KR20130014892A - Grain-oriented electrical steel sheets having excellent magnetic properties and method for manufacturing the same - Google Patents

Abstract

PURPOSE: A grain oriented electrical steel sheet with an excellent magnetic property and a manufacturing method thereof are provided to improve crystal grain growth preventing power between the secondary recrystalization and cause the secondary recrystalization steadily, thereby improve the magnetic property greatly by an eddy flow loss diminishing effect by the thick reduction. CONSTITUTION: A grain oriented electrical steel sheet with an excellent magnetic property comprises at least one factor of the selected from the group comprised of Si: 2.0~4.0%, C: less than 0.085%, the acid solubility Al: 0.015~0.04%, Mn: less than 0.20%, N: less than 0.010%, S: less than 0.010%, Sn, Sb, and P in a % weight, and the remaining Fe and the impurity mixed inevitably. A grain oriented electrical steel sheet with an excellent magnetic property with a β angle 1.5~2.6°, δ angle 5°, and the plate thickness 0.10~0.50mm in the absolute value area weighted average of the crystal orientation has the excellent magnetic property. A Β angle means the average angle of misorientation from the direction over {110}<001> in the rolling right angle direction surrounding of the secondary recrystallization collection, and a δ angle means the average angle of misorientation from <001>crystal orientation and the rolling direction of the secondary recrystallization collection.

Description

Oriented electrical steel with excellent magnetism and its manufacturing method {GRAIN-ORIENTED ELECTRICAL STEEL SHEETS HAVING EXCELLENT MAGNETIC PROPERTIES AND METHOD FOR MANUFACTURING THE SAME}

The present invention relates to a technique for manufacturing a grain-oriented electrical steel sheet, and more specifically, the temperature raising pattern of recrystallization annealing is made into three stages of super-fast temperature rising, rapid temperature rising and general temperature rising, and by containing an appropriate amount of alloy components segregating at grain boundaries, It relates to a method for producing a grain-oriented electrical steel sheet to significantly improve.

The directional electrical steel sheet is composed of crystal grains having a so-called Goss orientation in which the crystal orientation of the steel sheet face is {110} plane and the crystal orientation in the rolling direction is parallel to the <001> axis, It is a soft magnetic material.

A grain-oriented electrical steel sheet is manufactured by combining several manufacturing processes to obtain a {110} <001> texture. Generally, steel slab heating, hot rolling, hot rolled sheet annealing, cold rolling, recrystallization annealing, and final annealing are performed. Are manufactured.

This oriented electrical steel sheet is a secondary material obtained by inhibiting the growth of primary recrystallized grains in the final annealing process after the primary recrystallization in recrystallization annealing and selectively growing grains of {110} <001> orientation among the grains in which growth is suppressed. Since it is intended to exhibit excellent magnetic properties by the recrystallized structure, the growth inhibitory agent (hereinafter referred to as 'inhibitor') of the primary recrystallized grain is very important.

Primary recrystallization is a term used to refer to recrystallization, which is commonly referred to as a new crystal grain nucleated and grain growth occurs without the strain is modified above a certain temperature.

The core of the grain-oriented electrical steel sheet manufacturing technology is to preferentially grow grains having a structure of {110} <001> orientation stably in the final annealing process among the grains whose growth is suppressed.

In the final annealing process, the secondary recrystallization starts to occur because the inhibitors grow or decompose as the temperature increases and the function of inhibiting the growth of the primary recrystallized grains is lost. Particle growth occurs in a relatively short time.

In the final annealing process, the growth of all primary recrystallization grains should be suppressed until just before secondary recrystallization occurs. For this purpose, the precipitates should be uniformly distributed in a sufficient amount and in an appropriate size, and thermally stable up to the high temperature just before secondary recrystallization occurs. Should not be easily disassembled.

Primary recrystallization is usually performed with decarbonization annealing performed after cold rolling or immediately after decarbonization annealing is performed, and uniform and appropriate grain sizes are formed by primary recrystallization.

In general, the orientation of the recrystallized grains in a grain-oriented electrical steel sheet has a collective structure in which the orientations of the grains are dispersed in various directions and the orientations other than the go-bearing orientation are arranged in parallel with the surface orientation. low.

Conventional techniques for improving the magnetic properties by controlling the temperature raising conditions during recrystallization annealing are disclosed in Japanese Patent Publication Nos. 2003-3213, 2008-1978, 2008-1979, 2008-1980, 2008-1981, 2008-1982 and 2008-1983. In the process of raising the temperature, techniques that have introduced rapid temperature increase have been reported.

Japanese Patent Laid-Open Publication No. 2003-3213 proposed a technique for producing mirror-oriented electrical steel sheets with high magnetic flux density by controlling I [111] / I [411] to 2.5 or less in the amount of nitriding and after annealing. It is disclosed to control the heating rate of the aluminum and nitrogen amount and the temperature increase process of the decarbonization annealing process to control the temperature.

Japanese Patent Laid-Open Publication No. 2008-1978, 2008-1979, 2008-1980, 2008-1981, 2008-1982, 2008-1983 are decarburized during hot-rolled sheet annealing or at the same time controlling the lamellar spacing through controlling the hot-rolled sheet annealing temperature It proposes a method of improving the magnetic flux density by rapid heating at a heating rate of 40 ℃ / sec, preferably 75 ~ 125 ℃ / second in the temperature range of 550 ~ 720 ℃.

Such prior art reports that the grains of the {411} orientation in the primary recrystallization affect the preferential growth of the secondary recrystallization grains in the {110} orientation, and the {111} of the primary recrystallization aggregate after decarbonization. It is disclosed to produce a grain-oriented electrical steel sheet having a high magnetic flux density by adjusting the / {411} ratio to 3.0 or less, followed by nitriding and strengthening the inhibitor.

However, the above-described conventional technique does not directly increase the ratio of grains having a goth orientation, but indirectly affects abnormal grain growth (secondary recrystallization) of goth orientation during secondary recrystallization annealing after decarbonization annealing. It is just a technique to increase the ratio of grains having an orientation, and it does not effectively increase the fraction of goth bearing.

JP 2003-3213 A (2003.1.08.) JP 2008-1978 A (2008.1.10.) JP 2008-1979 A (2008.1.10.) JP 2008-1980 A (2008.1.10.) JP 2008-1981 A (2008.1.10.) JP 2008-1982 A (2008.1.10.) JP 2008-1983 A (2008.1.10.)

The present invention has been made to solve the above-mentioned problems of the prior art, the precision goss orientation crystal grains on the first recrystallized steel sheet by the three steps of the initial temperature rise, rapid temperature rise and general temperature rise of the recrystallization annealing Directionality to increase the volume fraction of, increase the crystal orientation density after secondary recrystallization by strengthening the secondary recrystallization by strengthening the secondary recrystallization by containing an appropriate amount of alloy components segregated at the grain boundaries It is an object to provide a new manufacturing technology of electrical steel sheet.

