Technical field
[0001]
　The present invention relates to an electromagnetic steel sheet.
Background technique
[0002]
　Electrical steel sheet or used in a corrosive environment, or is transported. For example, electromagnetic steel plates or used in areas of high temperature and high humidity, or it is marine transportation. At the time of the maritime transport, a large amount of salt comes flying. Therefore, the electrical steel sheet rust resistance is required. Insulating film on the surface of the electrical steel sheet in order to obtain rust resistance is formed. As the insulating film, and a chromate-based insulation coating. Salt-based insulating film chromic acid show excellent rust resistance but hexavalent chromium, which is used as a raw material for chromate-based insulating film having a carcinogenic. Therefore, the development of the insulating coating which can be formed without the use of hexavalent chromium in the raw material has been demanded.
[0003]
　Hexavalent chromium can be formed without using a raw material insulating coating as phosphate-based insulating film, and a silica-based insulating film, and zirconium-based insulating film (Patent Documents 1 to 12). However, these in the insulating film, no rust resistance comparable to salt chromic acid-based insulating coatings were obtained. Although improved rust resistance when thick insulating coatings, weldability and crimping properties as insulating film is thick is reduced.
CITATION
Patent Literature
[0004]
Patent Document 1: JP-B 53-028375 Patent Publication
Patent Document 2: JP-A 05-078855 JP-
Patent Document 3: JP-A-06-330338
Patent Document 4: JP-A 11-131250 JP
Patent Document 5: JP 11-152579 JP
Patent Document 6: JP 2001-107261 Patent Publication
Patent Document 7: JP 2002-047576 JP
Patent Document 8: WO 2012/057168 Patent
Patent Document 9: JP 2002-47576 JP
Patent Document 10: JP 2008-303411 JP
Patent Document 11: JP 2002-249881 JP
Patent Document 12: JP 2002-317277 JP
Summary of the Invention
Problems that the Invention is to Solve
[0005]
　The present invention aims to provide an electromagnetic steel sheet can provide excellent rust resistance hexavalent chromium without the material of the insulating coating.
Means for Solving the Problems
[0006]
　The present inventors have conducted extensive studies to solve the above problems. As a result, the cross section parallel to the thickness direction of the area including the insulation film in the appropriate proportions are metal atoms and Fe atoms contained in the phosphate salt such as Al (e.g., a cross section perpendicular to the rolling direction of the base material) be excellent rust resistance when included in a suitable area fraction is obtained revealed. The formation of such an insulating film, was also revealed that is possible to use a coating solution containing a chelating agent is important.
[0007]
　The present inventors have found that further intensive studies based on these findings, and conceived to aspects of the invention described below.
[0008]
　(1)
　and the base material of the electromagnetic steel,
　the insulating coating formed on the surface of the base material,
　has,
　in the insulation 50 area% or more areas of a cross section parallel to the thickness direction of the film, the following 3 electrical steel sheet characterized in that the condition is satisfied.
　≦ 3 1.8 [Fe] / [P] + .SIGMA.n M [M] / [P] ≦ 3.6 (Condition
　1) 0.6 ≦ .SIGMA.n M [M] / [P] ≦ 2.4 (condition 2)
　0.6 ≦ 3 [Fe] / [ P] ≦ 2.4 ( condition
3) ([Fe] is the ratio of Fe (atomic%), a [P] ratio of P (atomic%), [ M] is Al, a Zn, an individual the proportion of Mg and Ca (atomic%), n M is Al, Zn, individual valence of Mg and Ca.)
[0009]
　(2)
　electrical steel sheet according to the insulation coating, characterized in that it contains an organic resin (1).
Effect of the invention
[0010]
　According to the present invention, since the metal atoms and Fe atoms contained in the phosphate salt such as Al, it is contained in a suitable proportion to 50 area% or more areas of a cross section parallel to the thickness direction of the insulating coating, hexavalent chromium can have excellent rust resistance without using a raw material of the insulating coating. Therefore, it is possible to avoid a decrease in weldability and crimping properties due to thickening of the insulating coating.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011]
[1] Figure 1 is a cross-sectional view showing the structure of an electromagnetic steel sheet according to the embodiment of the present invention.
