KR101389248B1 - Manufacturing method for grain-oriented electromagnetic steel sheet - Google Patents

Abstract

This invention hot-rolls steel of predetermined | prescribed composition containing Ti: 0.0020 mass%-0.010 mass% and / or Cu: 0.010 mass%-0.50 mass%, and obtains a hot rolled sheet steel. The hot rolled steel sheet is annealed to obtain an annealed steel sheet. The cold rolled steel sheet is cold rolled to obtain a cold rolled steel sheet. The decarburization annealing of the cold rolled steel sheet is performed at a temperature of 800 ° C to 950 ° C to obtain a decarburization annealing steel sheet. Subsequently, nitriding treatment of the decarburization annealing steel sheet is performed at 700 占 폚 to 850 占 폚 to obtain a nitrided steel sheet. The finish annealing of the nitrided steel sheet is performed.

Description

MANUFACTURING METHOD FOR GRAIN-ORIENTED ELECTROMAGNETIC STEEL SHEET}

This invention relates to the manufacturing method of the grain-oriented electromagnetic steel sheet which aimed at suppressing the variation of a magnetic characteristic.

A grain-oriented electromagnetic steel sheet is a steel sheet which contains Si and whose orientation of crystal grains is highly integrated in the {110} <001> orientation, and is used as a material such as a winding iron core of a stationary induction machine such as a transformer. Azimuth control of crystal grains is performed using an abnormal grain growth phenomenon called secondary recrystallization.

The following two methods can be mentioned as a method for controlling the secondary recrystallization. One heats a steel piece to the temperature of 1280 degreeC or more, makes a fine precipitate called an inhibitor almost completely solid, and then performs hot rolling, cold rolling, and annealing, and precipitates a fine precipitate at the time of hot rolling and annealing. The other is hot rolling, cold rolling, decarburization annealing, nitriding and finishing annealing after heating the steel slab to a temperature of less than 1280 ° C., and AlN, (Al, Si) N, etc. as an inhibitor during nitriding treatment. To precipitate.

By the way, in view of recent CO ₂ emission reduction, it is desired to shorten the time required for decarburization annealing in the production process of the grain-oriented electromagnetic steel sheet. For this reason, examination is made about using the slab with low C content.

However, with the decrease in the C content of the slab, the variation (magnetic characteristic deviation) of the magnetic properties depending on the site becomes significant after the finish annealing performed in the coiled state.

Japanese Patent Laid-Open No. 3-122227 Japanese Patent Laid-Open No. 11-323437 Japanese Patent Laid-Open No. 6-256847 Japanese Patent Publication No. 2001-515540 Japanese Patent Laid-Open No. 2000-199015 Japanese Patent Laid-Open No. 2007-254829

An object of this invention is to provide the manufacturing method of the grain-oriented electromagnetic steel sheet which can suppress the dispersion | variation of a magnetic characteristic.

The variation in the magnetic properties after the finish annealing as described above was found to be particularly remarkable when the C content was 0.06 mass% or less, and further 0.048 mass% or less. Although the cause of the variation of the magnetic properties after the finish annealing is not clear, it is considered that the grains do not grow uniformly during the finish annealing even when the grains are uniformly seen before the finish annealing. In addition, since the C content is low as a cause of the crystal grains not growing uniformly, it is considered that the phase transformation during hot rolling is not sufficiently performed, the amount of austenite transformation is low, and the hot rolling structure is unstable. That is, it is considered that sufficient secondary recrystallization does not occur in the portion where the hot rolled structure is uneven, and sufficient magnetic properties are not obtained.

Based on this knowledge, the present inventors thought that secondary recrystallization can be sufficiently generated by forming an effective precipitate in order to uniformize grain growth during finish annealing. And the present inventors repeated the experiment which measures the magnetic property of the grain-oriented electromagnetic steel plate obtained by adding various elements to a slab. As a result, the present inventors found that addition of Ti and Cu was effective in order to make secondary recrystallization uniform.

This invention is made | formed based on the said knowledge, The summary is as follows.

(1) Si: 2.5 mass%-4.0 mass%, C: 0.01 mass%-0.060 mass%, Mn: 0.05 mass%-0.20 mass%, acid-soluble Al: 0.020 mass%-0.040 mass%, N: 0.002 mass% -0.012 mass%, S: 0.001 mass%-0.010 mass%, P: 0.01 mass%-0.08 mass%, and also Ti: 0.0020 mass%-0.010 mass%, and Cu: 0.010 mass%-0.50 mass% A step of obtaining at least one member selected from the group consisting of hot rolling of a steel comprising a Fe and an unavoidable impurity in a remainder, to obtain a hot rolled steel sheet;

Annealing the hot rolled steel sheet to obtain an annealed steel sheet;

A step of cold-rolling the annealed steel sheet to obtain a cold-rolled steel sheet,

Decarburizing annealing the cold rolled steel sheet at a temperature of 800 ° C to 950 ° C to obtain a decarburizing annealing steel sheet,

Next, the process of nitriding the said decarburization annealing steel plate at 700 degreeC-850 degreeC, and obtaining a nitrided steel plate,

And a step of performing annealing of the nitrided steel sheet.