Method for producing a grain-oriented electrical steel sheet of the present invention for solving the above problems by weight, Si: 2.0 ~ 4.0%, C: 0.085% or less, acid-soluble Al: 0.015 ~ 0.04%, Mn: 0.20% or less, N: 0.010 % Or less, S: 0.010% or less and at least one or more selected from the group consisting of Sn, Sb, and P: 0.01 to 0.15%, and hot-rolled steel slabs made of remainder Fe and other unavoidable impurities Next, cold rolled to a thickness of 0.10 ~ 0.50mm, recrystallized annealing the cold rolled steel sheet and finally annealing to produce a grain-oriented electrical steel sheet,

The recrystallization annealing is a rapid heating step of increasing the temperature at an average temperature increase rate of more than 300 ℃ / sec, and a rapid temperature rising rate of lower than the average temperature increase rate of the initial speed increase process after the rapid heating step at a higher temperature increase rate than 100 ℃ / sec The process, and after the rapid temperature increase process is characterized in that it includes a general temperature increase process for increasing the temperature at an average temperature increase rate lower than the average temperature increase rate in the rapid temperature increase process.

In the method of manufacturing a grain-oriented electrical steel sheet of the present invention, the rapid heating process may be performed at an average temperature increase rate of 300 ° C./sec or more, more preferably 400 ° C./sec or more in a section ranging from room temperature to 500 ° C. to 600 ° C., and the rapid temperature rising. The process is rapidly heated at an average temperature increase rate of 100 to 250 ° C / sec, more preferably 120 to 180 ° C / sec in a section from 500 to 600 ° C temperature to 700 ° C, the general temperature rising process is decarbonized from 700 ° C It is characterized in that the temperature increase at an average temperature increase rate of 40 ℃ / sec or less in the section leading to the temperature.

The grain-oriented electrical steel sheet having excellent magnetic properties of the present invention is manufactured by the above-described method for producing a grain-oriented electrical steel sheet in weight%, Si: 2.0 to 4.0%, C: 0.085% or less, acid soluble Al: 0.015 to 0.04%, Mn: 0.20 % Or less, N: 0.010% or less, S: 0.010% or less and at least one or more selected from the group consisting of Sn, Sb, and P: 0.01 to 0.15%, and remain with Fe and other unavoidable impurities. It is characterized by the area-weighted average of the absolute values of the crystal orientations, β angle of 1.5 to 2.6 °, δ angle of 5 ° or less, and plate thickness of 0.10 to 0.50 mm.

According to the present invention, by increasing the volume fraction of the fine Goths azimuth grains on the first recrystallized steel sheet by introducing three steps of temperature rising patterns (fast heating, rapid heating and general heating) in the temperature raising process of recrystallization annealing The crystal orientation density after recrystallization can be improved. In addition, when grains of segregation elements Sn, Sb, and P are added in an appropriate amount to improve grain growth inhibition before secondary recrystallization, when ultrathin products having a thickness of 0.10 to 0.18 mm are produced, the secondary recrystallization is stably reduced, thereby reducing the eddy current loss due to the thickness reduction. It can greatly improve the magnetic properties, and in the case of manufacturing a thick product of 0.35 ~ 0.50mm thickness can improve the productivity and the magnetic properties and noise characteristics at the time of transformer manufacturing.

Hereinafter, the manufacturing method of the grain-oriented electrical steel sheet of this invention is demonstrated in detail.

The present inventors have studied the nucleation of primary recrystallization of oriented electrical steel, in particular, the behavior in the primary recrystallization of the Goss orientation ({110} <001>) that can grow to nuclei during secondary recrystallization. The nucleation of the goth bearing occurs within the shear band where the strain energy is concentrated during the first recrystallization after the strong deformation, and the accumulated strain energy of the shear strain is partially recovered during the temperature rise during recrystallization annealing. It can be inferred that this would result in a decrease in energy, thereby reducing the goth's nucleation site.

In light of this, the inventors have conducted studies and experiments on the temperature raising conditions during recrystallization annealing so that the accumulated strain energy of the shear deformation zone can be reduced by recovery until the recrystallization period, thereby increasing the nucleation of the Goth bearing. As a result, in the recrystallization annealing process, a three-step temperature rising pattern consisting of two stages of rapid temperature rise (super rapid and rapid temperature rise) and a general temperature rise is introduced. For the first time, the introduction of an ultra-rapid temperature ramping process at high speeds can significantly improve the fraction of Goth bearings, especially the Exact Goss bearing.

The present invention is in weight%, Si: 2.0 ~ 4.0%, C: 0.085% or less, acid soluble Al: 0.015 ~ 0.04%, Mn: 0.20% or less, N: 0.010% or less, S: 0.010% or less and Sn, Sb At least one member selected from the group consisting of P: 0.01 to 0.15%, and a steel slab composed of the remaining Fe and other unavoidable impurities to be heated, hot rolled and cold rolled, and cold rolled steel sheet In the method of producing a grain-oriented electrical steel sheet after the final annealing after recrystallization, the recrystallization annealing is a rapid heating step of increasing the temperature at an average heating rate of 300 ℃ / sec or more, and the average temperature rising in the rapid heating step after the rapid heating step It includes a rapid heating step of raising the temperature at an average temperature increase rate lower than the speed and higher than 100 ℃ / sec, and a general heating step of raising the temperature at an average temperature rising rate lower than the average temperature rising rate in the rapid temperature rising step after the rapid temperature rising step To a.

The present invention introduces a new three-stage temperature rising pattern (super rapid temperature rising, rapid temperature rising and general temperature rising) that is not existing during recrystallization annealing, and the temperature rising rate of 300 ° C./sec or more from room temperature to 500 to 600 ° C. temperature (Ts) before recrystallization. In the recrystallization section, the temperature is rapidly increased at 100 ~ 250 ℃ / sec, so that the deformation energy of the goth bearing in shear deformation is reduced, that is, the recovery is minimized, thereby maximizing nucleation of the goth bearing. It is intended to grow into recrystallized grains.

The Ts (° C.) is a temperature that is converted from the rapid ramping up to the rapid ramping up process, and typically, since recrystallization is started in a temperature range of about 550 to 600 ° C., Ts is 500 to 600 ° C., more preferably 550 to 600 It is preferable to set it to the temperature between ° C and below the recrystallization start temperature. The room temperature described above means the temperature of the steel sheet at the time when the temperature rising process is started in recrystallization annealing.

In addition, the present invention increases the fraction of the precision Goss bearing as a seed (seed) that can cause secondary recrystallization by the rapid heating process under the recrystallization temperature at the time of recrystallization annealing, nucleation of the highly integrated Goth bearing By inducing this, it was completed with new knowledge that the magnetic enhancement effect could be maximized.

In the case of re-crystallization annealing, if a normal temperature rising pattern is introduced in the temperature rising process after a rapid temperature rising, the volume fraction of the bearings falling within 15 ° from the {110} <001> bearing is only about 1%. On the contrary, in the present invention, in the temperature increase process during recrystallization annealing, the temperature is rapidly increased at an elevated temperature rate of 300 ° C./sec or more (preferably 400 ° C./sec or more) in a section ranging from room temperature to about 550 ° C. or less, and 570 ° C. or less. At a temperature of 100 to 250 ° C / sec or more (more preferably 120 to 180 ° C / sec or more) in a section that reaches a temperature of 700 ° C., and a temperature of 40 ° C. / When the temperature is elevated at a temperature rising rate of sec or less, it is possible to control the volume fraction of crystal grains having an orientation within 15 ° from the orientation of {110} <001> or more to 2% or more, in particular, {110} <001> or more. It is possible to control the volume fraction of the fine Goss grains having an orientation of 5 ° or less from the orientation to 0.09% or more.