[Figure 2A] Figure 2A is a diagram showing a TEM observation image of the insulating film formed using a coating solution containing no chelating agent.
[Figure 2B] Figure 2B is a diagram showing a TEM observation image of the insulating film formed by using a coating solution containing a chelating agent.
[Figure 3A] Figure 3A is a sodium chloride concentration is a diagram showing an example of a 1.0% by weight of the rust resistance test results.
[Figure 3B] Figure 3B, sodium chloride concentration is a diagram illustrating an example of a 0.3% by weight of the rust resistance test results.
FIG 3C] Figure 3C, sodium chloride concentration is a diagram illustrating an example of a 0.1% by weight of the rust resistance test results.
[Figure 3D] Figure 3D, sodium chloride concentration is a diagram illustrating an example of a 0.03 mass% of rust resistance test results.
FIG 3E] Figure 3E, sodium chloride concentration is a diagram illustrating an example of a rust resistance test results of 0.01 wt%.
[Figure 4A] Figure 4A is a diagram showing an example of a rust resistance test results of the electromagnetic steel plates forming the insulating film using a coating solution containing no chelating agent.
[Figure 4B] Figure 4B is a diagram showing an example of a rust resistance test results of the electromagnetic steel plates forming the insulating film using a coating solution containing a chelating agent.
FIG. 5 is a schematic drawing illustrating the analytic results of the composition of the insulating coating.
DESCRIPTION OF THE INVENTION
[0012]
　Hereinafter, with reference to the accompanying drawings, it will be described in detail embodiments of the present invention. Figure 1 is a cross-sectional view showing the structure of an electromagnetic steel sheet according to the embodiment of the present invention.
[0013]
　The electrical steel sheet 1 according to the embodiment of the present invention, as shown in FIG. 1, includes base member 2, and the insulating film 3 formed on the surface of the base 2 of electrical steel. Base material 2 has a composition suitable for grain-oriented electrical steel sheet or non-oriented electrical steel sheet.
[0014]
　50 area% or more areas of the cross section parallel to the thickness direction of the insulating coating 3, the following three conditions (Condition 1, Condition 2 and Condition 3) is satisfied. Here, [Fe] is the ratio of Fe (atomic%), [P] is the fraction of P (atomic%), [M] is Al, Zn, Mg, Ca, Sr, Ba, Ti, Zr , V, Mo, W, a discrete proportion of Mn and Ni (atomic%), n M is Al, Zn, Mg, Ca, Sr, Ba, Ti, Zr, V, Mo, W, Mn and Ni it is an individual of valence. Thus, the proportion of Al (atomic%) and valence respectively [Al] and n Al , Zn ratio (atomic%) and valence respectively [Zn] and n Zn , the proportion of Mg (atomic%) and valence each [Mg] and n Mg , Ca ratio (atomic%) and valence respectively [Ca] and n Ca , the ratio of Sr (atomic%) and valence respectively [Sr] and n Sr , the percentage of Ba (atomic%) and valence respectively [Ba] and n Ba , Ti ratio (atomic%) and valence respectively [Ti] and n Ti , the ratio of Zr (atomic%) and valence respectively [Zr] and n Zr , the ratio of V (atomic%) and the number of the respective valence [V] and n V , the proportion of Mo (atomic%) and valence respectively [Mo] and n Mo , the ratio of W (atomic%) and valence, respectively [W] and n W , the ratio of Mn (atomic% ) And valence respectively [Mn] and n Mn , Ni ratio (atomic%) and valence respectively [Ni] and n Ni expressed and, .SIGMA.n M [M] / [P] is, n Al [Al ] / [P], n Zn [Zn] / [P], n Mg [Mg] / [P], n Ca [Ca] / [P], n Sr [Sr] / [P], n Ba [Ba ] / [P], n Ti [Ti] / [P], n Zr [Zr] / [P], n V [V] / [P], n Mo [Mo] / [P], n W [W ] / [P], n Mn [Mn] / [P] and n Ni equal to the sum of [Ni] / [P]. The following may represent Al, Zn, Mg or Ca, or any combination thereof in M. 　≦ 3 1.8 [Fe] / [P] + .SIGMA.n M [M] / [P] ≦ 3.6 (Condition 　1) 0.6 ≦ .SIGMA.n M [M] / [P] ≦ 2.4 (condition 2) 　0.6 ≦ 3 [Fe] / [ P] ≦ 2.4 ( condition 3)

[0015]
　The region that satisfies the conditions 1 to 3 described above, P, M and Fe are included in each appropriate amount. Details will be described later, the region P, M and Fe are included in each appropriate amount, than the insulating film included in conventional electromagnetic steel sheets it is dense, has excellent rust resistance. Therefore, according to the electrical steel sheet 1, it is possible to obtain the hexavalent chromium without the material of the insulating coating 3, an excellent rust resistance without reducing the weldability and crimping properties.
