Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
  • C21D8/12—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
  • C21D8/12—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties
  • C21D8/1244—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties the heat treatment(s) being of interest
  • C21D8/1255—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties the heat treatment(s) being of interest with diffusion of elements, e.g. decarburising, nitriding
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
  • C21D8/12—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties
  • C21D8/1244—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties the heat treatment(s) being of interest
  • C21D8/1272—Final recrystallisation annealing
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
  • C21D9/46—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for sheet metals
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/001—Ferrous alloys, e.g. steel alloys containing N
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/008—Ferrous alloys, e.g. steel alloys containing tin
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
  • C23C8/02—Pretreatment of the material to be coated
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
  • C23C8/80—After-treatment
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
  • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
  • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
  • H01F1/12—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials
  • H01F1/14—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials metals or alloys
  • H01F1/16—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials metals or alloys in the form of sheets

Definitions

• the present invention relates to the manufacture of oriented electrical steel sheet used as a core material of electronic devices such as generators and transformers, by using Sn as the main grain growth inhibitors to increase the fraction of goth aggregates in the primary recrystallized texture, the final high temperature
• the present invention relates to a low iron loss high magnetic flux density oriented electrical steel sheet having improved magnetic properties by optimizing the secondary recrystallized grain size after annealing, and a method of manufacturing the same.
• a grain-oriented electrical steel sheet exhibits a Goss texture having a texture of ⁇ 110 ⁇ ⁇ 001> with respect to the rolling direction, and is a soft magnetic material having excellent magnetic properties in one direction or in the rolling direction.
• various process conditions such as component control in steelmaking stage, slab reheating and hot rolling process factor control in hot rolling, hot plate annealing, primary recrystallization annealing, and secondary recrystallization annealing are very precise and It must be strictly controlled.
• Inhibitor one of the factors expressing goth aggregates, is a grain growth inhibitor that suppresses indiscriminate growth of primary recrystallized grains and allows only goth aggregates to grow when secondary recrystallization occurs. To do. After the second recrystallization annealing, in order to obtain a final steel sheet having excellent goth aggregate structure, the growth of all primary recrystallization grains must be suppressed until the second recrystallization occurs, and the amount of inhibitor must be large enough to obtain sufficient restraining force. The distribution should also be uniform. In addition, in order for secondary recrystallization to occur during the high temperature secondary recrystallization annealing (final high temperature annealing), the thermal stability of the inhibitor should be excellent and not easily decomposed. Secondary recrystallization occurs when the inhibitor decomposes or loses restraining force at the appropriate temperature range during the final high temperature annealing. In this case, specific grains such as goth grains grow rapidly in a relatively short time.
• the quality of oriented electrical steel sheet can be evaluated by the magnetic flux density and iron loss, which are typical magnetic properties.
• high-quality directional electrical steel sheet is capable of manufacturing high-efficiency power equipment due to its characteristics, and thus, miniaturization of power equipment and high efficiency can be obtained.
• R & D for reducing iron loss of oriented electrical steel sheet was first made for R & D to increase magnetic flux density.
• the initial grain-oriented electrical steel sheet was MnS proposed by M. F. Littman as a grain growth inhibitor, and was produced by two cold rolling methods. According to this, secondary recrystallization was relatively stable, but the magnetic flux density was not so high and iron loss was high.
• Taguchi ( ⁇ ⁇ ) Al by using a combination of AlN, MnS precipitates as grain growth inhibitor, a technique for producing a grain-oriented electrical steel sheet by cold-rolling once at a cold rolling rate of more than 80%. It is a technique of obtaining a high magnetic flux density by improving the orientation of ⁇ 110 ⁇ ⁇ 001> azimuth in the rolling direction by a strong grain growth inhibitor and cold rolling, and it is possible to obtain low iron loss characteristics by greatly improving hysteresis loss. .
• reducing the thickness of the steel sheet is effective to reduce the iron loss by reducing the eddy current loss.
• This method can be obtained by adding deformation during cold rolling. In this case, since the driving force of grain growth is increased, the original grain growth inhibitor does not sufficiently suppress grain growth, and thus secondary recrystallization becomes unstable.
• rolling In order to reduce the thickness while balancing the grain growth driving force and the inhibitory force, rolling must be performed at an appropriate cold rolling rate during final cold rolling, and the appropriate cold rolling rate depends on the inhibitory power of the grain growth inhibitor.
• a technique of adding B and Ti has been proposed to reinforce the weakening of grain growth inhibition by one cold rolling.