(2) The method for producing a grain-oriented electromagnetic steel sheet according to (1), wherein the hot rolling of the steel is performed after heating the steel to a temperature of 1250 ° C or less.

(3) Said steel is Cr: 0.20 mass% or less, Sn: 0.20 mass% or less, Sb: 0.010 mass%-0.20 mass%, Ni: 0.010 mass%-0.20 mass%, Se: 0.005 mass%-0.02 % By mass, Bi: 0.005 mass% to 0.02 mass%, Pb: 0.005 mass% to 0.02 mass%, B: 0.005 mass% to 0.02 mass%, V: 0.005 mass% to 0.02 mass%, Mo: 0.005 mass% to 0.02 The manufacturing method of the grain-oriented electromagnetic steel sheet as described in (1) or (2) containing mass% and As: at least 1 sort (s) chosen from the group which consists of 0.005 mass%-0.02 mass%.

(4) Ti content of the said steel is 0.0020 mass%-0.0080 mass%,

Cu content of the said steel is 0.01 mass%-0.10 mass%,

When Ti content (mass%) of the said steel is represented by [Ti] and Cu content (mass%) by [Cu], the relationship of "20x [Ti] + [Cu] ≤0.18" is established, It is characterized by the above-mentioned. The manufacturing method of the grain-oriented electromagnetic steel sheet in any one of (1)-(3).

(5) The method for producing a grain-oriented electromagnetic steel sheet according to (4), wherein a relationship of "10 x [Ti] + [Cu] ≤ 0.07" is established.

According to the present invention, since an appropriate amount of Ti and / or Cu is contained in the steel, and decarburization annealing and nitriding are performed at an appropriate temperature, variations in magnetic properties can be suppressed.

FIG. 1: is a figure which shows the relationship between Ti content and Cu content, magnetic flux density, and the evaluation of the deviation.
2 is a flowchart illustrating a method of manufacturing the grain-oriented electromagnetic steel sheet according to the embodiment of the present invention.

As described above, the inventors have repeatedly conducted experiments for measuring the magnetic properties of the grain-oriented electromagnetic steel sheet obtained by adding various elements to the slab, and found that the addition of Ti and Cu is effective in order to homogenize the secondary recrystallization. .

In this experiment, the silicon steel whose C content is 0.06 mass% or less was used as the composition used for manufacture of the grain-oriented electromagnetic steel sheet by the low temperature slab heating method, for example. In addition, Ti and Cu were contained in this silicon steel in various ratios, and the steel ingot of various compositions was produced. In addition, the steel ingot was heated to a temperature of 1250 ° C. or lower to perform hot rolling, followed by cold rolling. Further, decarburization annealing was performed after cold rolling, followed by nitriding treatment and finish annealing. And the magnetic flux density B8 of the obtained grain-oriented electromagnetic steel plate was measured, and the deviation of the magnetic flux density B8 in the coil after finish annealing was investigated. The magnetic flux density B8 is a magnetic flux density generated in the grain-oriented electromagnetic steel sheet when a magnetic field of 800 A / m is applied at 50 Hz.

As a result, when the steel ingot contains 0.0020 mass%-0.010 mass% of Ti and / or 0.010 mass%-0.50 mass% of Cu, the deviation of the magnetic flux density B8 in the coil after finish annealing is remarkably reduced. Found.

An example of the result obtained by said experiment is shown in FIG. Although the detail of an experiment is mentioned later, (circle) in FIG. 1 shows that the average value of the magnetic flux density B8 of five single-plate samples is 1.90T or more, and the difference of the maximum value and minimum value of magnetic flux density B8 is 0.030T or less. 1 indicates that at least the average value of the magnetic flux density B8 of the five single-plate samples is less than 1.90T, or the difference between the maximum value and the minimum value of the magnetic flux density B8 exceeds 0.030T. In FIG. 1, when 0.0020 mass%-0.010 mass% Ti and / or 0.010 mass%-0.50 mass% Cu are contained in a steel ingot, it is clear that the mean value of magnetic flux density B8 is high and the variation of magnetic flux density B8 is small. Do.

Next, the manufacturing method of the grain-oriented electromagnetic steel sheet which concerns on embodiment of this invention is demonstrated. 2 is a flowchart illustrating a method of manufacturing the grain-oriented electromagnetic steel sheet according to the embodiment of the present invention.

In this embodiment, the slab is produced first by casting molten steel for a grain-oriented electromagnetic steel sheet of a predetermined composition (step S1). The casting method is not particularly limited. The molten steel is, for example, Si: 2.5% by mass to 4.0% by mass, C: 0.01% by mass to 0.060% by mass, Mn: 0.05% by mass to 0.20% by mass, acid-soluble Al: 0.020% by mass to 0.040% by mass, N: 0.002 It contains mass%-0.012 mass%, S: 0.001 mass%-0.010 mass%, P: 0.01 mass%-0.08 mass%. Molten steel further contains at least 1 sort (s) chosen from the group which consists of 0.0020 mass%-0.010 mass% and Cu: 0.010 mass%-0.50 mass%. That is, molten steel contains one or both of Ti and Cu so as to satisfy at least one of Ti: 0.0020 mass% or more, or Cu: 0.010 mass% or more in a range of Ti: 0.010% by mass or less and Cu: 0.50% by mass or less. do. The remainder of the molten steel consists of Fe and unavoidable impurities. In addition, inevitable impurities include an element which forms an inhibitor in the manufacturing process of the grain-oriented electromagnetic steel sheet and which remains in the grain-oriented electromagnetic steel sheet after being purified by high temperature annealing.

