Furthermore, these inventive steels have a magnetic flux density equal to or higher than that of comparative steels with a P content of less than 0.1%. Nevertheless, they have high strength, and have an excellent strength-to-magnetic flux density balance.

(Example 5)

 The molten steel having the compositions shown in Table 4, Steel 溶, Steel Ν and Steel Ο was smelted in a laboratory and then hot rolled to form a sheet par with a sheet thickness of 30 cm. Then, each temperature shown in Table 9

After heating to (SRT) for 60 minutes, it was hot-rolled to a plate thickness of 2 ram, kept at a constant temperature equivalent to coil winding for 1 hour at each temperature (CT) shown in Table 9, and then allowed to cool. After that, except for some steels, hot-rolled sheet annealing was performed for 60 seconds at each temperature shown in Table 9.

 A bending test was performed on the obtained hot-rolled steel sheet at room temperature (at 23). In the bending test, a test piece of 100 rara X 30 sq. Was sampled from the hot-rolled sheet so that the rolling direction became longitudinal, and a repeated bending test with a bending radius of 15 mra was performed according to JIS-C2550. Table 9 shows the number of times until the surface of the hot rolled sheet cracked.

 The structure (phase) during slab heating and hot-rolled sheet annealing was investigated by the following method. After maintaining the sheet par and the hot rolled sheet for a predetermined time (described in Table 9) for a predetermined time (slab heating: 1 hour, annealing: 60 seconds), the structure at the time of heating is frozen by water quenching, and optical The phases were identified by microscopic observation of the yarn. The results are shown in Table 9.

The hot-rolled sheet was pickled and then cold-rolled to a thickness of 0.50 (one-time cold-rolling), and evaluated whether or not cold-rolling failure (lamellar cracking) due to embrittlement occurred. The cold-rolled sheet with no layer cracks was subjected to finish annealing at various temperatures shown in Table 9 and then samples coated with the same semi-organic insulating coating as in Example 1 were prepared for various tests. Provided. Table 9 shows the obtained results.

Table 9

No m Copper composition Remarks SRT slab CT Hot rolled sheet Hot rolled sheet Hot rolled sheet Manufacturability Finishing Grain size Β50 W15 / 50 YP

No (C) Heating (C ⁰ ) Annealing temperature Annealing bending temperature Annealing temperature (μιη) (Τ) (W kg) (MPa) Microstructure (c.) Microstructure Several degrees (c.)

 1 M Invention comparative example 1250 α + 7 520 None 4 Layered crack-----

2 M Invention promotion Invention example 1150 Single phase 520 None-30 〇 800 46.2 1.765 4.47 275

3 M Invention Sale Invention Example 1050 "Single phase 520 None 28 〇. 800 38.2 1.762 4.75 288

4 M Invention steel Comparative example 950 α + V 520 None-5 Layer crack--

5 M Invention promotion Comparative example 1150 Υ Single phase 720 900 Single phase 3 Degradation of bendability 850 45.1 1.762 6.83 288

6 N Invention promotion Invention example 1150 y Single phase 620 900 α ft 17 〇 850 65.2 1.764 4.31 242

7 N Invention Promotion Comparative Example 1150 "Single-Phase 550 960 α + 7 20 850 850 53.8 1.736 4.33 244

8.N invention copper invention example 1150 y single phase 550 1100 γ single phase 22 〇 850 52.1 1.768 4.36 246

9 N Invention penalty Comparative example 1150 γ single phase 500 900a single phase 27 〇 670 16.0 1.766 7.38 345

10 0 Invention promotion Invention example 1100 y single phase 600 1100 γ single phase 26 Ο 800 36.5 1.777 4.12 290

11 0 Invention steel Invention example 1100 y Single phase 600 1000 "Single phase 33 〇 800 38.5 1.780 4.02 286

CD 12 0 Inventive steel Comparative example 1100 y Single phase 550 900 a + y 28 Ο 800 32.6 1.733 4.34 298

13 0 Inventive steel Comparative example 1100 y single phase 550 800 α single phase 24 ο 800 36.8 1.733 4.10 289

When the steel composition of the present invention (low Si steel) satisfies the manufacturing conditions of the present invention (N (2, 3, 6, 8, 10, and 11)), steel sheets can be manufactured without problems despite the addition of high P. The properties were also good.

 On the other hand, when the slab heating temperature of the present invention was in the two-phase region (Ntxl and 4), it was found that cold rolling failure due to embrittlement easily occurred and commercialization was difficult. Also, when the Koino scraping temperature was higher at 650 (Ν5), the workability of the hot rolled sheet was reduced, and the iron loss of the obtained electrical steel sheet was also reduced. Furthermore, when the hot-rolled sheet annealing temperature was in the two-phase region (Nos. 7 and 12), and in steels with more than 1.0 mass% Ni added, hot-rolled sheet annealing was performed in the α single-phase region. With (Να13), the magnetic flux density of the obtained magnetic steel sheet decreased. Furthermore, when the finish annealing temperature was outside the production conditions of the present invention and was not sufficient to make the recrystallized grain size equal to or more than 30 // m (Ν9), the magnetic properties were also deteriorated. Industrial Applicability Thus, according to the present invention, a non-oriented electrical steel sheet having excellent magnetic properties such as high magnetic flux density and low iron loss, high punching dimensional accuracy, and high strength A stable non-oriented electrical steel sheet can be obtained.