• the technique of adding B is difficult to control in the steelmaking step by adding a small amount, and the added B is likely to form coarse BN in steel.
• the technique of adding Ti also acts as a factor to increase the iron loss as the TiN or TiC having a solid solution temperature of 1300 ° C or higher is present after the secondary recrystallization.
• Another method for improving grain growth inhibition is a technique for producing a grain-oriented electrical steel sheet using MnSe and Sb as a grain growth inhibitor.
• this method has the advantage of obtaining high magnetic flux density due to high grain growth suppression ability, but the material itself is considerably hardened, so it cannot be manufactured by one cold rolling, and thus two colds which are essentially passed through intermediate annealing. Since rolling must be performed and toxic and expensive Sb or Se are used, a separate facility for handling toxic substances is essential, which increases manufacturing costs.
• a grain-oriented electrical steel sheet was added by adding Sn and Cr in combination and heating the slab at a temperature of 1200 ° C. or below, followed by hot rolling, intermediate annealing, one or two cold rolling, and denitrification followed by nitriding using ammonia gas.
• a manufacturing method has been proposed. However, this has a very strict manufacturing standard for manufacturing low directional high magnetic flux density thin grain oriented electrical steel sheets, that is, the temperature of the hot-rolled sheet annealing process must be strictly controlled according to the acid-soluble Al and the content of the nitrogen-heated steel.
• Japanese Laid-Open Patent Publication No. 2006-241503 proposes a technique of improving the magnetic properties of an electrical steel sheet by adding elements such as Sb, P, Sn to the steel sheet.
• This technology specifically includes P: 0.015 ⁇ 0.07wt%, and if necessary, adds one or two selected from Sb: 0.005 ⁇ 0.2wt% and Sn: 0.01 ⁇ 0.5wt% to have stable magnetic properties. Suggesting.
• Japanese Patent Laid-Open No. 2007-254829 proposes a technique of adding Sb, P, and Sn alone or in combination. This suggests to improve the magnetic properties by containing 0.02 ⁇ 0.30wt% of Sn, Sb, P or more, if necessary.
• Japanese Patent Application Laid-Open No. 2007-051338 adds P to 0.2 wt% or less in steel and further includes at least one element selected from Sb: 0.001 to 0.02 wt% and Sn: 0.002 to 0.1 wt%.
• a method of manufacturing an electrical steel sheet is disclosed, and the magnetic property is characterized by excellent appearance in the 45 ° direction in the rolling direction.
• Japanese Laid-Open Patent Publication No. 11-335794 discloses the production of electrical steel sheet in which 0.0005 to 2.0% of one or more elements selected from elements such as Sb, P, Sn, B, Bi, Mo, Te, and Ge are added to the component system of the electrical steel sheet. A method is disclosed.
• alloying elements such as Sb, P, Sn, and B
• the range of alloying elements is generally described too broadly, respectively.
• the effect of the addition of the alloying elements alone is not the main, but most of the two or more of the alloying elements are described only to the extent that it contains at least one.
• a specific method for utilizing the above alloying elements as a major grain growth inhibitor is not proposed. That is, according to the current techniques, only the degree to which magnetism can be improved by adding at least one of alloy elements such as Sb, P, Sn, and B is known, and each element is used as a major grain growth inhibitor.
• Patent Document 1 JP2006-241503 A
• Patent Document 2 JP2007-254829 A
• Patent Document 3 JP2007-051338 A
• Patent Document 4 JP1999-335794 A
• the present invention has been made to solve all the problems of the prior art as described above, the purpose is to add Sn in the step of steel, but control in an appropriate range that can be utilized as a major grain growth inhibitor goth in the primary recrystallized structure
• the purpose of the present invention is to provide a low iron loss high magnetic flux density oriented electrical steel sheet and a method of manufacturing the same, which improves magnetism by increasing the fraction of aggregates and optimizing the size of secondary recrystallized grains.
• the present invention is to control the slab heating temperature to control the high capacity of the steel N, control the heating conditions before the decarburization annealing in order to maximize the effect of Sn as a major grain growth inhibitor, and decarburization to maintain the balance between the grain growth driving force and the inhibitory force It is an object of the present invention to provide a method for producing a grain-oriented electrical steel sheet having extremely excellent magnetic properties without causing a decrease in productivity by appropriately controlling annealing temperature conditions to form primary recrystallized grains of appropriate size.