Here, the reasons for limiting the numerical value of the composition of the above molten steel will be described.

Si is an element which is extremely effective in increasing the electrical resistance of a grain-oriented electromagnetic steel sheet, and reducing the eddy current loss which comprises a part of iron loss. If Si content is less than 2.5 mass%, eddy current loss cannot fully be suppressed. On the other hand, when Si content exceeds 4.0 mass%, workability will fall. Therefore, Si content is made into 2.5 mass%-4.0 mass%.

C is an element effective for controlling the structure (primary recrystallization structure) obtained by the primary recrystallization. If C content is less than 0.01 mass%, this effect cannot fully be acquired. On the other hand, when the C content exceeds 0.06% by mass, the longer the time required for decarburization annealing, the discharge amount of CO ₂ is increased. In addition, when decarburization annealing is insufficient, it is difficult to obtain a grain-oriented electromagnetic steel sheet having good magnetic properties. Therefore, C content is made into 0.01 mass%-0.06 mass%. In addition, as mentioned above, since the deviation of the magnetic characteristic after finish annealing is especially remarkable when C content is 0.048 mass% or less in the prior art, this embodiment is especially effective when C content is 0.048 mass% or less. Do.

Mn reduces the iron loss by increasing the specific resistance of the grain-oriented electromagnetic steel sheet. Mn also shows the effect of preventing the occurrence of cracking in hot rolling. If the Mn content is less than 0.05% by mass, these effects cannot be sufficiently obtained. On the other hand, when Mn content exceeds 0.20 mass%, the magnetic flux density of a grain-oriented electromagnetic steel sheet will fall. Therefore, Mn content is made into 0.05 mass%-0.20 mass%.

Acid-soluble Al is an important element forming AlN which functions as an inhibitor. If the content of acid-soluble Al is less than 0.020% by mass, it is impossible to form a sufficient amount of AlN, resulting in insufficient strength of the inhibitor. On the other hand, when content of acid-soluble Al exceeds 0.040 mass%, AlN will coarsen and the inhibitor strength will fall. Therefore, content of acid-soluble Al is made into 0.020 mass%-0.040 mass%.

N is an important element that reacts with acid soluble Al to form AlN. As described later, since the nitriding treatment is performed after cold rolling, a large amount of N does not need to be contained in the steel for oriented electromagnetic steel sheets, but in order to make the N content less than 0.002% by mass, a large load is required during steelmaking. There is a case. On the other hand, when N content exceeds 0.012 mass%, the void called blister will generate | occur | produce in a steel plate at the time of cold rolling. Therefore, N content is made into 0.002 mass%-0.012 mass%. In order to further reduce the blister, the N content is preferably 0.010% by mass or less.

S is an important element that reacts with Mn to form MnS precipitates. MnS precipitates mainly affect primary recrystallization and exhibit an effect of suppressing local fluctuations in primary recrystallization grain growth caused by hot rolling. If the Mn content is less than 0.001 mass%, this effect cannot be sufficiently obtained. On the other hand, when Mn content exceeds 0.010 mass%, magnetic property will fall easily. Therefore, Mn content is made into 0.001 mass%-0.010 mass%. In order to further improve magnetic properties, the Mn content is preferably 0.009% by mass or less.

P reduces iron loss by increasing the specific resistance of the grain-oriented electromagnetic steel sheet. If P content is less than 0.01 mass%, this effect cannot fully be acquired. On the other hand, when P content exceeds 0.08 mass%, cold rolling may become difficult. Therefore, P content is made into 0.01 mass%-0.08 mass%.

Ti reacts with N to form TiN precipitates. In addition, Cu reacts with S to form CuS precipitates. And these precipitates have the effect of homogenizing the growth of crystal grains in finish annealing irrespective of the site of the coil, and suppressing the variation of the magnetic properties of the grain-oriented electromagnetic steel sheet. In particular, it is thought that the TiN precipitate suppresses the variation in grain growth in the high temperature region of the finish annealing and reduces the variation in the magnetic properties of the grain-oriented electromagnetic steel sheet. Moreover, it is thought that CuS precipitate suppresses the dispersion | variation in the grain growth in the low temperature area | region of decarburization annealing or finish annealing, and makes small the dispersion | variation in the magnetic characteristic of a grain-oriented electromagnetic steel sheet. If Ti content is less than 0.0020 mass% and Cu content is less than 0.010 mass%, these effects cannot fully be acquired. On the other hand, when Ti content exceeds 0.010 mass%, TiN precipitate will form excessively and will remain even after finish annealing. Similarly, when Cu content exceeds 0.50 mass%, CuS precipitate will form excessively and will remain even after finish annealing. And if these precipitates remain | survive on a grain-oriented electromagnetic steel sheet, it will become difficult to acquire a high magnetic characteristic. Therefore, molten steel contains one or both of Ti and Cu so as to satisfy at least one of Ti: 0.0020 mass% or more or Cu: 0.010 mass% or more in the range of Ti: 0.010 mass% or less and Cu: 0.50 mass% or less. do. That is, molten steel contains at least 1 sort (s) chosen from the group which consists of 0.0020 mass%-0.010 mass% and Cu: 0.010 mass%-0.50 mass%.