The inventors raised the temperature at the time of recrystallization annealing, and in the sample where recrystallization immediately after rapid temperature rise was 95% or more, the range of 5 °, 10 °, and 15 ° in the orientation of {110} <001> or more in the lower layer by 1/8 of the total thickness from the surface. As a result of measuring the volume fraction of the crystal grains belonging to it, the total goth bearing is increased at the rapid temperature raising, and within 5 ° from the orientation of {110} <001> or higher in the recrystallization formed by the super rapid rising temperature + the rapid rising temperature + the general temperature rising. The maximum fraction of Goss orientation in the range, namely the exact Goss orientation, was observed.

As such, if the rate of increase of the orientation closer to the {110} <001> or higher orientation in the primary recrystallization structure, that is, the Exact Goss orientation, is higher than the increase rate of the orientation that deviates much from the orientation of the {110} <001> or higher orientation, The magnetic flux density and iron loss are greatly improved because it directly affects the integration density of the goth bearing, which acts as a nucleus and grows as a secondary recrystallized grain.

However, if the temperature increase rate is too fast during rapid temperature increase after the initial rapid temperature increase, the magnetism is rather deteriorated. The reason can be estimated as follows. In other words, when recrystallization annealing is applied to two-stage rapid heating (elementary rapid heating + rapid heating), the grain size distribution is uniform up to a specific heating rate, but the crystal grain is increased when the temperature rising rate is higher than 250 ℃ / sec from Ts to 700 ℃. The nonuniformity of is increased, so that the fraction having a grain size of 35 µm or more is excessively increased, and the magnetism worsens due to the growth of grains having poor orientation due to grain growth due to size advantage.

In addition, the goth bearing has high strain energy and is recrystallized first, and then {111} <112> and {411} <148> bearings are recrystallized. As the orientation fraction of {411} <148> increases gradually, the orientation growth of {111} <112> and {411} <148> can reduce the goth orientation during the primary recrystallization. It is not necessary to increase the temperature increase rate, and more preferably, it is preferable to heat at a temperature increase rate of 40 ° C./sec or less in a temperature section of 680 ° C. or higher.

Therefore, during the recrystallization annealing, the temperature rises from room temperature to Ts temperature at an initial temperature increase rate of 300 ° C./sec or higher, and then rapidly ramps up to 700 ° C. at an average temperature increase rate of 100 to 250 ° C./sec, and then 700 ° C. In the above temperature range, heating at an average temperature increase rate of 40 ° C./sec or less is an effective condition for increasing the fraction of the goth bearing to improve the magnetism.

Furthermore, the present inventors measured the area weighted average of angles deviating from the {110} <001> ideal orientation of the secondary recrystallized grains with respect to the specimen obtained by raising the temperature in the three-step heating pattern during recrystallization annealing. The main features of the measuring device used in the experiment are as follows. Based on the X-ray Laue method and measured with a fixed X-ray CCD detector, the X-ray diffraction occurs in the CCD detector and the specimen, and the tilt angle of the detector is controlled in 1 μm units so that no single crystal is subjected to deformation. The measurement accuracy was improved through the analysis of minimizing the orientation strain. While moving the specimen, measure the respective orientations at each position of the specimen, calculate the absolute value of the deviation angle from the ideal goth orientation at the orientation measured at each position, and then weight the area by weighting the area at all positions to obtain the absolute weight of the absolute value of the deviation angle. The average was measured.

The deviation angles were measured for four angles α, β, γ, and δ, and α angle was determined from the orientation of {110} <001> or more around the ND direction of the rolling plane of the secondary recrystallized texture. The mean deviation angle and β angle are mean deviation angles from the {110} <001> ideal orientation around the rolling right angle direction (TD) of the secondary recrystallized texture, and the γ angle is the rolling direction (RD) of the secondary recrystallized texture. The mean deviation angle from the {110} <001> ideal orientation in the circumference, δ angle, is defined as the average deviation angle between the <001> crystal orientation and the rolling direction RD in the secondary recrystallized texture.

As a result of the measurement, it was confirmed that all deviation angles become small when the two-stage rapid heating conditions of the super rapid heating and the rapid heating are applied at the time of recrystallization as in the present invention. In particular, it was confirmed that the area weighted average β angle exhibits a low value close to 2 °, and the δ angle also decreases rapidly. If the β angle has a low value close to 2 °, the magnetic field width is reduced to minimize the field energy, and the magnetism harmful to the magnet is minimized to improve the magnetism.

According to the manufacturing method of the grain-oriented electrical steel sheet according to the present invention as described above, when the value is measured for the steel sheet after the final annealing (secondary recrystallization annealing), β angle 1.5 as the area weighted average of the absolute value of the crystal orientation It is possible to control within an area of ˜2.6 °, more preferably within 1.5 to 2.4 °, and the angle δ can be controlled within an area of 5 °, more preferably within 4.5 °.

Hereinafter, the reason for component limitation of the grain-oriented electrical steel slab used in the present invention will be described.

[Si: 2.0 ~ 4.0 wt%]

Si increases the resistivity of the grain-oriented electrical steel sheet to lower core loss, that is, iron loss. If the Si content is less than 2.0%, the resistivity decreases and iron loss deteriorates. If the Si content exceeds 4.0%, the brittleness of the steel increases, making cold rolling difficult and unstable secondary recrystallization. Therefore, Si is set at 2.0 to 4.0%.

[Acid Soluble Al: 0.015 ~ 0.04 wt%]

Al finally becomes an AlN, (Al, Si, Mn) N type nitride and acts as an inhibitor. If the content is less than 0.015%, sufficient effect as an inhibitor cannot be expected. Adversely affects hot rolling workability. Therefore, Al is set at 0.015 to 0.04%.

[Mn: 0.20 wt% or less]

Mn also has the effect of increasing the specific resistance and reducing iron loss, similar to Si, and the growth of primary recrystallized grains by forming precipitates of (Al, Si, Mn) N by reacting with nitrogen introduced by nitriding with Si. It is an important element for suppressing and causing secondary recrystallization. However, when added in excess of 0.20%, the austenite phase transformation is promoted during hot rolling, thereby reducing the size of primary recrystallized grains, resulting in unstable secondary recrystallization. Therefore, Mn is made into 0.20% or less.

[C: 0.085 wt% or less]

C, when added in an appropriate amount, promotes austenite transformation of the steel to refine the hot rolled structure during hot rolling to help form a uniform microstructure. However, if the content is too large, coarse carbides are precipitated and it becomes difficult to remove carbon during decarburization. Therefore, C should be less than 0.085%.

[N: 0.010% or less]

N is an element which reacts with Al and the like to refine the crystal grains. If these elements are properly distributed, as described above, it may be helpful to secure an appropriate primary recrystallization grain size by appropriately finely structured after cold rolling, but if the content is excessive, the primary recrystallized grains are excessively finely formed. As a result, fine grains are not preferable because the driving force causing grain growth at the time of secondary recrystallization is increased, so that grains of undesirable orientation can be grown. When N is contained in an amount exceeding 0.010%, the secondary recrystallization start temperature is increased to deteriorate the magnetic properties. Therefore, N is set to 0.010% or less. In the case where the treatment of increasing the amount of nitrogen is carried out between cold rolling and final annealing (secondary recrystallization annealing), N of the slab is sufficient to be contained in 0.006% or less.

[S: 0.010% or less]

S is preferably an element which has a high solubility temperature and high segregation during hot rolling so as not to be contained as much as possible, but is an unavoidable impurity contained in steelmaking. In addition, since S forms MnS and affects the primary recrystallized grain size, the content of S is preferably limited to 0.010% or less, more preferably 0.006% or less.