• Low iron loss high magnetic flux density oriented electrical steel sheet manufacturing method of the present invention for solving the above problems by weight Si: 2.0 ⁇ 4.5%, Al: 0.005 ⁇ 0.040%, Mn: 0.20% or less, N: 0.010% or less, S: 0.010% or less, P: 0.005 to 0.05%, C: 0.04 to 0.07%, Sn: 0.08 to 0.10%, and after heating the slab composed of the remaining Fe and other unavoidably mixed impurities, hot rolling, After hot-rolled sheet annealing, followed by cold rolling, followed by decarburization and nitride annealing, followed by a second recrystallization annealing, characterized in that Sn is used as a major grain growth inhibitor.
• the decarburization and nitride annealing is carried out at a temperature range of 800 to 950 ° C. to control the size of the primary recrystallized grain to 18 to 25 ⁇ m, and is preferably maintained at a temperature of 600 ° C. or more and 700 ° C. or less at the time of temperature increase before decarburization annealing. It is particularly preferable that the temperature increase rate in the temperature range of 600 to 700 ° C. at a temperature increase before decarburization annealing be controlled to 1 ° C./s ⁇ [Sn(wt%)] or more and 12 ° C./s ⁇ [Sn(wt%)] or less. Do.
• the method for producing a grain-oriented electrical steel sheet of the present invention it is preferable to heat the slab before hot rolling at a temperature of 1050 to 1250 ° C., and to control the heating of the slab so that the solid solution of N is in the range of 20 to 50 ppm in the steel.
• the method for manufacturing a grain-oriented electrical steel sheet of the present invention is controlled so that the ⁇ angle is less than 3 ° as the area weighted average of the absolute value of the crystal orientation in the secondary recrystallized steel sheet, the average grain size of the secondary recrystallized steel sheet 1 ⁇ 2cm It characterized in that the control to be.
• Low iron loss high magnetic flux density oriented electrical steel sheet of the present invention for solving the above problems by weight Si: 2.0 ⁇ 4.5%, Al: 0.005 ⁇ 0.040%, Mn: 0.20% or less, N: 0.010% or less, S: 0.010% or less, P: 0.005 to 0.05%, Sn: 0.08 to 0.10%, and it is characterized by consisting of the remaining Fe and other unavoidable impurities.
• the grain-oriented electrical steel sheet of the present invention by weight, Si: 2.0 ⁇ 4.5%, Al: 0.005 ⁇ 0.040%, Mn: 0.20% or less, N: 0.010% or less, S: 0.010% or less, P: 0.005 ⁇ 0.05%, It can be produced using a slab containing C: 0.04 to 0.07%, Sn: 0.08 to 0.10% and consisting of the balance Fe and other unavoidable impurities.
• the grain-oriented electrical steel sheet of the present invention is characterized in that the ⁇ -angle is less than 3 ° as the area weighted average of the absolute value of the crystal orientation in the secondary recrystallized steel sheet, and the average grain size of the secondary recrystallized steel sheet is 1 to 2 cm.
• the Sn added in an appropriate amount acts as a major grain growth inhibitor, thereby increasing the fraction of Goth-bearing grains in the primary recrystallized texture, thereby increasing the degree of integration in the ⁇ 110 ⁇ ⁇ 001> orientation after the final secondary recrystallization. It is possible to manufacture ultra-low iron loss high magnetic flux density oriented electrical steel sheet composed of goth aggregate structure having high grain size and fine grain size.
• the present invention by controlling the content of N employed during slab reheating, controlling the temperature raising condition before decarburization annealing, maximizes the effect of Sn as a major grain growth inhibitor, and decarburization annealing in a temperature range slightly higher than normal conditions.
• N employed during slab reheating
• controlling the temperature raising condition before decarburization annealing maximizes the effect of Sn as a major grain growth inhibitor, and decarburization annealing in a temperature range slightly higher than normal conditions.
• the present inventors have studied and studied the effects of various alloying elements on the magnetism in the production of grain-oriented electrical steel sheet, and the effects of the processing conditions such as slab heating and decarburization annealing on the component system containing each alloying element.
• the processing conditions such as slab heating and decarburization annealing on the component system containing each alloying element.
• Sn was added as 0.08 ⁇ 0.10% by weight and used as the main grain growth inhibitor
• the fraction of Goth-bearing grains in the primary recrystallized texture increased and the ⁇ 110 ⁇ ⁇ 001> orientation after the final secondary recrystallization.
• secondary recrystallized structure composed of goth aggregated structure with very high integration density and fine grain size can be manufactured to produce oriented electrical steel sheet with extremely low iron loss and high magnetic flux density.