[0016]
　Area ratio of 3 satisfying area of the, for example, can be determined as follows. Transmission electron microscope from the electromagnetic steel sheet (transmission electron microscope: TEM) Prepare sample, [P] at a plurality of measurement points using TEM, the measures the [Fe] and [M]. Measurement is carried out by points 10 along the three scan lines perpendicular to the surface of the electrical steel sheet (rolled surface). The spacing between the scanning lines is set to 1000 nm, within each scan line, equidistantly 11 divides the distance from the surface of the scanning line and the insulating film to the interface between the base material, ten division points of the internal insulation coating and measurement points. Measurement interval within the scan line is dependent on the thickness of the portion located is the scanning line of the insulating coating, for example, approximately 40 nm ~ 60 nm. Then, 3 of each measurement point [Fe] / [P] and .SIGMA.n M calculates the [M] / [P], then calculates a ratio of 3 satisfy the condition among the measurement points in total 30 (%), the to rate the area ratio of 3 satisfying region of the and (area percent).
[0017]
　Next, a method for manufacturing the electrical steel sheet 1. In this way, by applying a polyvalent metal phosphate containing M, a coating solution comprising a chelating agent and water to the base material of the electromagnetic steel, baking. The water, the total concentration of Ca ions and Mg ions used as the 100ppm or less. The polyvalent metal phosphate, aluminum primary phosphate, the first zinc phosphate, the first magnesium phosphate and a first calcium phosphate are exemplified. Hereinafter, aluminum phosphate, zinc phosphate, magnesium phosphate, calcium phosphate shows a first aluminum phosphate respectively, the first zinc phosphate, magnesium primary phosphate, the first calcium phosphate.
[0018]
　Terminal ends of phosphate during the baking of the coating liquid insulation coating is formed by crosslinking in dehydration condensation reaction. As Scheme dehydration condensation reaction, it is exemplified as follows. Here, the chelating agent "HO-R-OH", describes a metal "M".
　P-OH + HO-P → P-O-P ( chemical formula
　1) P-OH Tasu HO-P Tasu HO-R-OH ￫ P-O-R-O-P (chemical formula
　2) P-OH Tasu HO-P Tasu HO-R-OH Tasu M
　　　　　　　　　　　￫ P- O-M-O-R- O-P ( chemical formula
　3) P-OH Tasu HO-P Tasu HO-R-OH Tasu 2M
　　　　　　　　　　　￫ P-O-M-O-R-O-M-O-P (chemical formula 4)
[0019]
　On the other hand, it consists of a polyvalent metal phosphate, and water, if the coating liquid does not contain a chelating agent is used, although the reaction of Formula 1 occurs, no reaction of Formula 2 to Formula 4. Therefore, when the coating solution containing a chelating agent is used, than if the coating liquid does not contain a chelating agent is used there are many cross-linking points in the insulating film, a high rust resistance can be obtained. The number of the more bonds of the chelating agent is more crosslinking points is large, a higher rust resistance can be obtained.
[0020]
　The chelating agent, for example, oxycarboxylic acid, a dicarboxylic acid or phosphonic acid-based chelating agent used. As oxycarboxylic acid chelating agent, malic acid, glycolic acid and lactic acid are exemplified. As dicarboxylic acid chelating agent, oxalic acid, malonic acid and succinic acid. The phosphonic acid chelating agent, an amino trimethylene phosphonic acid, hydroxy ethylidene mono acid and Hiroki shea diphosphonic acid.