[Sn, Sb, at least one selected from the group consisting of: 0.01% to 0.15%]

Sn, Sb, and P are grain boundary segregation elements, which segregate at the grain boundaries to inhibit crystal growth, thereby reinforcing the inhibitory power of precipitates. If the grain boundary segregation element is added too little, this effect is insufficient and the secondary recrystallization cannot be stably caused. Therefore, the total sum of these elements should be added to 0.01% by weight or more. And since de-elasticity may deteriorate and film property may be inferior, it is desirable to make sure that the sum total of these elements does not exceed 0.15 weight%.

In addition to the above components, it can be understood by those skilled in the art that various components included in the grain-oriented electrical steel sheet may be included as alloy components of the electrical steel sheet of the present invention. Commonly known combinations of components and their application are naturally within the scope of the present invention.

Hereinafter, a method for producing a grain-oriented electrical steel sheet having excellent magnetic properties using the grain steel slab having the above composition will be described in more detail.

The grain-oriented electrical steel slab having the above composition is subjected to a reheating process before hot rolling. At this time, it is preferable that the slab is heated at a low temperature of 1,280 ° C. or lower, more preferably 1,200 ° C. or lower to partially solidify the precipitate. If the heating temperature of the slab is increased, the manufacturing cost of the steel sheet is increased, and the melting of the surface of the slab can repair the heating furnace and shorten the life of the heating furnace. In particular, when the slab is heated to a temperature of 1,200 ℃ or less to prevent the coarse growth of the columnar structure of the slab to prevent cracks in the width direction of the plate in the subsequent hot rolling process to improve the error rate.

After the directional electric steel slab is reheated, hot rolling is performed. By hot rolling, a hot rolled sheet having a thickness of 2.0 to 3.5 mm can be manufactured. When the hot rolled sheet is manufactured, the hot rolled sheet is subjected to annealing as needed, followed by cold rolling. In the case of annealing the hot-rolled steel sheet, the steel sheet can be annealed by heating at a temperature of 1,000 to 1,250 ° C, followed by cracking at a temperature of 850 to 1,000 ° C, followed by cooling. The hot-rolled sheet annealing is performed according to need, and this can be omitted.

Cold rolling may be carried out through a single hot rolling, or may be carried out through two or more rollings with an intermediate annealing in between. Cold rolled steel sheet can be manufactured to final thickness.

It is preferable to control the plate temperature at 150-400 degreeC at the time of cold rolling. If the plate temperature is controlled to 150 ~ 400 ℃ during cold rolling, the invasive elements such as carbon or nitrogen may have a diffusion energy that can be fixed to the potential, and the strengthening may occur to increase the accumulation of strain energy. Therefore, it is possible to form a large number of shear deformation zones in the cold rolled sheet that serve as nucleation sites of the Goss orientation during primary recrystallization.

In addition, by introducing three steps of temperature rising patterns (super fast heating, rapid heating and general heating) in the temperature raising process of recrystallization annealing, the high Goss ({110} <001>) orientation is maintained up to the recrystallization temperature. It is possible to increase the volume fraction of the Goss orientation, in particular the Exact Goss orientation grains, on the recrystallized steel sheet, and to improve the crystal orientation density after the secondary recrystallization.

If the plate temperature is too low during cold rolling, it is better to set it to 150 ℃ or more because the movement of invasive elements is less, and if it is too high, the deformation energy decreases and the formation of shear band is rather reduced, so it is 400 ℃. It is good to set it as follows.

By adjusting the final thickness of the cold rolled sheet to 0.10 ~ 0.18mm, it is possible to manufacture a grain-oriented electrical steel sheet having excellent iron loss and magnetic flux density by dramatically improving the magnetism by reducing the eddy current loss due to the thickness decrease. As the thickness decreases, the secondary recrystallization may become unstable because the surface effect increases, but in the present invention, the secondary steel is added by adding at least one or more of Sn, Sb, and P segregation elements so that the total is 0.01 to 0.15% by weight. The secondary recrystallization was stably caused by improving the grain growth inhibition before recrystallization.

As such, despite the fact that it is an ultrathin product by strengthening the grain growth inhibition for secondary recrystallization, the secondary recrystallization is stably generated, and the magnetic properties are dramatically improved by reducing the eddy current loss due to the decrease in thickness. Can be prepared.

In addition, by adjusting the final thickness of the cold rolled steel sheet 0.35 ~ 0.50mm to increase the productivity in the transformer manufacturing, it is possible to manufacture a thick grain-oriented electrical steel sheet excellent in magnetic and noise characteristics.

The cold rolled steel sheet is then subjected to recrystallization annealing. As described above, the present invention is to introduce a new super-fast temperature rise in the temperature increase process during recrystallization annealing, it characterized in that the three steps of the temperature rising pattern of the rapid rising process, rapid temperature rising process and general temperature rising process in the temperature rising process during recrystallization annealing It is.

According to the present invention, a high-density goth ({110} <001>) orientation is maintained up to the first recrystallization temperature by introducing three steps of temperature rising patterns (super fast heating, rapid heating, and general heating) in the temperature raising process of recrystallization annealing. The volume fraction of the fine Goss orientation grains in the primary recrystallized steel sheet is increased to improve the crystal orientation density after the secondary recrystallization.

The average temperature increase rate of 300 ° C./sec or more in the range of temperature rise from 500 ° C. to 600 ° C., preferably from 550 ° C. to 600 ° C. Heating at a rapid rate, and in a rapid temperature increase process, the temperature is rapidly increased at an average temperature increase rate of 100 to 250 ° C / sec in a section from the specific temperature (Ts) to 700 ° C, followed by 40 ° C / By increasing the general temperature at an average temperature increase rate of sec or less, the magnetic properties of the grain-oriented electrical steel sheet can be improved, and the reason is as described above.

Although the heating method in the temperature raising process during recrystallization annealing is not particularly limited, it is possible to use an induction heating furnace, and it is also possible to increase the temperature in three temperature rising patterns by a plurality of induction heating furnaces. For example, in the first induction furnace, at a rate of temperature increase of 300 ° C./sec or more, preferably 400 ° C./sec or more, the superheat is rapidly increased, and in the second induction furnace, 100 to 250 ° C./sec, more preferably 120 to 120 ° C. Rapidly increase the temperature at a temperature increase rate of 180 ° C / sec, and can be normally raised in a third induction heating furnace at a temperature increase rate of 40 ° C / sec or less.

The elevated temperature steel sheet during recrystallization annealing undergoes decarburization and annealing. Nitride annealing may be made as a separate process after the decarburization is completed, it is also possible to nitrate at the same time as the decarburization.

In the case of annealing simultaneously with decarburization, it can be carried out in a mixed gas atmosphere of ammonia, hydrogen, and nitrogen. According to the method of decarburizing first and then nitriding after recrystallization annealing, precipitates such as Si ₃ N ₄ or (Si, Mn) N are formed in the surface layer of the steel sheet, and these precipitates are thermally unstable. Nitrogen annealing temperature should be controlled at 700 ~ 800 ℃ because it is easily decomposed and nitrogen diffusion occurs very quickly. Re-precipitation as precipitates such as AlN or (Al, Si, Mn) N, which is thermally stable during the final annealing process Only then can it act as an inhibitor. On the other hand, if decarburization and nitride annealing are performed at the same time, AlN or (Al, Si, Mn) N precipitates are formed at the same time, so it can be used as an inhibitor without transforming the precipitate during final annealing and thus does not require long processing time. Therefore, the method of simultaneously performing decarburization and annealing is more preferable.