• the present inventors control the content of N employed in the reheating of the slab to 20 to 50 ppm in order to stably regenerate the secondary recrystallization using the slab of the component system in which Sn is added in the above composition range, and the Sn is a goth assembly structure.
• the present invention was completed by paying attention to the fact that the size of the primary recrystallized grains should be 18 to 25 ⁇ m.
• Sn acts as a major grain growth inhibitor, which segregates at grain boundaries other than Goth grains and hinders the movement of grain boundaries.
• Sn should be added in an appropriate amount of 0.08 to 0.10%.
• the appropriate amount of Sn is added, the ⁇ 110 ⁇ ⁇ 001> azimuth goose grain fraction of the primary recrystallized texture is increased to increase the degree of integration, and the nucleus of the goth defense grown to the secondary recrystallized texture is increased.
• the present invention uses a component-based slab to which the appropriate amount of Sn is added as described above, and when the slab is reheated, the slab heating temperature is controlled so that the solid solution of N is in the range of 20 to 50 ppm, and Sn is other grains except for Goth grains.
• the temperature is maintained at 600 ⁇ 700 °C before the decarburization annealing, and the decarbonized annealing temperature is controlled to maintain the balance between the driving force of the crystal growth and the restraining force.
• the size of the secondary recrystallized grain in the final product is 1 ⁇ 2cm, and as a result, the nucleation site of the goth assembly tissue is increased, and the ⁇ angle of the final steel sheet is less than 3 °, resulting in extremely excellent magnetic properties. It becomes possible to manufacture a grain-oriented electrical steel sheet.
• ⁇ angle is the deviation angle between the [100] direction and the rolling direction with respect to the rolling right angle direction of the secondary recrystallized texture.
• Si is a basic composition of electrical steel sheet to increase the specific resistance of the material serves to lower the core loss (core loss). If the Si content is less than 2.0%, the resistivity decreases, which leads to deterioration of iron loss characteristics and phase transformation between ferrite and austenite at high temperature annealing, resulting in not only unstable secondary recrystallization but also severely damaged texture. When the Si content exceeds 4.5%, the brittleness, which is the mechanical property of the electrical steel sheet, increases, and the toughness decreases, causing the occurrence of plate breakage during the rolling process, and unstable secondary recrystallization. Therefore, Si is preferably limited to 2.0 to 4.5% by weight.
• Al combines with Al, Si, and Mn in solid solution in the steel in which nitrogen ions introduced by ammonia gas in the annealing process after cold rolling, in addition to AlN precipitated finely during hot rolling and hot-rolled sheet annealing (Al, The formation of nitrides in the Si, Mn) N form serves as a powerful grain growth inhibitor.
• Al is less than 0.005%, since the number and volume of formation are considerably low, sufficient effect as an inhibitor cannot be expected.
• the content is more than 0.040%, Al forms coarse nitrides, thereby suppressing grain growth. Will fall. Therefore, the content of Al is limited to 0.005 ⁇ 0.040% by weight.
• Mn also has the effect of reducing the iron loss by increasing the specific resistance and reducing the eddy current loss, like Si, by reacting with the nitrogen introduced by the nitriding treatment with Si to form a precipitate of (Al, Si, Mn) N 1 It is an important element for causing secondary recrystallization by suppressing growth of secondary recrystallized grains.
• a large amount of (Fe, Mn) and Mn oxides are formed on the surface of the steel sheet in addition to Fe 2 SiO 4 , which hinders the formation of the base coating formed during high temperature annealing, thereby deteriorating the surface quality. Due to the phase transformation between ferrite and austenite in the process, the texture is severely damaged and the magnetic properties are greatly deteriorated. Therefore, Mn is made into 0.20 weight% or less.
• N is an important element that reacts with Al to form AlN and is preferably added at 0.010% by weight or less in the steelmaking step. If it is added in excess of 0.01% by weight, it causes surface defect called blister due to nitrogen diffusion in the process after hot rolling, and nitride is excessively formed in the slab state, making rolling difficult, complicated secondary process, and manufacturing cost. Because it raises, it suppresses below 0.01%.
• N needed to form nitrides such as (Al, Si, Mn) N and AlN is strengthened by nitriding in steel using ammonia gas in the annealing process after cold rolling.
• C is an element that causes phase transformation between ferrite and austenite. It is brittle and is an essential element for improving the rollability of electrical steel sheets. Since it is an element which worsens the magnetic property, it is preferable to control to an appropriate content.