[0021]
　The amount of the chelating agent included in the coating solution is 1% by mass to 30% by weight, based on the weight of the insulation coating after baking. Since the coating solution containing phosphate salt is acidic, it does not end the drying of the coating liquid, and, while the coating liquid is held in the acidic and Fe from the base material is eluted into the coating liquid. Then, Fe is excessively eluted, exceeds the reaction threshold of the chelating agent, are generated iron phosphate and iron hydroxide, no insulating coating which satisfies the conditions 1 to 3 is obtained. Such behavior amount of the chelating agent is remarkable when less than 1% by weight. Therefore, the amount of chelating agent is 1 mass% or more with respect to the mass of the insulating film after baking. On the other hand, the amount of chelating agent is in the than 30 wt%, phosphate in the coating solution is less than 70 mass%, no sufficient heat resistance can not be obtained in the insulating coating. Therefore, the amount of chelating agent is less than 30% by weight, relative to the weight of the insulation coating after baking.
[0022]
　Although chelating agents are active compounds, energetically become stable upon reaction with metal, not exhibit sufficient activity. Therefore, to maintain a high activity of the chelating agent, a metal other than the metal contained in the phosphate salt is not reacting with the chelating agent prior to baking of the coating liquid is completed. Therefore, it is preferable that low concentrations of highly reactive metal ions with water chelating agent. Such metal ions, Ca ions and Mg ions are exemplified. The total concentration of Ca ions and Mg ions in 100ppm exceeds, decreases the activity of the chelating agent. Therefore, the total concentration of Ca ions and Mg ions are at 100ppm or less and preferably 70ppm or less. The less well Ca ions and Mg alkaline earth metal ions other than ion.
[0023]
　Chelating agent has a hydroxyl group at a terminal, hydroxyl groups easy to take the association state (hydrogen bond) represented by the Chemical Formula 5.
　R-OH ··· O = R (chemical formula 5)
[0024]
　When the hydroxyl of the degree of association of the chelating agent (the degree of hydrogen bonding) is high, the crosslinking reaction hardly occurs represented by Formula 2 to Formula 4. Therefore, application of the coating solution is preferably performed as the degree of association is as small as possible. For example, when performing coating using a roller (roll coating) is a shear force imparted to the coating solution, it is preferable to apply the coating solution while reducing the degree of association of the chelating agent. The diameter of the roller is reduced, and, by increasing the moving speed of the base material, it is possible to impart a proper shearing force to solve the associated state. For example, it is preferable that a diameter of more than 60 m / min the moving speed of the base material with the following roller 700 mm, that the moving speed of the base material to 70m / min or more using the following roller 500mm diameter more preferable.
[0025]
　Baking of the coating solution is performed at temperatures above 250 ° C., the temperature of the base material, for example, Atsushi Nobori rate of about 30 ° C. from room temperature to 100 ° C. (first heating rate) and 8 ° C. / sec or more at the time of application, heating rate from 0.99 ° C. to 250 ° C. (second heating rate) lower than the first heating rate. Temperature during coating is equal to the temperature of substantially the coating solution.
[0026]
　Progress meeting the foregoing chelating agents, it does not occur if there are no fluidity of the coating solution. Therefore, in order to make the degree of association as low as possible, the first heating rate up to the boiling point of water (100 ° C.) is preferably high. In a less than 1 heating rate 8 ° C. / sec, since the increased association of the chelating agent is rapidly during warm, the crosslinking reaction hardly occurs, represented by Formula 2 to Formula 4. Therefore, the first heating rate is set to 8 ° C. / sec or more.