Moreover, it is preferable that the minimum of Ti content is 0.0020 mass%, and it is preferable that the upper limit of Ti content is 0.0080 mass%. Moreover, it is preferable that the minimum of Cu content is 0.01 mass%, and it is preferable that the upper limit of Cu content is 0.10 mass%. Moreover, when Ti content (mass%) is represented by [Ti] and Cu content (mass%) by [Cu], it is preferable that the relationship of "20x [Ti] + [Cu] ≤0.18" is established, It is more preferable that the relationship of "10x [Ti] + [Cu] ≤0.07" is established.

Moreover, at least 1 sort (s) of the following various elements may be contained in molten steel.

Cr and Sn make the property of the oxide layer formed at the time of decarburization annealing favorable, and the property of the glass film formed using this oxide layer at the time of finish annealing is also good. In other words, Cr and Sn improve the magnetic properties through the stabilization of the formation of the oxide layer and the glass film, and suppress the variation in the magnetic properties. However, when Cr content exceeds 0.20 mass%, formation of a glass film may become unstable. Moreover, when Sn content exceeds 0.20 mass%, the surface of a steel plate will become difficult to oxidize, and formation of a glass film may become inadequate. Therefore, it is preferable that both Cr content and Sn content are 0.20 mass% or less. In addition, in order to fully acquire the said effect, it is preferable that both Cr content and Sn content are 0.01 mass% or more. In addition, Sn is a grain boundary segregation element and has the effect of stabilizing secondary recrystallization.

Moreover, Sb: 0.010 mass%-0.20 mass%, Ni: 0.010 mass%-0.20 mass%, Se: 0.005 mass%-0.02 mass%, Bi: 0.005 mass%-0.02 mass%, Pb: 0.005 mass%-0.02 mass %, B: 0.005 mass%-0.02 mass%, V: 0.005 mass%-0.02 mass%, Mo: 0.005 mass%-0.02 mass%, and / or As: 0.005 mass%-0.02 mass% may be contained in molten steel. . These elements are all inhibitor strengthening elements.

In this embodiment, after the slab is produced from molten steel having such a composition, the slab is heated (step S2). The heating temperature is preferably 1250 DEG C or lower from the viewpoint of energy saving.

Subsequently, the slab is hot-rolled to obtain a hot-rolled steel sheet (step S3). The thickness of the hot rolled steel sheet is not particularly limited and is, for example, 1.8 mm to 3.5 mm.

Thereafter, the annealing of the hot rolled steel sheet is performed to obtain an annealed steel sheet (step S4). The conditions of annealing are not specifically limited, For example, it carries out for 30 second-10 minutes at the temperature of 750 degreeC-1200 degreeC. This annealing improves the magnetic properties.

Next, a cold rolled steel sheet is obtained by performing cold rolling of an annealing steel sheet (step S5). Cold rolling may be performed only once, or cold rolling may be performed a plurality of times while intermediate annealing is performed. It is preferable to perform an intermediate annealing for 30 second-10 minutes at the temperature of 750 degreeC-1200 degreeC, for example.

In addition, when cold rolling is performed without performing the above intermediate annealing, it may be difficult to obtain uniform characteristics. Further, when cold rolling is performed a plurality of times while performing intermediate annealing, it is easy to obtain uniform characteristics, but the magnetic flux density may be lowered. Therefore, it is preferable to determine the frequency | count of cold rolling and the presence or absence of intermediate annealing according to the characteristic and cost calculated | required by the finally obtained grain-oriented electromagnetic steel plate.

In any case, the reduction ratio of the final cold rolling is preferably 80% to 95%.

After cold rolling, a decarburizing annealing steel sheet is obtained by performing decarburization annealing on the cold rolled steel sheet in the wet atmosphere containing hydrogen and nitrogen of 800 degreeC-950 degreeC (step S6). The carbon in the steel sheet is removed by decarburization annealing, and primary recrystallization occurs. If the temperature of decarburization annealing is less than 800 degreeC, the crystal grain (primary recrystallized grain) obtained by primary recrystallization is too small, and a subsequent secondary recrystallization is not fully expressed. On the other hand, when the temperature of decarburization annealing exceeds 950 degreeC, a primary recrystallization grain is too large and subsequent secondary recrystallization does not fully express.

Next, a nitriding-treated steel sheet is obtained by performing a nitriding treatment on a decarburized annealing steel sheet in an atmosphere containing a gas having a nitriding ability such as hydrogen, nitrogen, and ammonia at 700 ° C to 850 ° C (step S7). Nitriding increases the nitrogen content in the steel sheet. If the temperature of the nitriding treatment is less than 700 ° C or exceeds 850 ° C, nitrogen is less likely to diffuse to the inside of the steel sheet, and subsequent secondary recrystallization is not sufficiently expressed.