• the C content is less than 0.04% in the above-described Si content, the phase transformation between ferrite and austenite does not work properly, causing unevenness of the slab and hot rolled microstructure. Therefore, the minimum content of C is preferably made 0.04% or more.
• C is preferably contained at most 0.07%.
• the content of S is preferably made 0.010% by weight or less.
• Sn is an alloy element, which is the core of the present invention, and acts as an inhibitor that segregates in the grain boundary and inhibits grain growth by preventing movement of the grain boundary.
• Sn is an alloy element, which is the core of the present invention, and acts as an inhibitor that segregates in the grain boundary and inhibits grain growth by preventing movement of the grain boundary.
• Sn plays an important role in suppressing grain growth through segregation at the grain boundary, which not only enhances the effect of suppressing the grain growth driving force of the refined primary recrystallized microstructure, but also for forming secondary recrystallized texture.
• Sn also compensates for the thermal instability of particles, which is pointed out as a problem of thin grain oriented electrical steel sheets having grain growth inhibition by grains in order to increase the rolling rate in order to reduce the thickness of the final product for thinning. Compensate for successful growth of the vehicular decision-making organization. Therefore, the addition of an appropriate amount of Sn increases the fraction of goth aggregates in the primary recrystallized texture, and increases the grain growth inhibitory ability, so that better texture, stable grain growth inhibition, and iron loss reduction due to thinning can be simultaneously obtained. As a result, it is possible to secure a secondary recrystallization aggregate structure composed of goth grains having a very high density.
• the results of the present inventors confirmed that the magnetic properties are improved, but the effect of improving the density of the Goth aggregate tissue is small, but rather to the particles present in the matrix. Due to the small effect of compensating for grain growth inhibition, the effect of improving magnetism was only minimal.
• Sn is contained in excess of 0.10% by weight, the grain growth inhibitory force is excessively increased, and the grain size of the primary recrystallized microstructure must be reduced in order to increase the grain growth driving force. As a result, it is difficult to control the proper oxide layer and a good surface cannot be secured. In addition, since the brittleness is increased due to excessive segregation of the grain boundary segregation element in terms of mechanical properties, it may cause plate breakage during the manufacturing process, and therefore, Sn is preferably contained in an amount of 0.08 to 0.10% by weight.
• P is an element exhibiting a similar effect to Sn, and may have a secondary role of segregating in the grain boundary to hinder the movement of the grain boundary and at the same time inhibiting grain growth, and improving the ⁇ 110 ⁇ ⁇ 001> aggregate structure in terms of microstructure. There is. If the content of P is less than 0.005% by weight, there is no effect of addition, and if it is added in excess of 0.05% by weight, brittleness is increased and rollability is greatly deteriorated.
• the grain-oriented electrical steel sheet manufactured by using the slab having the composition has a beta orientation ( ⁇ angle; TD orientation based on the TD orientation as one of azimuth relationship between the goth assembly structure and the rolling direction by increasing the nucleation site of the goth assembly structure).
• Azimuth between the azimuth and the RD azimuth is secured to within 3 ° and has extremely good magnetic properties.
• the slab is reheated prior to hot rolling, and the slab reheating is preferably carried out in a temperature range in which N and S to be in solution solidified.
• the slab is heated to a temperature at which N and S are completely dissolved, fine amounts of nitrides or sulfides are formed after the annealing of the hot rolled sheet. Therefore, cold rolling, which is a subsequent process, cannot be performed by one cold rolling.
• the production process is increased due to the additional process, and the size of the primary recrystallized grains becomes considerably fine, so that proper secondary recrystallization may not be expressed.
• the N employed by slab reheating influences the size and amount of additional AlN formed in the decarburization and nitriding annealing process. If the amount of AlN is the same, the amount of N formed increases and the grain growth inhibition is increased so that the goth aggregate structure is increased. It becomes impossible to obtain a suitable secondary recrystallized microstructure. On the contrary, if the amount of AlN is too small, the grain growth driving force of the primary recrystallized microstructure increases, so that it is impossible to obtain an appropriate secondary recrystallized microstructure similar to the above phenomenon. Therefore, it is preferable to control the slab heating conditions so that the content of N dissolved in the steel by the slab reheating is 20 ⁇ 50ppm.
• the content of N employed by slab reheating should take into account the content of Al in the steel cavity, since the nitrides used as grain growth inhibitors are (Al, Si, Mn) N and AlN.