However, the method for producing a grain-oriented electrical steel sheet of the present invention is not limited to the production by simultaneous decarburization and nitriding during recrystallization annealing, and the conventional nitride annealing method for performing nitride annealing after decarburization is also directed to the grain-oriented electrical steel having the advantageous characteristics of the present invention. It is effective for manufacturing steel sheet.

The first recrystallized steel sheet is subjected to annealing for a long time after application of the annealing separator to produce a second recrystallization, so that the {110} plane of the steel sheet is parallel to the rolling surface, and the <001> direction is parallel to the rolling direction. 001> Collective tissue is formed. The annealing separator may be preferably one produced based on MgO, but is not particularly limited thereto.

In general, the purpose of final annealing is to remove impurities that impair insulation and impair magnetic properties by forming {110} <001> texture by secondary recrystallization, glass coating by reaction of oxide layer formed by decarburization with MgO. As the final annealing method, the nitride is inhibited by keeping the mixed gas of nitrogen and hydrogen at the temperature rising period before the secondary recrystallization, and the secondary recrystallization is well developed. After completion of the secondary recrystallization, 100% hydrogen It is kept in the atmosphere for a long time to remove impurities.

Hereinafter, the present invention will be described in more detail with reference to Examples.

By weight, Si: 3.18%, C: 0.056%, Mn: 0.09%, S: 0.0054%, N: 0.0051%, Sol. A steel slab composed of Al: 0.028%, balance Fe, and other unavoidable impurities was heated at 1,150 ° C. for 210 minutes, followed by hot rolling to prepare a hot rolled plate having a thickness of 2.3 mm. The hot rolled sheet was heated to a temperature of 1,100 DEG C or more, held at 910 DEG C for 90 seconds, quenched in water, and then pickled, followed by cold rolling to a thickness of 0.30 mm. The cold rolled steel sheet was heated at a furnace speed and maintained at 845 ° C for 160 seconds in a mixed atmosphere of 65 ° C with a dew point temperature of 74.5% hydrogen, 24.5% nitrogen and 1% dry ammonia gas. It was. Nitrogen content of the nitrided steel sheet was controlled in the range of 170 ~ 210ppm. At this time, the temperature increase rate in the temperature range of room temperature ~ 570 ℃ and the temperature increase rate in the temperature range of 570 ℃ ~ 700 ℃ was varied as shown in Table 1. After heating at 700 ℃ to a decarbonization annealing temperature of 845 ℃ at a temperature increase rate of 30 ℃ / sec. This steel sheet was coated with MgO as an annealing separator, and finally annealed in a coiled state. The final annealing was performed at a mixed atmosphere of 25% nitrogen + 75% hydrogen up to 1,200 ° C. After reaching 1,200 ° C, the annealing was carried out in a 100% hydrogen atmosphere for 10 hours or more and then cooled. Table 1 shows the magnetic properties measured for each condition.

Room temperature ~ 570 ℃
Temperature rise rate
(℃ / sec) 570 ~ 700 ℃
Temperature rise rate
(℃ / sec) 700 ~ 845 ℃
Temperature rise rate
(℃ / sec) Magnetic flux density (B ₁₀ , Tesla) Iron loss
(W _17/50 , W / kg)
division 30 30 30 1.88 1.04 Comparison 1 30 140 30 1.92 0.96 Comparative material 2 30 270 30 1.91 0.97 Comparative material 3 30 350 30 1.90 1.00 Comparison 4 420 30 30 1.91 1.01 Comparative material 5 420 70 30 1.91 0.98 Comparative material 6 420 110 30 1.95 0.92 Inventory 1 420 140 30 1.96 0.90 Inventory 2 420 190 30 1.96 0.91 Inventory 3 420 270 30 1.92 0.97 Comparison 7 420 350 30 1.91 0.99 Comparative Material 8 560 30 30 1.91 1.00 Comparative material 9 560 70 30 1.92 0.97 Comparative material 10 560 110 30 1.94 0.92 Invention 4 560 140 30 1.97 0.89 Invention Article 5 560 190 30 1.96 0.91 Inventions 6 560 270 30 1.92 0.98 Comparative material 11 560 350 30 1.91 1.00 Comparative material 12 110 110 30 1.92 0.98 Comparative material 13

As shown in Table 1, the comparative materials 1 to 4 which are generally elevated (normally elevated) at a temperature increase rate of 30 ° C./sec in the range of room temperature to 570 ° C., have a magnetic flux density compared to the case where the initial temperature is elevated rapidly at a temperature increase rate of 560 ° C./sec. Low and high iron loss.

In addition, Comparative Material 13, which was heated at a temperature increase rate of 110 ° C./sec in a temperature range of room temperature to 700 ° C. during primary recrystallization, had a magnetic flux density of 1.92 (Tesla) compared to Inventive Materials 1 to 6 in one step rapid temperature increase (two temperature rising patterns). ) And iron loss is as high as 0.98 (W / kg).

On the contrary, the invention materials 1 to 6 controlled by the three-stage heating pattern by applying the two-stage rapid heating (initial rapid heating + rapid heating) conditions in the first recrystallization, as in the present invention, have a magnetic flux density of 1.94 to 1.97 (Tesla). High iron loss and low 0.89 ~ 0.91 (W / kg).

By weight, Si: 3.25%, C: 0.048%, Mn: 0.07%, S: 0.005%, N: 0.0045%, Sol. A steel slab made of Al: 0.027%, balance Fe, and other unavoidable impurities was heated at 1,150 ° C. for 210 minutes, and then hot rolled to prepare 1.7 mm, 2.0 mm, and 2.3 mm thick hot rolled plates. Each hot rolled sheet was heated to a temperature of 1,100 ℃ or more and then maintained at 910 ℃ for 90 seconds, quenched in water and pickled, and then cold rolled to a thickness of 0.23mm, 0.27mm, 0.30mm.

The cold rolled steel sheet was heated at a furnace speed and maintained at 845 ° C for 160 seconds in a mixed atmosphere of 65 ° C with a dew point temperature of 74.5% hydrogen, 24.5% nitrogen and 1% dry ammonia gas. It was. Nitrogen content of the nitrided steel sheet was controlled in the range of 170 ~ 210ppm. At this time, the temperature increase rate in the temperature range of room temperature ~ 570 ℃ and the temperature increase rate in the temperature range of 570 ℃ ~ 700 ℃ was varied as shown in Table 2. Thereafter, the temperature was raised to a temperature increase rate of 25 ° C./sec from 700 ° C. to 845 ° C. of decarbonization annealing temperature. This steel sheet was coated with MgO as an annealing separator, and finally annealed in a coiled state. The final annealing was carried out with a mixed atmosphere of 25% nitrogen + 75% hydrogen up to 1,200 ° C. After reaching 1,200 ° C, the annealing was maintained at 100% hydrogen atmosphere for at least 10 hours. Table 2 shows the magnetic properties measured for each condition.