Then, the annealing separator which has MgO as a main component is apply | coated to the surface of a nitrided steel sheet with a water slurry, and the nitrided steel sheet is wound up in coil shape. And a coil finish annealed steel plate is obtained by performing batch type annealing on a coiled nitride steel sheet (step S8). By the finishing annealing, secondary recrystallization occurs.

Thereafter, the coil-shaped finish annealing steel sheet is wound and the annealing separator is removed. Subsequently, a coating liquid containing aluminum phosphate and colloidal silica as a main component is applied to the surface of the finish-annealed steel sheet, and this baking is performed to form an insulating film (step S9).

In this way, a grain-oriented electromagnetic steel sheet can be manufactured.

In addition, the steel made into the object of hot rolling is not limited to the slab obtained by casting of molten steel, You may use what is called a thin slab. In addition, when using a thin slab, it is not necessary to necessarily perform slab heating of 1250 degrees C or less.

Example

Next, experiments conducted by the present inventors will be described. The conditions and the like in these experiments are employed to confirm the feasibility and effect of the present invention, and the present invention is not limited to these examples.

(First experiment)

First, Si: 3.2 mass%, C: 0.055 mass%, Mn: 0.10 mass%, acid soluble Al: 0.028 mass%, N: 0.003 mass%, S: 0.0060 mass% and P: 0.030 mass% , 15 kinds of steel ingots containing Ti and Cu in the amounts shown in Table 1, the remainder being made of Fe and unavoidable impurities were produced using a vacuum melting furnace. Subsequently, annealing of the steel ingot was performed at 1150 ° C for 1 hour, and then hot rolling was performed to obtain a hot rolled steel sheet having a thickness of 2.3 mm.

Subsequently, annealing of the hot rolled steel sheet was performed at 1100 ° C. for 120 seconds to obtain an annealed steel sheet. Subsequently, pickling of the annealed steel sheet was performed, followed by cold rolling of the annealed steel sheet to obtain a cold rolled steel sheet having a thickness of 0.23 mm. Subsequently, decarburization annealing was performed for 100 seconds at 860 ° C. in a gas atmosphere containing water vapor, hydrogen and nitrogen to obtain a decarburization annealing steel sheet. Subsequently, nitriding treatment of the decarburization annealing steel sheet was carried out for 20 seconds in a gas atmosphere containing hydrogen, nitrogen and ammonia at 770 ° C to obtain a nitriding steel sheet.

Thereafter, an annealing separator containing MgO as a main component was applied to the surface of the nitrided steel sheet with a water slurry. And finish annealing was performed at 1200 degreeC for 20 hours, and the finish annealing steel plate was obtained. Subsequently, the finish-annealed steel sheet was washed with water, and then sheared to a size for single plate magnetic measurement having a width of 60 mm and a length of 300 mm. Subsequently, a coating liquid containing aluminum phosphate and colloidal silica as a main component was applied to the surface of the finished annealing steel sheet, and this baking was performed to form an insulating film. In this way, a sample of the grain-oriented electromagnetic steel sheet was obtained.

And the magnetic flux density B8 of each grain-oriented electromagnetic steel plate was measured. As described above, the magnetic flux density B8 is the magnetic flux density generated in the grain-oriented electromagnetic steel sheet when a magnetic field of 800 A / m is applied at 50 Hz. In addition, for each sample, the magnetic flux density B8 of the five measurement single plate samples was measured. And the average value "average B8", the highest value "B8 max", and the minimum value "B8 min" were calculated | required for every sample. Moreover, the difference "(DELTA) B8" of the highest value "B8 max" and the minimum value "B8 min" was also calculated | required. The difference "ΔB8" is an index indicating the fluctuation range of the magnetic characteristics. These results are shown in Table 1 with Ti content and Cu content. Moreover, the evaluation result based on the average value "average B8" and the difference "(DELTA) B8" is shown in FIG. As described above, the O symbol in FIG. 1 indicates that the average value "average B8" is 1.90T or more, and the difference "ΔB8" is 0.030T or less. 1 indicates that the average value "average B8" is less than 1.90T or the difference "ΔB8" exceeds 0.030T.

As shown in Table 1 and FIG. 1, in samples Nos. 11 to 15 in which the Ti content and the Cu content are within the present invention, the average value "average B8" is larger than 1.90T and the difference "ΔB8" is 0.030T. It was small as follows. That is, high magnetic characteristics were obtained, and the variation of the magnetic characteristics was small.

In particular, when Ti content (mass%) is represented by [Ti] and Cu content (mass%) by [Cu], Sample No. 11 in which the relationship of "20 x [Ti] + [Cu] ≤ 0.18" is established In Nos. 13 and 15, the balance between the average value "average B8" and the difference "ΔB8" was good. Especially, in sample No. 15 in which the relationship of “10 × [Ti] + [Cu] ≦ 0.07” was established, the balance between the average value “average B8” and the difference “ΔB8” was extremely good.