• the correlation between the employment temperature and the solubility of Al and N in pure 3% silicon-containing steel sheet was proposed by Iwayama.
• the theoretical solid solution temperature T (K) is 1258 ° C, assuming that acid-soluble Al is 0.028% by weight and N is 0.0050% by weight.
• the slab of the steel sheet is heated to about 1300 ° C. Should be.
• iron olivine Fe 2 SiO 4 ; fayalite
• fayalite iron olivine
• the molten water causes the problem of repairing the furnace. Therefore, it is desirable to incomplete solution by reheating the slab to a temperature of 1050 ⁇ 1250 °C to reduce the downtime due to the repair of the furnace, and to enable the appropriate control of cold rolling and primary recrystallized texture.
• the slab is heated to a temperature in the above range, followed by hot rolling.
• the hot rolled hot rolled sheet there is a strain structure drawn in the rolling direction due to stress, and AlN or MnS is precipitated during hot rolling.
• the hot rolled sheet is heated to below slab heating temperature once again to recrystallize the deformed structure and to secure sufficient austenite phase to grow grains such as AlN and MnS. It is desirable to promote the employment of inhibitors. It is preferable to take such a method that the hot-rolled sheet annealing is heated to a temperature of 900 to 1200 ° C, subjected to a crack heat treatment, and then cooled in order to maximize the austenite fraction.
• the average size of precipitates in the steel sheet annealed hot-rolled is formed to have a range of 200 ⁇ 3000 ⁇ .
• cold rolling is performed using a reverse rolling mill or a tandem rolling mill to produce a cold rolled sheet of 0.10 mm to 0.50 mm.
• the low-density orientations of the ⁇ 110 ⁇ ⁇ 001> orientation are rotated in the deflection direction, and only the best aligned goth grains in the ⁇ 110 ⁇ ⁇ 001> orientation exist on the cold rolled plate.
• cold rolling is most preferably rolled so that the cold rolling rate is 87% or more by one cold rolling.
• This cold rolled plate is subjected to decarburization and annealing. This removes carbon below a certain level to prevent self aging, allows the deformed tissue to recrystallize, and nitriding with ammonia gas.
• nitrides such as (Al, Si, Mn) N and AlN, which are tin extracts, can be formed by introducing nitrogen ions into the steel sheet using ammonia gas. This nitriding treatment may be carried out after the decarburization and recrystallization, or may be carried out using ammonia gas simultaneously so as to carry out the nitriding treatment simultaneously with decarburization, either of which has no problem in achieving the effect of the present invention.
• the use of Sn as a major grain growth inhibitor is a technical idea, and for this purpose, it is necessary to allow Sn to segregate at the grain boundaries of other grains except for grains having a goth aggregate structure.
• the present inventors have conducted research and experiments on the process conditions that Sn can be effectively segregated at the grain boundaries of other grains except for the Goth-assembly grains, and Sn effectively grain boundaries at temperatures of 600 ° C to 700 ° C.
• the function as a major grain growth inhibitor can be maximized by maintaining the temperature at a temperature of 600 ° C. or higher and 700 ° C. or lower at the time of the elevated temperature before decarburization annealing.
• the maintenance heat treatment during the temperature raising process before decarburization annealing for the grain boundary segregation of Sn is carried out at a temperature range of 600 ° C to 700 ° C.
• the present inventors investigated the effect of the temperature increase rate before the decarburization annealing on the magnetic, the temperature increase rate in the 600 ⁇ 700 °C temperature range according to the content of Sn 1 °C / s ⁇ [Sn (% by weight)] or more 12 °C / The fact that it is desirable to control below sx [Sn (weight%)] was discovered.
• the temperature increase rate is less than 1 ° C / s ⁇ [Sn (wt%)] in the temperature range of 600 to 700 ° C before the decarburization annealing, the annealing time and the equipment become long enough to be unsuitable for commercial production. If the temperature increase rate exceeds 12 ° C / s ⁇ [Sn (wt%)] in the temperature range of 600 to 700 ° C before annealing, the particles are segregated to Sn to grain boundaries having a goth-assembly structure and have a goth-assembly structure. There arises a problem that the selective grain growth inhibition of the grains is lost.
• the present inventors pay attention to the fact that the balance between the grain growth inhibiting force and the grain growth driving force acts differently when the grain-oriented electrical steel sheet is to be manufactured using the slab containing Sn, and needs to be strictly considered.
• the balance of the grain growth driving force and the grain growth inhibiting force must be properly adjusted. We found that we should control the range from 18um to 25um.