Hot-rolled plate
thickness
[mm] Cold rolled plate
thickness
[mm] Room temperature ~ 570 ℃
Temperature rise rate
[° C / sec] 570 ~ 700 ℃
Temperature rise rate
[° C / sec] Magnetic flux density (B ₁₀ , Tesla) Iron loss
(W _17/50 , W / kg) division 1.7 0.23 30 30 1.91 0.90 Comparative material 14 1.7 0.23 140 140 1.93 0.86 Comparative material 15 1.7 0.23 560 30 1.92 0.88 Comparative material 16 1.7 0.23 560 140 1.96 0.75 Invention Material 7 1.7 0.23 560 350 1.92 0.88 Comparative Material 17 2.0 0.27 30 30 1.91 0.96 Comparative material 18 2.0 0.27 160 140 1.93 0.90 Comparative material 19 2.0 0.27 560 30 1.91 0.95 Comparative material 20 2.0 0.27 560 140 1.96 0.85 Invention Material 8 2.0 0.27 560 350 1.93 0.93 Comparative material 21 2.3 0.30 30 30 1.89 1.03 Comparative material 22 2.3 0.30 140 140 1.93 0.96 Comparative Material 23 2.3 0.30 560 30 1.91 1.00 Comparative Material 24 2.3 0.30 560 140 1.96 0.90 Invention Material 9 2.3 0.30 560 350 1.92 0.97 Comparative Material 25

As shown in Table 2, all of the invention materials 7 to 9 to which the temperature of the cold rolled sheet is 0.23mm, 0.27mm, and 0.30mm are applied to the temperature rising pattern condition of rapid temperature increase after the initial rapid temperature increase of the present invention when the primary recrystallization temperature is raised. Magnetic is excellent.

On the contrary, the comparative materials 14, 18, and 22 which are normally heated at a temperature increase rate of 30 ° C./sec in the range of room temperature to 570 ° C. are heated at a temperature increase rate of 140 to 160 ° C./sec in the range of room temperature to 700 ° C. The comparative materials 15, 19, and 23 obtained by increasing the temperature (two-step heating pattern) are less magnetic than the inventive materials 7 to 9, which are rapidly heated after the initial rapid heating.

By weight, Si: 3.25%, C: 0.052%, Mn: 0.105%, S: 0.0049%, N: 0.0048%, Sol. A slab of a grain-oriented electrical steel sheet composed of Al: 0.028%, balance Fe and other unavoidable impurities was heated at 1,150 ° C. for 210 minutes, and hot rolled to prepare a hot rolled sheet having a thickness of 2.3 mm. The hot rolled sheet was heated to a temperature of 1,100 DEG C or more, held at 910 DEG C for 90 seconds, quenched in water, and then pickled, followed by cold rolling to a thickness of 0.30 mm. The cold rolled steel sheet was heated at a furnace speed and maintained at 845 ° C for 160 seconds in a mixed atmosphere of 65 ° C with a dew point temperature of 74.5% hydrogen, 24.5% nitrogen and 1% dry ammonia gas. It was. Nitrogen content of the nitrided steel sheet was controlled in the range of 170 ~ 210ppm. At this time, the temperature increase rate in the temperature range of room temperature ~ 570 ℃ and the temperature increase rate in the temperature range of 570 ℃ ~ 700 ℃ was varied as shown in Table 3. After heating at 700 ℃ to a decarbonization annealing temperature of 845 ℃ at a temperature rising rate of 25 ℃ / sec. This steel sheet was coated with MgO as an annealing separator, and finally annealed in a coiled state. The final annealing was performed at a mixed atmosphere of 25% nitrogen + 75% hydrogen up to 1,200 ° C. After reaching 1,200 ° C, the annealing was carried out in a 100% hydrogen atmosphere for 10 hours or more and then cooled.

Table 3 shows the magnetic properties and goth orientation grain fraction measured for each condition. The goose-bearing grain fraction was measured by observing the thickness of 1/8 layer of the decarburized plate, and measured the deviation from the orientation of {110} <001> or higher within 5 ° and within 15 °. In addition, the number of grains having a size of 35 µm or more in the cross section perpendicular to the rolling direction of the decarburized plate and the grain fraction having an orientation within 15 ° from the {411} <148> orientation were measured and shown in Table 3 together. The grain size was taken as the average of the longest length and the shortest length.

Room temperature ~
570 ℃
Heating
speed
(℃ /
sec)
570 ~
700 ℃
Heating
speed
(℃ /
sec)
Magnetic flux
Density (B ₁₀ )
Iron loss
(W _17/50 ,
W / kg)
clay pipe
Crystal grain
amount
(35 μm
More than) {411}
<148>
Within 15 °
Bearing fraction
(%) Goss defense fraction


division Within 15 ° Within 5 °
(Exact Goss) defense
Fraction
(%) Comparative material
26 contrast
Growth rate Bearing fraction
(%) Comparative material
26 contrast
Growth rate 30 30 1.88 1.04 40 14.9 1.75 - 0.07 - Comparative Material 26 30 140 1.93 0.96 38 15.2 1.87 6.9 0.08 14.3 Comparative material 27 30 350 1.91 0.99 42 14.5 1.92 9.7 0.08 14.3 Comparative Material 28 560 30 1.91 0.99 35 14.8 1.85 5.7 0.08 14.3 Comparative Material 29 560 140 1.97 0.89 22 14.7 2.18 24.6 0.13 85.7 Inventions 10 560 190 1.95 0.91 27 16.0 2.34 33.7 0.12 71.4 Invention invention 11 560 350 1.92 0.97 42 16.0 2.34 33.7 0.12 71.4 Comparative Material 30 110 110 1.92 0.97 41 15.1 1.91 9.1 0.08 14.3 Comparative Material 31

As shown in Table 3, the comparative material 29 which increased the heating rate only in the temperature range of room temperature ~ 570 ℃ temperature, the comparative material 27, 28, the temperature increase temperature only in the temperature range of 570 ~ 700 ℃ and 570 ~ 700 ℃ All of the comparative materials 31 which increased the temperature increase rate in the temperature range increased the fraction of the Goss orientation somewhat compared to the comparative material 26, which was slower in the first recrystallization. The fractional increase of Exact Goss with an orientation within ° is very low at 14.3%. This can be explained from the fact that there is no significant change in the fraction of the {411} <148> orientation which is the main orientation among the grains of the {411} orientation during the primary recrystallization. In other words, when the temperature increase rate in the section of more than 570 ℃ is 140 ℃ / sec, the fraction of the {411} <148> orientation is slightly higher, the difference is less than 5%, and the {411} The growth of Goth defense is thought to have a modest impact on Exact Goss.

In contrast, inventive materials 10 and 11 belonging to the scope of the present invention had a volume fraction of more than 2% of grains having an orientation within 15 ° from an orientation of {110} <001> or higher, and in particular, directly increased the fraction of the Exact Goss orientation. This effect is very large, which can be seen from the fact that the gap between the invention and the comparative material becomes larger when the tolerance angle, which means the deviation from the goth azimuth ({110} <001>), is within 5 ° than when the angle is within 15 °. have.

That is, the invention material 10,11 which is heated up under the conditions of two-stage rapid temperature increase (high temperature rise in the range of 570-700 ° C after rapid increase in the temperature range from room temperature to 570 ° C) during recrystallization annealing as in the present invention is {110} <001> or more The volume fraction of the crystal grains having an orientation of 5 ° or less from the orientation is 0.09% or more, which is very different from the Goth orientation fraction of Comparative Materials 26-31. As such, according to the temperature raising condition of the present invention, the fraction of the bearings that are very close to the goth bearing, that is, the deviation (exact goss) that deviates within 5 ° from the {110} <001> or higher bearing, increases dramatically. Considering that the Goth grain is grown even if there is a very small amount of Goth bearing in the primary recrystallized grain, the Exact Goss bearing is dramatically increased, which increases the nucleus that can grow to the final direction, and this grows so that the second recrystallized bearing is It can be seen that the magnetism is very close to the orientation is improved.