[0027]
　Degradation and volatilization of the crosslinking reaction and a chelating agent of the phosphate salt and a chelating agent of Formula 1 to Formula 4 occurs in a temperature range of 0.99 ° C. - 250 ° C.. Therefore, by decreasing the second heating rate from 0.99 ° C. to 250 ° C., it can promote the crosslinking reaction while suppressing the degradation of the chelating agent. However, reduction of the rate of temperature rise can lead to reduced productivity. On the other hand, the crosslinking reaction of the chelating agent varies depending on the degree of association of the above-mentioned chelating agents. Therefore, the first heating rate is increased, if reducing the degree of association of the chelating agent, increasing the second heating rate, it is possible to accelerate the crosslinking reaction between the phosphate salt and a chelating agent . On the other hand, the first heating rate is small and the degree of association of the chelating agent is large, unless lower second heating rate accordingly, sufficiently advanced the crosslinking reaction of the chelating agent and the phosphate salt it can not be. The study of the present inventors, and the first heating rate 8 ° C. / sec or more, if the second heating rate is lower than the first heating rate, phosphate salt and chelate according to degree of association of the chelating agent crosslinking reaction between agent proceeds, it has been found that excellent rust resistance can be obtained. However, if the second heating rate is excessively large, for example in 18 ° C. / sec greater, even first heating rate 8 ° C. / sec or more, crosslinking does not sufficiently complete, excellent rust resistance can not be obtained. Therefore, the second heating rate is set to 18 ° C. / sec or less. On the other hand, the second heating rate is higher productivity is lowered low, it becomes significant at less than 5 ° C. / sec. Therefore, the second heating rate is preferably between 5 ° C. / sec or more.
[0028]
　It is possible to manufacture the electrical steel sheet 1 through the coating and baking of the coating liquid to the base material of such an electromagnetic steel.
[0029]
　The coating solution may contain an organic resin. The organic resin contained in the coating liquid comprises an action to suppress the wear of the punching die. Thus, by using a coating solution containing an organic resin, punching of the electrical steel sheet is improved. The organic resin is preferably used as water-dispersible organic emulsion. When water dispersible organic emulsion is used, Ca ions contained therein, alkaline earth metal ions such as Mg ions is preferably as small as possible. As the organic resin, an acrylic resin, an acrylic styrene resin, alkyd resin, polyester resin, silicone resin, fluorine resin, polyolefin resins, styrene resins, vinyl acetate resins, epoxy resins, phenolic resins, urethane resins and melamine resins.
[0030]
　Next, the operation of the chelating agent.
[0031]
　The present inventors have found that in order to clarify the effect of the chelating agent, the insulating coating of the section formed using a coating solution containing no insulating film and the chelating agent was formed using a coating solution containing a chelating agent, TEM It was observed using. At this time, using aluminum phosphate as a polyvalent metal phosphate contained in the coating liquid. In this observation, a cross-section of the electrical steel sheet insulating coating formed by processing with a focused ion beam, using a JEM-2100F manufactured by JEOL Ltd. as a TEM, the accelerating voltage is 200 kV. Figure 2A, shows a TEM observation image of the insulating film formed using a coating solution containing no chelating agent, in Figure 2B, showing a TEM observation image of the formed insulating film using a coating solution containing a chelating agent.
[0032]
　As shown in FIG. 2A, the insulating film formed using a coating solution containing no chelating agent, mainly two kinds of regions where the composition is significantly different was observed. On the other hand, as shown in FIG. 2B, the insulating film formed by using a coating solution containing a chelating agent, mainly one type of area change is small in the composition was observed. Although details will be described later, two kinds of one region is a region mainly composed of P and Al shown in FIG. 2A (hereinafter, sometimes referred to as "Al-rich region"), and the other main P and Fe regions whose components (hereinafter sometimes referred to as "Fe-rich region") was. The composition of the area change of the composition is small as shown in FIG. 2B, it was intermediate in composition between the composition of the composition and Fe-rich region of the Al-rich region.
[0033]
　The present inventors focused on the differences from the above TEM observation image, the area between the composition of the composition of the composition and Fe-rich region of the Al-rich region (hereinafter sometimes referred to as "intermediate composition region") is , considered to contribute greatly to the improvement of rust resistance of the insulating coating, was examined in detail these relationships.
[0034]
　Here will be described an evaluation method for rust resistance.