 The non-oriented electrical steel sheet of the present invention is used as a core material for various motors, particularly a reluctance motor that requires particularly high dimensional accuracy and a high magnetic flux density, and an embedded magnet type DC brushless motor that requires further material strength. It is most suitable as iron core material.

Claims

The scope of the claims

1. In mass percentage

 C: 0 to 0.010%,

 At least one of Si and A1: 0.03% or more, 0.5% or less in total,

Mn: 0.5% or less,

 P: 0.10% or more, 0.26% or less,

 S: 0.015% or less and

 N: 0.010% or less

And the remainder is composed of Fe and unavoidable impurities, and

 Average grain size: 30 / m or more, 80μπι or less

Non-oriented electrical steel sheet characterized by the following.

2. The steel sheet according to claim 1, wherein the steel sheet further comprises:

 At least one of Sb and Sn: 0.40% or less in total

A non-oriented electrical steel sheet comprising:

3. The steel sheet according to claim 1 or 2, further comprising:

 Ni: 2.3% or less

A non-oriented electrical steel sheet comprising:

4. The steel sheet according to any one of claims 1 to 3, wherein the steel sheet further comprises, by mass percentage, Ca: 0.01% or less, B: 0.005% or less,

 Cr: 0.1% or less, Cu: 0.1% or less

 Mo: 0.1% or less

A non-oriented electrical steel sheet comprising at least one of the following.

5. The non-oriented electrical steel sheet according to any one of claims 1 to 4, wherein the thickness of the steel sheet is 0.35 mm or less.

6. In mass percentage

 C: 0 to 0.010%,

 At least one of Si and A1: over 0.5%, up to 2.5%,

 Mn: 0.5% or less,

 P: 0.10% or more, 0.26% or less,

 S: 0.015% or less,

 N: 0.010% or less, and

 Ni as required: 2.3% or less

And the remainder is composed of Fe and inevitable impurities, and

Satisfies at least one of P≤P _A and P _F ≤0.26,

However,

PA = -0.2Si + 0.12Mn-0.32Al + 0.05Ni ² + 0.10Ni + 0.36 (1)

PF = -0.34Si + 0.20Mn-0.54Al + 0.24Ni ² + 0.28Ni + 0.76 (2) where unit of each element content is mass%

Non-oriented electrical steel sheet characterized by the above-mentioned.

7. The steel sheet according to claim 6, wherein the steel sheet further comprises:

 At least one of Sb and Sn: 0.40% or less in total

A non-oriented electrical steel sheet comprising:

8. The steel sheet according to claim 6 or 7, wherein the steel sheet further comprises:

 Ca: 0.01% or less, B: 0.005% or less,

 Cr: 0.1% or less, Cu: 0.1% or less

Mo: 0.1% or less A non-oriented electrical steel sheet comprising at least one of the following.

9. For a steel slab having the composition described in any one of claims 1 to 4,

 The hot rolling is performed under the condition that the heating temperature is in the austenite single phase region and the coil winding temperature is 650 or less.

 Then, after descaling, after one or two or more cold rollings including intermediate annealing, finish annealing is performed in a ferrite single phase region of 700 or more. Production method.

10. Hot rolling is performed on the steel slab having the composition as defined in any one of claims 1 to 4 under the condition that the heating temperature is in the austenite single phase region and the coil winding temperature is 650 or less. After a while

 If Ni is not added or the Ni content is 1.0 mass% or less, hot-rolled sheet annealing is performed in either the ferrite single-phase region of 900 ^ or more or the austenitic single-phase region of Ac 3 points or more,

 When the Ni content exceeds 1.0 mass% and is 2.3 mass% or less, hot-rolled sheet annealing is performed in the austenite single-phase region with three or more Ac points.

 Next, after descaling, cold rolling is performed once or twice or more including intermediate annealing.

 A method for producing a non-oriented electrical steel sheet, comprising performing finish annealing in a ferrite single phase region of 700 or more.

11 1. Hot rolling is performed on the steel slab having the composition described in any one of claims 6 to 8 under the conditions of a heating temperature of 1000 to 1200 and a coil winding temperature of 650 ^ or less. After a while

 Perform hot rolled sheet annealing as necessary,

Then, after descaling, cold rolling is performed once or twice or more including intermediate annealing. After a while

 A method for producing a non-oriented electrical steel sheet, comprising performing finish annealing.