When the temperature rise rate is higher than 250 ℃ / sec in the temperature range after the initial temperature increase during the recrystallization annealing, the goth bearing fraction is increased but the effect of improving the magnetism is not large. This is the steel sheet before the second recrystallization annealing after recrystallization annealing. Observing the cross-section of, the number of large grains larger than 35 μm excessively increases to 30 or more (Comparative Material 25), and the orientation that adversely affects the magnetism, not the goth, is caused by the size advantage. This is because many of the orientations of the final product version are out of orientation over {110} <001>.

By weight%, Si: 3.13%, C: 0.057%, Mn: 0.095%, S: 0.0045 N: 0.0049%, Sol. A steel slab composed of Al: 0.029%, balance Fe, and other unavoidable impurities was heated at 1,150 ° C. for 210 minutes, followed by hot rolling to prepare a hot rolled plate having a thickness of 2.3 mm. The hot rolled sheet was heated to a temperature of 1,100 DEG C or more, held at 910 DEG C for 90 seconds, quenched in water, and then pickled, followed by cold rolling to a thickness of 0.30 mm. The cold rolled steel sheet was heated at a furnace speed and maintained at 845 ° C for 160 seconds in a mixed atmosphere of 65 ° C with a dew point temperature of 74.5% hydrogen, 24.5% nitrogen and 1% dry ammonia gas. It was. Nitrogen content of the nitrided steel sheet was controlled in the range of 170 ~ 210ppm. At this time, the temperature increase rate in the temperature range of room temperature ~ 570 ℃ and the temperature increase rate in the temperature range of 570 ℃ ~ 700 ℃ was varied as shown in Table 4. After heating at 700 ℃ to a decarbonization annealing temperature of 845 ℃ at a temperature rising rate of 25 ℃ / sec. This steel sheet was coated with MgO as an annealing separator, and finally annealed in a coiled state. The final annealing was performed at a mixed atmosphere of 25% nitrogen + 75% hydrogen up to 1,200 ° C. After reaching 1,200 ° C, the annealing was carried out in a 100% hydrogen atmosphere for 10 hours or more and then cooled. Table 4 shows the magnetic properties measured for each condition. Also, after the second recrystallization of each specimen, the area weighted average of angles deviated from the {110} <001> ideal orientation of the grains was measured and shown in Table 4 together. Based on the X-ray Laue method and measured with a fixed X-ray CCD detector, the position is controlled in 1 µm increments to increase the measurement accuracy. Measure each bearing at each location, calculate the absolute value of the deviation angle with the ideal Goss direction from the direction measured at each location, and then calculate the area weighted average of the absolute values of the deviation angle at all locations. Measured.

Room temperature ~ 570 ℃
section
Temperature rise rate
(℃ / sec)
570 ~ 700 ℃ temperature range
Temperature rise rate
(℃ / sec)
Magnetic flux
density
(B ₁₀ , Tesla) Iron loss
(W _17/50 , W / kg)
In bearing over {110} <001>
Area weighted average of deviation angles division
alpha β γ δ 30 30 1.89 1.02 4.99 3.14 6.1 6.57 Comparative Material32 30 140 1.92 0.98 4.17 2.62 5.2 5.24 Comparative Material 33 30 350 1.91 0.99 3.89 2.84 4.52 5.27 Comparative Material 34 560 30 1.89 1.04 3.57 3.40 4.91 5.45 Comparative Material35 560 140 1.96 0.90 3.48 2.2 3.7 4.25 Invention 12 560 190 1.95 0.91 2.77 2.37 3.48 4.01 Invention invention 13 560 350 1.92 0.99 3.56 2.94 3.99 5.05 Comparative Material 36 110 110 1.92 0.98 3.49 2.64 4.03 5.01 Comparative Material 37

As shown in Table 4, Inventive Materials 9 and 10, which are rapidly warmed up after the rapid ramp-up as in the present invention, have an α angle of 3.48 ° or less, β angle of 1.5 to 2.4 °, gamma angle of 3.7 ° or less, and δ angle of 4.5. It was lower than °, especially the area weighted average β and δ angles are drastically lowered, improving the magnetism. This is directly related to the principle of improving magnetism in the present invention, since the magnetic domain width is minimized by the drastically lowered β and δ angles, thereby minimizing the electromagnetic energy of the field and at the same time minimizing Disclosure magnetic domains.

By weight%, Si: 3.17%, C: 0.053%, Mn: 0.078%, S: 0.0047%, N: 0.0049%, Sol. A slab of a grain-oriented electrical steel sheet composed of Al: 0.030%, Sn, Sb, P, balance Fe, and other unavoidable impurities was heated at 1,150 ° C. for 210 minutes, and hot rolled to prepare a 1.5 mm hot rolled sheet. The contents of Sn, Sb, and P were varied as shown in Table 5, and for some, Sn, Sb, and P were not added. The hot rolled sheet was heated to a temperature of 1,100 ° C. or more, held at 920 ° C. for 90 seconds, quenched in water and pickled, and then cold rolled to various thicknesses as shown in Table 5. Cold-rolled steel sheet was heated at a furnace speed and maintained at 850 ° C for 130 seconds in a mixed atmosphere of 65 ° C with a dew point temperature of 74.5% hydrogen, 24.5% nitrogen and 1% dry ammonia gas. It was. Nitrogen content of the nitrided steel sheet was controlled in the range of 170 ~ 210ppm. At this time, the temperature was raised to a temperature increase rate of 450 ℃ / sec in the temperature range of room temperature ~ 570 ℃, and heated at a temperature rising rate of 160 ℃ / sec in the temperature range of 570 ~ 700 ℃, then decarbonized annealing temperature at 700 ℃ 845 ℃ It heated up to the temperature increase rate of 20 degree-C / sec. This steel sheet was coated with MgO as an annealing separator, and finally annealed in a coiled state. The final annealing was performed at a mixed atmosphere of 25% nitrogen + 75% hydrogen up to 1,200 ° C. After reaching 1,200 ° C, the annealing was carried out in a 100% hydrogen atmosphere for 10 hours or more and then cooled. Table 5 shows the magnetic properties measured for each condition.

Sn
(weight%) Sb
(weight%) P
(weight%) Cold rolled thickness
(mm) Magnetic flux density
(B10, Tesla) Iron loss
(W17 / 50, W / kg) division - - - 0.06 1.71 1.90 Comparative Material 38 - - - 0.15 1.88 0.91 Comparative Material 39 0.04 0.02 0.025 0.18 1.96 0.70 Invention Article 14 0.04 0.02 0.025 0.15 1.96 0.62 Invention material 15 0.04 0.02 0.025 0.12 1.95 0.58 Invention material 16 0.04 0.02 0.025 0.06 1.88 0.88 Comparative Material40 0.09 0.08 0.04 0.15 1.75 1.83 Comparative Material41

As shown in Table 5, as the thickness of the cold roll becomes thinner, the secondary recrystallization may become unstable and the magnetism may be inferior. However, the inventive materials 14 to 16 added so that the sum of the Sn, Sb, and P contents is 0.01 to 0.15% by weight. As the secondary recrystallization stabilized, magnetism was significantly improved compared to the comparative material in the cold rolling thickness range of 0.10 to 0.18 mm.