[0035]
　As a test for evaluating the rust resistance of the electrical steel sheet, salt spray test stipulated in the wet test and JIS Z 2371 is specified in JIS K 2246 are exemplified. However, corrosive environments in these tests is greatly different from the corrosive environment, such as rust caused in the magnetic steel sheets, necessarily, it can not be said that the rust resistance of the electrical steel sheet can be properly evaluated.
[0036]
　Accordingly, the present inventors have examined how you can properly evaluate the rust resistance in corrosive environments, such as rust electrical steel sheet is produced. As a result, it was found that the rust resistance can be suitably evaluated by the following method. In this way, the droplets of aqueous sodium chloride solution having a different concentration on the surface of the electrical steel sheet having an insulation coating is dried by attaching each 0.5 [mu] l, temperature of 50 ° C., a relative humidity RH of 90% constant temperature and humidity electromagnetic steel plates to hold 48 hours to an atmosphere. It may be used thermo-hygrostat. Thereafter, to confirm the presence or absence of rust, to identify the concentration of sodium chloride rust in the electrical steel sheet does not occur. Then, to evaluate the rust resistance based on the concentration of sodium chloride rust is not generated.
[0037]
　That is, in this way, electromagnetic steel sheets are exposed to a humid atmosphere after deposition and drying of the droplets of aqueous sodium chloride solution. Such processes, storage, transportation and adhered salt on the surface of the electrical steel sheet during use, that then salt humidity rises to is deliquescent, similar to a corrosive environment where electromagnetic steel plates are exposed . Higher concentration of sodium chloride is high, the amount of sodium chloride remaining after drying is often prone to rust. Accordingly, performs observation while the concentration of the aqueous sodium chloride solution stepwise decreased, the concentration of rust is not generated (hereinafter sometimes referred to as "limit sodium chloride concentration") if identifying, on the basis of this limit concentration of sodium chloride , it is possible to evaluate the rust resistance in corrosive environments in which the electromagnetic steel sheets are actually exposed quantitatively.
[0038]
　Figure 3A ~ FIG 3E, an example of a test result by the method. In this test, the concentration of sodium chloride, 1.0 wt% (FIG. 3A), 0.3 wt% (FIG. 3B), 0.1 wt% (Fig. 3C), 0.03 wt% (Fig. 3D) or 0 was .01% by weight (Fig. 3E). Then, as shown in FIG. 3A ~ Figure 3E, the concentration of sodium chloride is 1% by mass, 0.3% by weight, rust was confirmed in the case of 0.1 wt% or 0.03 wt%, the concentration of sodium chloride There rust was not observed in the case of 0.01 mass%. Therefore, limit the sodium chloride concentration of the electrical steel sheet is 0.01 wt%. The present inventors have also exceeded the retention time in the atmosphere of constant temperature and humidity is 48 hours, I am sure that such rust situation hardly changes.
[0039]
　Figure 4A, shows an example of the test results by the above method for electrical steel sheet to form an insulating film using a coating solution containing no chelating agent, in Figure 4B, an insulating film using a coating solution containing a chelating agent an example of a test result by the method for forming the electromagnetic steel sheets. Also it includes phosphoric acid as aluminum polyvalent metal phosphate salt to any of the coating solution. In the electromagnetic steel plates forming the insulating film using a coating solution containing no chelating agent, as shown in FIG. 4A, the concentration rust was observed when using a 0.03 mass% aqueous sodium chloride solution. On the other hand, in the electromagnetic steel sheets forming the insulating film using a coating solution containing a chelating agent, as shown in FIG. 4B, the concentration rust is not confirmed even in the case of using a 0.2 wt% aqueous sodium chloride solution.
[0040]
　Thus, in the case of forming an insulating film by using a coating solution containing a chelating agent, than the case of forming the insulating film using a coating solution containing no chelating agent, high limit sodium chloride concentration, excellent rust resistance can be obtained.