On the other hand, the difference "(DELTA) B8" was larger than 0.030T in sample No. 1 whose Ti content is less than 0.0020 mass% and Cu content is less than 0.010 mass%. That is, the variation of magnetic characteristics was large. In addition, in sample No. 5 in which Ti content exceeds 0.010 mass%, and sample No. 10 in which Cu content exceeds 0.50 mass%, a large amount of precipitates were contained and it affected the finish annealing, and the average value "average B8 Was smaller than 1.90T. In other words, it was not possible to obtain sufficiently high magnetic properties.

(Second Experiment)

First, Si: 3.2 mass%, C: 0.051 mass%, Mn: 0.09 mass%, acid soluble Al: 0.026 mass%, N: 0.004 mass%, S: 0.0053 mass%, P: 0.027 mass%, Ti: 0.0024 mass % And Cu: 0.029 mass%, and the remainder was made of a steel ingot made of Fe and unavoidable impurities using a vacuum melting furnace. Subsequently, annealing of the steel ingot was performed at 1150 ° C for 1 hour, and then hot rolling was performed to obtain a hot rolled steel sheet having a thickness of 2.4 mm.

Next, annealing of the hot rolled steel sheet at 1090 ° C. was performed for 120 seconds to obtain an annealed steel sheet. Subsequently, pickling of the annealed steel sheet was performed, followed by cold rolling of the annealed steel sheet to obtain a cold rolled steel sheet having a thickness of 0.23 mm. Subsequently, eight sheets of annealing steel sheets are cut out from the cold rolled steel sheet, and decarburization annealing of the steel sheet is performed for 80 seconds in a gas atmosphere containing water vapor, hydrogen, and nitrogen at a temperature T1 of 790 ° C to 960 ° C shown in Table 2. Got. Subsequently, nitriding treatment of the decarburization annealing steel sheet was performed for 20 seconds in a gas atmosphere containing water vapor, hydrogen, nitrogen and ammonia at a temperature T2 of 680 ° C to 880 ° C shown in Table 2.

Thereafter, an annealing separator containing MgO as a main component was applied to the surface of the nitrided steel sheet with a water slurry. And finish annealing was performed at 1200 degreeC for 20 hours, and the finish annealing steel plate was obtained. Subsequently, it carried out similarly to 1st experiment, the process from water washing to formation of an insulating film was performed, and the sample of the grain-oriented electromagnetic steel plate was obtained.

Then, in the same manner as in the first experiment, the average value "average B8", the maximum value "B8 max", the minimum value "B8 min", and the difference "ΔB8" were calculated for each sample. These results are shown in Table 2 together with temperature T1 and temperature T2.

As shown in Table 2, in samples Nos. 22 to 24 and No. 27 in which the temperature T1 of the decarburization annealing and the temperature T2 of the nitriding treatment are within the scope of the present invention, the average value "average B8" is larger than 1.90T, The difference "ΔB8" was small at 0.030T or less. That is, high magnetic characteristics were obtained, and the variation of the magnetic characteristics was small.

On the other hand, in sample No. 21 whose temperature T1 of decarburization annealing was less than 800 degreeC, average value "average B8" was small to less than 1.90T. In sample No. 25 whose temperature T1 of decarburization annealing was more than 950 degreeC, difference "(DELTA) B8" was larger than 0.030T and average value "average B8" was small to less than 1.90T. Moreover, in sample No. 26 with the temperature T2 of nitriding process less than 700 degreeC, average value "average B8" was small to less than 1.90T. The sample No. whose temperature T2 of nitriding treatment is more than 850 degreeC. In 28, difference "(DELTA) B8" was larger than 0.030T and average value "average B8" was smaller than 1.90T.

(Third experiment)

First, Si: 3.2 mass%, Mn: 0.09 mass%, acid-soluble Al: 0.026 mass%, N: 0.004 mass%, S: 0.0053 mass%, P: 0.027 mass%, and also the quantity shown in Table 3 20 kinds of steel ingots containing C, Ti, and Cu, the remainder being made of Fe and unavoidable impurities, were produced using a vacuum melting furnace. Subsequently, annealing of the steel ingot was performed at 1150 ° C for 1 hour, and then hot rolling was performed to obtain a hot rolled steel sheet having a thickness of 2.4 mm.

Next, annealing of the hot rolled steel sheet at 1090 ° C. was performed for 120 seconds to obtain an annealed steel sheet. Subsequently, pickling of the annealed steel sheet was performed, followed by cold rolling of the annealed steel sheet to obtain a cold rolled steel sheet having a thickness of 0.23 mm. Next, the annealing steel sheet was cut out from the cold rolled steel sheet, and decarburization annealing of the steel sheet was performed at 860 ° C. in a gas atmosphere containing steam, hydrogen, and nitrogen for 80 seconds to obtain a decarburization annealing steel sheet. Subsequently, nitriding treatment of the decarburization annealing steel sheet was performed for 20 seconds in a gas atmosphere containing water vapor, hydrogen, nitrogen and ammonia at 760 ° C to obtain a nitriding steel sheet.