• decarburization annealing is at least 10 ° C or more and 30 ° C or more than when using a slab composed of a conventional component system containing a lower Sn content than the present invention. It should be carried out at high temperature range.
• the effect of making the fine grains of the primary recrystallized grains and the segregation of the grains at the grain boundaries are enhanced at the same time. do.
• the size of the recrystallized grains is miniaturized, so that secondary recrystallization occurs well. Since the secondary recrystallization is less likely to occur, it is necessary to examine the decarburization annealing temperature condition by closely examining which factor is more predominant among the grain growth driving force and the grain growth suppression force.
• the present inventors have found that the increase factor of the grain growth driving force acts more strongly than the increase factor of grain growth inhibition in the component composition range of the present invention, so that secondary recrystallization tends to occur quickly. .
• the grain boundary segregation element Sn is added in the same content as in the present invention
• the decarburization annealing when the decarburization annealing is performed in a normal temperature range, the primary recrystallized structure becomes finer, and thus the grain growth driving force becomes stronger than when using the general component system. Therefore, decarbonization annealing needs to be performed at a temperature range higher than a normal temperature range to stabilize the primary recrystallized microstructure.
• the decarburization annealing temperature range needs to be set to 800 to 950 ° C., more preferably 850 to 950 ° C., at least 10 ° C. or more and 30 ° C. or more as compared with the conventional case. If the decarbonization annealing temperature is lower than 800 ° C, the size of the primary recrystallized grain becomes too small to increase the driving force for grain growth, and decarburization takes a long time due to annealing heat treatment at a low temperature, thereby lowering production.
• Fe 2 SiO 4 is formed on the surface of the steel sheet is very dense, the decarburization and internal oxide layer formation is delayed, the SiO 2 oxide layer is formed densely in a narrow area, the base coating defects occur.
• the decarbonization temperature exceeds 950 ° C, recrystallized grains and nitrides grow coarsely, so that the crystal growth driving force is excessively lowered so that a stable secondary recrystallization is not formed.
• the primary recrystallized grains are formed to have an appropriate size of 18 to 25 ⁇ m to obtain a suitable secondary recrystallization made of goth aggregate structure. .
• the ⁇ 110 ⁇ plane of the steel sheet is parallel to the rolled surface by applying an annealing separator based on MgO to the steel sheet, followed by final high temperature annealing, to cause secondary recrystallization.
• an annealing separator based on MgO to the steel sheet, followed by final high temperature annealing, to cause secondary recrystallization.
• the purpose of the final high temperature annealing is to form the ⁇ 110 ⁇ ⁇ 001> texture by secondary recrystallization, and to remove the impurities imparting insulation and damaging magnetic properties by forming a glassy film formed by the reaction of the oxide layer formed by decarburization with MgO.
• the secondary recrystallization is well developed by maintaining the mixed gas of nitrogen and hydrogen to protect the nitride which is a particle growth inhibitor, and after the secondary recrystallization is completed. Is kept in 100% hydrogen atmosphere for a long time to remove impurities.
• the grain-oriented electrical steel sheet manufactured by the above-described method using the slab having the composition range of the present invention is a beta orientation ( ⁇ angle), which is one of the orientation relations of the goth-assembly structure and the rolling direction by increasing the nucleation site of the goth-assembly structure.
• the angle between the [001] direction and the RD direction) is secured within 3 °, and the average grain size of the secondary recrystallized steel sheet is formed in a range of 1 to 2 cm, with extremely excellent magnetic properties.
• Si 3.2%, C: 0.055%, Mn: 0.099%, S: 0.0045%, N: 0.0043%, Sol.
• An ingot was prepared after vacuum melting of a slab containing Al: 0.028%, P: 0.028%, Sn, balance Fe, and other inevitable impurities. The content of Sn was changed as shown in Table 1 below. Then it was heated to a temperature of 1200 °C and hot rolled to a thickness of 2.3mm. The hot rolled hot rolled plate was heated to a temperature of 1050 ° C and then maintained at 950 ° C for 180 seconds to anneal and then water cooled.
• the hot-rolled annealing plate was cold rolled once to be 0.23mm thick after pickling, and the cold-rolled plate was maintained at a temperature of 870 ° C. for 180 seconds in a humid hydrogen, nitrogen, and ammonia mixed gas atmosphere so that the nitrogen content was 200 ppm.
• Inventive Materials 1 to 7 containing Sn in the range of 0.08 to 0.10% by weight are lower in iron loss and higher magnetic flux density than Comparative Materials 1 to 11.