[0041]
　The present inventors have included the order to elucidate the structure of the insulating film formed by using a coating solution containing a chelating agent, energy dispersive X-ray spectrometer (JEOL Ltd. of TEM (JEM-2100F) JED -2300T) was performed using analysis of intermediate composition region contained in the insulating film. In this analysis, the diameter is measured composition at a plurality of locations of 1 nm, the proportion of P in the point (atomic%), the proportion of Fe (atomic%), obtains the ratio of Al (atomic%), from these values ​​3 was calculated [Fe] / [P] and 3 [Al] / [P]. The results are shown in FIG. 5 shows, for reference, 3 in the Al-rich region and the Fe-rich region contained in the insulating film formed using a coating solution containing no chelating agent [Fe] / [P] and 3 [Al] / [ P] is also shown. In Figure 5, ● indicates the measurement results of the insulating coating formed by using a coating solution containing a chelating agent, shows the measurement results of insulation coating ◆ was formed using a coating solution containing no chelating agent.
[0042]
　As shown in FIG. 5, the insulating film formed by using a coating solution containing a chelating agent (●), are conditions 1 to 3 was filled with all the measurement points. On the other hand, the insulating film formed using a coating solution containing no chelating agent (◆), was not more than one conditions 1 to 3 is satisfied in most measurement points. This trend is not only aluminum phosphate, zinc phosphate, magnesium phosphate, calcium phosphate, strontium phosphate, barium phosphate, titanium phosphate, zirconium phosphate, vanadium phosphate, molybdenum phosphate, phosphorus acid tungsten, also manifested in the manganese phosphate and nickel phosphate.
[0043]
　From the above, it is apparent that the region satisfying the conditions 1 to 3 contributes to rust resistance. Then, the conditions 1 to 3 in 50 area% or more of the area of ​​the cross section parallel to the thickness direction of the insulating coating 3 according to the embodiment of the present invention are satisfied. Therefore, according to the electrical steel sheet 1, it is possible to obtain an excellent rust resistance. The ratio of the area where conditions 1 to 3 are satisfied is less than 50 area%, it is impossible to obtain a sufficient rust resistance.
[0044]
　50 area% or more areas of the cross section parallel to the thickness direction of the insulating coating 3, it is preferable that one or more of of the conditions 4 to condition 6 below holds.
　≦ 3 2.1 [Fe] / [P] + .SIGMA.n M [M] / [P] ≦ 3.2 (Condition
　4) 0.6 ≦ .SIGMA.n M [M] / [P] ≦ 1.7 (condition 5)
　0.9 ≦ 3 [Fe] / [ P] ≦ 2.1 ( condition 6)
[0045]
　According to the electromagnetic steel sheet 1 according to this embodiment, it is possible to obtain an excellent rust resistance hexavalent chromium without the material of the insulating coating 3. For example, electromagnetic steel sheets 1 also at high airborne under salinity environments such as during sea transport, also exhibit sufficient rust resistance in a high temperature and high humidity environment corresponding to the subtropical or tropical. It is not necessary to form a thick insulating film 3, can avoid a decrease in weldability and crimping properties.
[0046]
　The above embodiments are all merely illustrate concrete examples of implementing the present invention, in which technical scope of the present invention should not be limitedly interpreted. That is, the present invention is its technical idea or without departing from the essential characteristics thereof, can be implemented in various forms.
Example
[0047]
　Next, a description will be given of an embodiment of the present invention. Conditions in examples are an example of conditions adopted for confirming the workability and effects of the present invention, the present invention is not limited to this single example of conditions. The present invention does not depart from the gist of the present invention, as long as they achieve the object of the present invention, it is capable of adopting various conditions.
[0048]
　The present inventors have found that phosphate salts shown in Table 1, a chelating agent, to prepare a coating solution composed of an organic resin and water, which was baked was applied to both surfaces of the base material of the electromagnetic steel. The total concentration of Ca ions and Mg ions contained in the water (ion total concentration) is also shown in Table 1. Conditions and baking conditions of the coating are also shown in Table 1. The first heating rate is heating rate from 30 ° C. to 100 ° C., the second heating rate is temperature increase rate up to 150 ℃ ~ 250 ℃. Preform comprises 0.3 wt% to Si, the thickness of the preform was 0.5 mm. Sample No. In 23, for reference, to form an insulating film with a chromate in place of phosphate.
[0049]
[Table 1]

[0050]
　It was then evaluated for analysis and rust resistance and weldability of the composition of the insulating coating.