Thereafter, an annealing separator containing MgO as a main component was applied to the surface of the nitrided steel sheet with a water slurry. And finish annealing was performed at 1200 degreeC for 20 hours, and the finish annealing steel plate was obtained. Subsequently, it carried out similarly to 1st experiment, the process from water washing to formation of an insulating film was performed, and the sample of the grain-oriented electromagnetic steel plate was obtained.

Then, in the same manner as in the first experiment, the average value "average B8", the maximum value "B8 max", the minimum value "B8 min", and the difference "ΔB8" were calculated for each sample. These results are shown in Table 3 with C content, Ti content, and Cu content.

As shown in Table 3, samples No. 32 to No. 34, No. 37 to No. 39, No. 42 to No. 44, and No. 47 to No. C, Ti content and Cu content are within the scope of the present invention. In No. 49, the average value "average B8" was large in 1.90T or more, and the difference "(DELTA) B8" was small in 0.025T or less. That is, high magnetic characteristics were obtained, and the variation of the magnetic characteristics was small. In particular, when the C content was small, good results were obtained.

Further, Sample Nos. 32 and No. 2 in which the Ti content was 0.0020% by mass to 0.080% by mass and the Cu content was 0.010% by mass to 0.10% by mass, and a relationship of "20 x [Ti] + [Cu] ≤ 0.18" were established. In 33, No. 37, No. 38, No. 42, No. 43, No. 47 and No. 48, the balance between the average value "average B8" and the difference "ΔB8" was good. Especially, in sample Nos. 32, No. 37, No. 42 and No. 47, in which the relationship of "10 x [Ti] + [Cu] ≤ 0.07" was established, the average value "average B8" and the difference "ΔB8" The balance of was extremely good.

On the other hand, in Sample Nos. 31, No. 36, No. 41, and No. 46, where the Ti content was less than 0.0020% by mass and the Cu content was less than 0.010% by mass, the difference "ΔB8" was greater than 0.030T. Especially, in sample No.31 and No.36 with low C content, the average value "average B8" was small less than 1.90T. In addition, in sample No. 35, No. 40, No. 45, and No. 50 in which Ti content exceeds 0.010 mass% and Cu content exceeds 0.50 mass%, the average value "average B8" was small below 1.90T. All.

(Fourth experiment)

First, Si: 3.2 mass%, C: 0.048 mass%, Mn: 0.08 mass%, acid soluble Al: 0.028 mass%, N: 0.004 mass%, S: 0.0061 mass%, P: 0.033 mass%, Ti: 0.0024 mass 10 types of steel ingots containing% and Cu: 0.029 mass%, containing Cr and Sn in the amounts shown in Table 4, and the remaining portions of Fe and unavoidable impurities were produced using a vacuum melting furnace. Subsequently, annealing of the steel ingot was performed at 1100 ° C. for 1 hour, and then hot rolling was performed to obtain a hot rolled steel sheet having a thickness of 2.3 mm.

Subsequently, annealing of the hot rolled steel sheet at 1080 ° C. was performed for 120 seconds to obtain an annealed steel sheet. Subsequently, pickling of the annealed steel sheet was performed, followed by cold rolling of the annealed steel sheet to obtain a cold rolled steel sheet having a thickness of 0.23 mm. Subsequently, decarburization annealing was performed for 90 seconds at 870 ° C. in a gas atmosphere containing water vapor, hydrogen, and nitrogen to obtain a decarburization annealing steel sheet. Subsequently, nitriding treatment of the decarburization annealing steel sheet was performed for 20 seconds in a gas atmosphere containing hydrogen, nitrogen and ammonia at 760 ° C to obtain a nitriding steel sheet.

Thereafter, an annealing separator containing MgO as a main component was applied to the surface of the nitrided steel sheet with a water slurry. And finish annealing was performed at 1200 degreeC for 20 hours, and the finish annealing steel plate was obtained. Subsequently, it carried out similarly to 1st experiment, the process from water washing to formation of an insulating film was performed, and the sample of the grain-oriented electromagnetic steel plate was obtained.

And similarly to the 1st experiment, the average value "average B8", the highest value "B8 max", the minimum value "B8 min", and the difference "(DELTA) B8" were calculated | required for every sample. These results are shown in Table 4 with Cr content and Sn content.

As shown in Table 4, in any of samples Nos. 51 to 53, 55, 56, and 58 to 60, the average value "average B8" was larger than 1.90T and the difference "ΔB8" was small to 0.030T or less. That is, high magnetic characteristics were obtained, and the variation of the magnetic characteristics was small. Especially, Sample No. 52, No. 53, No. 55, No. 56, No. 58-No containing 0.010 mass%-0.20 mass% Cr and / or 0.010 mass%-0.20 mass% Sn At .60, the average value "average B8" was especially large at 1.91T or more, and the difference "ΔB8" was especially small at 0.025T or less.

Industrial Applicability

The present invention can be used, for example, in the electromagnetic steel sheet manufacturing industry and the electromagnetic steel sheet utilization industry.