Comparative materials 38 and 39 were inferior in magnetism due to the instability of secondary recrystallization because no grain boundary segregation element was added. Comparative material 40 had a cold rolled thickness of less than 0.10 mm, resulting in increased surface effect despite the addition of Sn, Sb, and P. Due to the instability of secondary recrystallization, magnetism was inferior, and comparative material 41 was inferior in magnetism due to excessive addition of grain boundary segregation elements.

By weight%, Si: 3.17%, C: 0.053%, Mn: 0.078%, S: 0.0047%, N: 0.0049%, Sol. A slab of a grain-oriented electrical steel sheet composed of Al: 0.030%, Sn, Sb, P, balance Fe, and other unavoidable impurities was heated at 1,150 ° C. for 210 minutes, and hot rolled to prepare a 2.6 mm hot rolled sheet. The contents of Sn, Sb, and P were varied as shown in Table 6, and for some, Sn, Sb, and P were not added. The hot rolled sheet was heated to a temperature of 1,100 ° C. or more, held at 920 ° C. for 90 seconds, quenched in water and pickled, and then cold rolled to various thicknesses as shown in Table 6. Cold-rolled steel sheet was heated at a furnace speed and maintained at 850 ° C for 130 seconds in a mixed atmosphere of 65 ° C with a dew point temperature of 74.5% hydrogen, 24.5% nitrogen and 1% dry ammonia gas. It was. Nitrogen content of the nitrided steel sheet was controlled in the range of 170 ~ 210ppm. At this time, the temperature was raised to a temperature increase rate of 450 ℃ / sec in the temperature range of room temperature ~ 570 ℃, and heated at a temperature rising rate of 160 ℃ / sec in the temperature range of 570 ~ 700 ℃, then decarbonized annealing temperature at 700 ℃ 845 ℃ It heated up to the temperature increase rate of 20 degree-C / sec. This steel sheet was coated with MgO as an annealing separator, and finally annealed in a coiled state. The final annealing was performed at a mixed atmosphere of 25% nitrogen + 75% hydrogen up to 1,200 ° C. After reaching 1,200 ° C, the annealing was carried out in a 100% hydrogen atmosphere for 10 hours or more and then cooled. Table 6 shows the magnetic properties measured for each condition.

Sn
(weight%) Sb
(weight%) P
(weight%) Cold rolled thickness (mm) Magnetic flux density (B10, Tesla) Iron loss
(W17 / 50, W / kg) Noise characteristics division - - - 0.40 1.88 1.17  usually Comparative Material42 0.04 0.02 0.025 0.40 1.94 1.04 Very good Invention 17 0.04 0.02 0.025 0.50 1.93 1.25 Very good Invention 18 0.04 0.02 0.025 0.70 1.89 1.76 usually Comparative Material43

As shown in Table 6, Inventive Materials 17-18 having a final cold rolling thickness of 0.35 to 0.50 mm and a total of Sn, Sb and P contents of 0.01 to 0.15% by weight not only have excellent noise characteristics compared to the comparative materials, It can be seen that the magnetic flux density is high and the iron loss is low.

Comparative material 42 was inferior in magnetism due to unstable secondary recrystallization because no grain boundary segregation element was added. Comparative material 43 was inferior in magnetism despite addition of Sn, Sb, and P in an appropriate amount because the cold rolling thickness exceeded 0.50 mm. It was.

Claims (8)

By weight%, Si: 2.0-4.0%, C: 0.085% or less, acid solubility Al: 0.015-0.04%, Mn: 0.20% or less, N: 0.010% or less, S: 0.010% or less, and Sn, Sb, P At least one or more selected from the group consisting of: 0.01 to 0.15%, consisting of residual Fe and other inevitable impurities, and the β weight is 1.5 to 2.6 ° as the area weighted average of the absolute values of the crystal orientation. The grain-oriented electrical steel sheet having excellent magnetic properties having a δ angle of 5 ° or less and a plate thickness of 0.10 to 0.50 mm.
The β angle is the mean deviation angle from the orientation of {110} <001> or more around the rolling right angle direction of the secondary recrystallized texture, and the δ angle is the average deviation angle between the <001> crystal orientation and the rolling direction of the secondary recrystallized texture. Means. By weight%, Si: 2.0-4.0%, C: 0.085% or less, acid solubility Al: 0.015-0.04%, Mn: 0.20% or less, N: 0.010% or less, S: 0.010% or less, and Sn, Sb, P At least one or more selected from the group consisting of: hot-rolled and cold-rolled steel slabs containing 0.01 to 0.15% of remainder Fe and other unavoidable impurities, followed by recrystallization annealing of the cold-rolled steel sheet Conduct annealing,
The recrystallization annealing is a rapid heating step of increasing the temperature at an average temperature increase rate of more than 300 ℃ / sec, and a rapid temperature rising rate of lower than the average temperature increase rate of the initial speed increase process after the rapid heating step at a higher temperature increase rate than 100 ℃ / sec And a general heating step of increasing the temperature at an average temperature increase rate lower than the average temperature increase rate in the rapid temperature increase process after the rapid temperature increase process. The method according to claim 2,
The rapid heating step is a rapid heating up at an average heating rate of 300 ℃ / sec or more in a section from room temperature to 500 ~ 600 ℃ temperature,
The rapid temperature increase process is rapidly heated at an average temperature increase rate of 100 ~ 250 ℃ / sec in a section from 500 ~ 600 ℃ temperature to 700 ℃,
The general temperature increase process is a method of producing a grain-oriented electrical steel sheet having excellent magnetic properties, characterized in that the temperature increase at an average temperature increase rate of 40 ℃ / sec or less in the section from 700 ℃ to decarbon annealing temperature. The method according to claim 3,
The rapid heating process is a rapid heating up at an average heating rate of 400 ℃ / sec or more in a section from room temperature to 500 ~ 600 ℃,
The rapid heating process is a method of producing a grain-oriented electrical steel sheet having excellent magnetic properties, characterized in that the temperature is rapidly raised at an average temperature rise rate of 120 ~ 180 ℃ / sec in a section from 500 ~ 600 ℃ temperature to 700 ℃. The method according to any one of claims 2 to 4,
The manufacturing method of the grain-oriented electrical steel sheet is a method of manufacturing a grain-oriented electrical steel sheet having excellent magnetic properties, comprising the step of heating the steel slab to a temperature of 1,280 ℃ or less before hot rolling. The method according to any one of claims 2 to 4,
Before the cold rolling, the hot rolled steel sheet is heated to a temperature of 1,000 ~ 1,250 ℃, then cracked at a temperature of 850 ~ 1,000 ℃ hot rolled sheet annealing, characterized in that the manufacturing method of excellent grain-oriented electrical steel sheet. The method according to any one of claims 2 to 4,
The cold rolling is a method of producing a grain-oriented electrical steel sheet having excellent magnetic properties, characterized in that the cold rolled sheet is performed so that the thickness of 0.10 ~ 0.50mm. The method according to any one of claims 2 to 4,
A method of producing a grain-oriented electrical steel sheet having excellent magnetic characterization, characterized in that the treatment is performed to increase the amount of nitrogen before the final annealing.