[0051]
　Analysis of the composition of the insulating coating, to prepare a TEM sample from the electromagnetic steel sheet, [P] at measurement points 30 for each sample using a TEM, was measured [Fe] and [M]. The measurement was carried out by 10 points along the three scan lines perpendicular to the surface of the electrical steel sheet (rolled surface). The spacing between the scanning lines is set to 1000 nm, within each scan line, equidistantly 11 divides the distance from the surface of the scanning line and the insulating film to the interface between the base material, ten division points of the internal insulation coating was the measurement point. Measurement interval within the scan line depends on the thickness of the portion of which are positioned the scanning line of the insulating coating was approximately 40 nm ~ 60 nm. Then, 3 [Fe] / [P ] and .SIGMA.n M calculates the [M] / [P], and calculating the ratio of 3 satisfy the condition of the conditions 1 to 3 (%) among the measurement points 30. The results are shown in Table 2. Table 2, .SIGMA.n between 3 satisfy all measurement points in each sample M indicates the average value of [P].[M] Underlined in Table 2 indicates that the value is out of range of the present invention.
[0052]
　In the evaluation of the rust resistance, to prepare a test piece from the electromagnetic steel plates, a drop of aqueous sodium chloride solution having a different concentration and dried to adhere by 0.5μl on the surface of the specimen, temperature of 50 ° C., relative humidity RH is a specimen to an atmosphere of 90% constant temperature and humidity was maintained for 48 hours. The concentration of sodium chloride aqueous solution, 0.001 mass%, 0.01 mass%, 0.02 mass%, 0.03 mass%, 0.10 mass%, 0.20 mass%, 0.30 mass% and 1 was 2.0 mass%. Thereafter, to confirm the presence or absence of rust was identified limitations sodium chloride (NaCl) concentration of each specimen. The results are also shown in Table 2.
[0053]
　In the evaluation of weldability, a welding current and 120A, La-W a (2.4mmφ) used as an electrode, the gap and 1.5 mm, the flow rate of the Ar gas 6l / min, a clamping pressure 50 kg / cm 2 as They were welded at different welding speed. Then, to identify the maximum welding speed which blowholes are not generated. The results are also shown in Table 2.
[0054]
[Table 2]

[0055]
　As shown in Table 2, the samples are within the scope of the present invention No. 6 ~ No. 8, No. 11, No. 14 ~ No. In 21, both 0.10 wt% or more limitations sodium chloride concentration and 100 cm / min welding speed is obtained. That is, it provides excellent rust resistance and weldability.
[0056]
　Sample No. 1 ~ No. 5, No. 9 ~ No. 10, No. 12 ~ No. 13, No. 22, No. 24 ~ No. In 27, the limit concentration of sodium chloride or not more than 0.03 mass%, the welding speed is or was 50 cm / min. In other words, rust resistance or weldability or both is low.
Industrial Applicability
[0057]
　The present invention is, for example, can be used in industrial application of the manufacturing industry and electrical steel sheet of the electromagnetic steel sheets.

[Claim 1]
　And the base material of the electromagnetic steel,
　and an insulating film formed on the surface of the base material
　has,
　the 50 area% or more areas of the cross section parallel to the thickness direction of the insulating coating, met the following three conditions electrical steel sheet characterized in that it is.
　≦ 3 1.8 [Fe] / [P] + .SIGMA.n M [M] / [P] ≦ 3.6 (Condition
　1) 0.6 ≦ .SIGMA.n M [M] / [P] ≦ 2.4 (condition 2)
　0.6 ≦ 3 [Fe] / [ P] ≦ 2.4 ( condition
3) ([Fe] is the ratio of Fe (atomic%), a [P] ratio of P (atomic%), [ M] is Al, Zn, Mg, Ca, a Sr, Ba, Ti, Zr, V, Mo, W, each ratio of Mn and Ni (atomic%), n M is Al, Zn, Mg, Ca, sr, a Ba, Ti, Zr, V, Mo, W, each valence of Mn and Ni.)
[Claim 2]
　Electrical steel sheet according to claim 1, wherein the insulating coating, characterized in that it contains an organic resin.