Claims (16)

Si: 2.5 mass%-4.0 mass%, C: 0.01 mass%-0.060 mass%, Mn: 0.05 mass%-0.20 mass%, acid-soluble Al: 0.020 mass%-0.040 mass%, N: 0.002 mass%-0.012 mass %, S: 0.001% by mass to 0.010% by mass and P: 0.01% by mass to 0.08% by mass, and also contain Ti: 0.0028% by mass to 0.010% by mass and Cu: 0.010% by mass to 0.033% by mass, The remaining portion is subjected to hot rolling of steel made of Fe and unavoidable impurities to obtain a hot rolled steel sheet;
Annealing the hot rolled steel sheet to obtain an annealed steel sheet;
A step of cold-rolling the annealed steel sheet to obtain a cold-rolled steel sheet,
Decarburizing annealing the cold rolled steel sheet at a temperature of 800 ° C to 950 ° C to obtain a decarburizing annealing steel sheet,
Next, the process of nitriding the said decarburization annealing steel plate at 700 degreeC-850 degreeC, and obtaining a nitrided steel plate,
Applying an annealing separator containing MgO to the surface of the nitrided steel sheet with a water slurry, winding the nitrided steel sheet into a coil shape, and performing batch finish annealing,
When Ti content (mass%) of the said steel is represented by [Ti] and Cu content (mass%) as [Cu], the relationship of "20x [Ti] + [Cu] ≤0.18" is established, It is characterized by the above-mentioned. , Manufacturing method of grain oriented electromagnetic steel sheet. The method for producing a grain-oriented electromagnetic steel sheet according to claim 1, wherein the hot rolling of the steel is performed after heating the steel to a temperature of 1250 ° C or less. The said steel is further Cr: 0.010 mass%-0.20 mass%, Sn: 0.010 mass%-0.20 mass%, Sb: 0.010 mass%-0.20 mass%, Ni: 0.010 mass %-0.20 mass%, Se: 0.005 mass%-0.02 mass%, Bi: 0.005 mass%-0.02 mass%, Pb: 0.005 mass%-0.02 mass%, B: 0.005 mass%-0.02 mass%, V: 0.005 mass At least 1 sort (s) chosen from the group which consists of%-0.02 mass%, Mo: 0.005 mass%-0.02 mass%, As: 0.005 mass%-0.02 mass% is contained, The manufacturing method of the grain-oriented electromagnetic steel sheet characterized by the above-mentioned. The said steel is further Cr: 0.20 mass% or less, Sn: 0.20 mass% or less, Sb: 0.010 mass%-0.20 mass%, Ni: 0.010 mass%-0.20 mass%, Se: 0.005 mass%-0.02 mass%, Bi: 0.005 mass%-0.02 mass%, Pb: 0.005 mass%-0.02 mass%, B: 0.005 mass%-0.02 mass%, V: 0.005 mass%-0.02 mass%, At least 1 sort (s) chosen from the group which consists of Mo: 0.005 mass%-0.02 mass%, and As: 0.005 mass%-0.02 mass% is contained, The manufacturing method of the grain-oriented electromagnetic steel sheet characterized by the above-mentioned. The said steel further contains at least 1 sort (s) chosen from the group which consists of 0.010 mass%-0.20 mass% Cr, and 0.010 mass%-0.20 mass% Sn, The said steel is characterized by the above-mentioned. , Manufacturing method of grain oriented electromagnetic steel sheet. The said steel further contains at least 1 sort (s) chosen from the group which consists of Cr: 0.20 mass% or less and Sn: 0.20 mass% or less, The manufacture of the grain-oriented electromagnetic steel sheet of Claim 1 or 2 characterized by the above-mentioned. Way. The Ti content of the said steel is 0.0028 mass%-0.0080 mass%, The manufacturing method of the grain-oriented electromagnetic steel sheet of Claim 1 or 2 characterized by the above-mentioned. The Ti content of the said steel is 0.0028 mass%-0.0080 mass%, The manufacturing method of the grain-oriented electromagnetic steel sheet of Claim 3 characterized by the above-mentioned. The method for producing a grain-oriented electromagnetic steel sheet according to claim 4, wherein the Ti content of the steel is 0.0028% by mass to 0.0080% by mass. The Ti content of the said steel is 0.0028 mass%-0.0080 mass%, The manufacturing method of the grain-oriented electromagnetic steel sheet of Claim 5 characterized by the above-mentioned. The Ti content of the said steel is 0.0028 mass%-0.0080 mass%, The manufacturing method of the grain-oriented electromagnetic steel sheet of Claim 6 characterized by the above-mentioned. The method of manufacturing a grain-oriented electromagnetic steel sheet according to claim 1 or 2, wherein a relationship of "10 x [Ti] + [Cu] ≤ 0.07" is established. The method of manufacturing a grain-oriented electromagnetic steel sheet according to claim 3, wherein a relationship of "10 x [Ti] + [Cu] ≤ 0.07" is established. The method of manufacturing a grain-oriented electromagnetic steel sheet according to claim 4, wherein a relationship of "10 x [Ti] + [Cu] ≤ 0.07" is established. The method of manufacturing a grain-oriented electromagnetic steel sheet according to claim 5, wherein a relationship of "10 x [Ti] + [Cu] ≤ 0.07" is established. The method of manufacturing a grain-oriented electromagnetic steel sheet according to claim 6, wherein a relationship of "10 x [Ti] + [Cu] ≤ 0.07" is established.

Images