• Si 3.2%, C: 0.055%, Mn: 0.099%, S: 0.0045%, N: 0.0043%, Sol.
• Ingots were prepared after vacuum melting of slabs containing Al: 0.028%, P: 0.028%, Sn, balance Fe, and other inevitable impurities. The content of Sn was changed as shown in Table 2 below. Then it was heated to a temperature of 1200 °C and hot rolled to a thickness of 2.3mm. The hot rolled hot rolled plate was heated to a temperature of 1050 ° C and then maintained at 950 ° C for 180 seconds to anneal and then water cooled.
• the hot-rolled annealing plate was pickled and cold-rolled once so as to have various thicknesses as shown in Table 2 below, and the cold-rolled plate was maintained at 870 ° C. for 180 seconds in a humid hydrogen, nitrogen, and ammonia mixed gas atmosphere.
• the decarburization and nitriding were carried out simultaneously so that the nitrogen content was 200 ppm.
• MgO an annealing separator, was applied to the steel sheet, followed by final annealing onto a coil.
• the final annealing was carried out at a mixed atmosphere of 25% nitrogen + 75% hydrogen up to 1200 ° C. After reaching 1200 ° C, the final annealing was carried out in a 100% hydrogen atmosphere for 10 hours or more, followed by quenching.
• Magnetic properties (W 17/50 and B 8 ) were measured for each condition and are shown in Table 2 below.
• the water-cooled hot-rolled annealing plate was pickled and then cold-rolled once to be 0.23 mm thick.
• the cold rolled plate was maintained at a temperature of 870 ° C. for 180 seconds in a humid atmosphere of mixed hydrogen, nitrogen, and ammonia, and simultaneously decarburized and nitrified to a nitrogen content of 200 ppm.
• MgO an annealing separator, was applied to the steel sheet, followed by final annealing onto a coil.
• the final annealing was carried out at a mixed atmosphere of 25% nitrogen + 75% hydrogen up to 1200 ° C. After reaching 1200 ° C, the final annealing was carried out in a 100% hydrogen atmosphere for 10 hours or more, followed by quenching.
• Magnetic properties (W 17 / 5O , B 8 ) were measured for each condition and are shown in Table 3 below. Also, after calculating the absolute value of the angle deviating from the ⁇ 110 ⁇ ⁇ 001> ideal orientation of the secondary recrystallized grains, the weight-averaged area is measured at all positions, and the ⁇ angle is measured. Together.
• the secondary recrystallized grain size is calculated by dividing the maximum length and the shortest length of the secondary recrystallized microstructures observed on the surface of the secondary recrystallized steel plate in half and calculating the size of each secondary recrystallized grain, The size of the vehicle recrystallized grains was calculated as an average value.
• Inventive Materials 2, 4, 6, and 7 containing Sn in the range of 0.08 to 0.10% by weight are the final steel sheets showing the degree of deviation from the goth bearing due to the effect of increasing the nucleation site of the goth assembly tissue.
• the beta angle of is less than 3 °, the orientation is greatly improved, and the secondary recrystallized grains are formed to an appropriate size of 1 to 2 cm, which is excellent in magnetism, but Comparative materials 2 to 8 and 11, in which Sn is out of the scope of the present invention, are final.
• the beta angle of the steel sheet exceeded 3 ° and the magnetic inferiority.
• the water-cooled hot-rolled annealing plate was pickled and then cold-rolled once to be 0.23 mm thick.
• the cold rolled plate is heated up at 600 °C to 700 °C while raising the temperature to 865 °C, and maintained at 865 °C for 180 seconds in humid hydrogen, nitrogen and ammonia mixed gas atmosphere.
• Simultaneous decarburization and nitriding annealing were carried out to 200 ppm.
• MgO an annealing separator, was applied to the steel sheet, followed by final annealing onto a coil. The final annealing was carried out at a mixed atmosphere of 25% nitrogen + 75% hydrogen up to 1200 ° C.
• the final annealing was carried out in a 100% hydrogen atmosphere for 10 hours or more, followed by quenching.
• the heating rate and the magnetic properties measured after final annealing (W 17 / 5O , B 8 ) measured in the temperature range from 600 °C to 700 °C during decarburization and nitride annealing are shown in Table 4.
• Sn is contained in the range of 0.08 to 0.10% by weight, and the temperature increase rate in the temperature range of 600 to 700 ° C during decarburization and annealing is 1 ° C / s ⁇ [Sn (% by weight)] or more.

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