JPH0577749B2 - - Google Patents

Description

[Detailed description of the invention]

(Field of industrial application) Among the improvements in the electrical and magnetic properties of grain-oriented silicon steel sheets, remarkable development efforts have been made in recent years to meet the extreme requirements of reducing iron loss. are being listed. In this specification, the following is related to the results of development research that will lead to a new method that can advantageously satisfy the above requirements, particularly regarding the magnetostrictive compressive stress properties of unidirectional silicon steel sheets among the above properties. I will explain. As is well known, unidirectional silicon steel sheets are products in which secondary recrystallized grains are highly concentrated in the (100) [001], or Goss, orientation, and are mainly used in transformers and other electrical equipment. Used as an iron core, the product has a high magnetic flux density (represented by B ₁₀ ) as an electric/magnetic property, and has a low iron loss (W _17/50) .
In addition to having a low value (represented by the value of This unidirectional silicon steel plate is manufactured through a complex and diverse process, and numerous improvements have been made over the years, and today products with a thickness of 0.30mm have magnetic properties of B ₁₀ 1.90T or higher, W _{17/ 50} 1.05W/
Kg or less, and the magnetic properties of products with a plate thickness of 0.23 mm are
B ₁₀ 1.89T or more, W _17/50 0.90W/Kg or less ultra-low core loss unidirectional silicon steel sheets are being manufactured, and these are excellent B ₁₀ and W _17/50 As will be explained in detail, this invention has newly discovered an ultra-thin tension coating that is useful for improving the magnetostrictive compression properties of unidirectional silicon steel sheets. In general, magnetostriction in silicon steel sheets is a phenomenon in which the steel sheet expands and contracts when it is magnetized, and is the largest cause of transformer noise. This magnetostrictive behavior is due to the fact that the magnetization process of the steel sheet includes 90° domain wall movement and rotational magnetization, and the magnetostriction increases in accordance with the compressive stress applied to the steel sheet. When assembling a transformer, compressive stress is inevitably applied to the steel plate, so it is advantageous in terms of magnetostrictive compressive stress characteristics if tension is applied to the steel plate in advance. Of course, applying tension to the steel plate is also effective in improving the iron loss of the grain-oriented silicon steel plate, and the effect is significant. In general, grain-oriented silicon steel sheets are annealed mainly with iron oxides called fireite (Fe ₂ SiO ₄ ), which are formed on the steel sheet surface during decarburization and primary recrystallization annealing before secondary recrystallization, and MgO. Tension is applied by the forsterite base film produced by a high-temperature reaction during final annealing with a separating agent, and a baked film containing phosphate and colloidal silica as main components, which causes magnetostriction. Although the characteristics have been improved, the improvement of the compressive stress characteristics of magnetostriction by such conventional methods is not necessarily sufficient. (Prior art) Development of an insulating film that can apply elastic tension to the surface of a steel plate in order to improve magnetostrictive properties.
56-521117 or Japanese Patent Publication No. 53-28375), but they are still ineffective. (Problems to be Solved by the Invention) It is possible to provide a tensile coating that can further advantageously improve the compressive properties of magnetostriction in a unidirectional silicon steel sheet, together with an effective reduction in core loss. The purpose of this invention is to make it practical to improve the electric and magnetic properties, and here the thin layer of TiN, TiC or Ti (CN) is applied to the surface of the grain-oriented silicon steel sheet to form a strong and strong layer. This is derived from the new finding that by coating in close contact, it is possible to improve the magnetostrictive compression properties as well as reduce iron loss. (Means for Solving the Problems) This invention consists of an ultra-thin layer of at least one of TiN, TiC, and Ti(CN), and the surface of a finish-annealed unidirectional silicon steel sheet has a centerline average roughness. 0.4μm
This is an ultra-thin tensile coating that improves the magnetostrictive compressive stress characteristics of unidirectional silicon steel sheets, and is characterized by being coated in close contact with the finished mirror surface. In practice, it is necessary to superimpose this ultra-thin tension coating by applying a baked coating based on phosphate and colloidal silica to provide electrical insulation. The explanation will begin with the experimental results that led to the success of this invention. C: 0.045% by weight (hereinafter simply expressed as %), Si3.38
%, Mn: 0.063%, Se: 0.021%, Sb: 0.025%,
Silicon steel cast slab containing Mo: 0.025%,
After heating at 1340°C for 4 hours, it was hot rolled to obtain a 2.0 mm thick hot rolled sheet. Thereafter, after uniform annealing at 900°C for 3 minutes, cold rolling was performed twice with intermediate annealing at 950°C for 3 minutes to obtain a final cold-rolled sheet with a thickness of 0.23 mm. After that, decarburization and primary recrystallization annealing were performed using wet hydrogen casting at 820°C, and Al ₂ O ₃ (70%) and MgO (30%) were added to the surface of the steel sheet.
%) is applied as the main component, and then
Secondary recrystallization annealing was performed at 850°C for 50 hours and blunting annealing was performed at 1200°C in dry hydrogen for 5 hours. After that, the steel plate surface was first pickled in 50°C HCl solution to remove oxides on the steel plate surface, and then chemically polished in a solution of 3% HF and H ₂ O ₂ to give the steel plate surface a center line average roughness of 0.05μ.
Finished with a mirror finish of m. Thereafter, a TiN tension thin film with a thickness of 0.7 μm was formed by a CVD reaction on the surface of the steel plate at 750° C. for 20 hours in a mixed gas atmosphere of TiCl ₄ , H _{2 ,} and N ₂ using a CVD device. Thereafter, an insulating film containing phosphate and colloidal silica as main components was formed on the surface of the steel plate by baking, and then strain relief annealing was performed at 800°C for 2 hours to produce a product. Figure 1 shows the magnetostrictive compressive stress characteristics and magnetic characteristics of this product in comparison with a normally processed material (comparative material). The comparison material used here was a part of the final cold-rolled sheet with a thickness of 0.23 mm, which was decarburized and treated in wet hydrogen at 820°C.
After the next recrystallization annealing, the surface of the steel plate shows
After applying an annealing separator mainly composed of MgO, secondary recrystallization annealing was performed at 850℃ for 50 hours.
Regarding the annealing in dry hydrogen at 1200℃ for 5 hours, and the baking of the insulating coating mainly composed of phosphate and colloidal silica, which is superimposed on the forsterite base coating formed on the steel plate surface at this time. The same procedure was used for the sample materials listed above. As is clear from Figure 1, the magnetic properties of the product coated with the TiN ultra-thin tensile coating of this invention are B _10.
is 1.92T, W _17/50 is 0.69W/Kg, which is extremely good.
Moreover, even if the compressive stress is increased to 0.6 Kg/mm ² , the increase in magnetostriction λpp is extremely small. On the other hand, the magnetic properties of products made from normal process materials (comparison materials) are 1.90T for B ₁₀ and 0.87W/Kg for W _17/50 .
Moreover, the more compressive pressure is applied, the more the magnetostriction λpp
For example, when the compressive stress σ is 0.4 Kg/mm ^{2 ,} the magnetostriction λpp reaches a large value of 3.2×10 ⁻⁶ . Subsequently, the inventors conducted extensive experiments to determine whether an ultra-low core loss unidirectional coarse steel sheet having excellent magnetostrictive compressive stress characteristics as described above could be obtained even when the product sheet thickness was different. That is, C0.042%, Si3.38%, Mn0.062%,
A continuously cast silicon steel slab containing 0.021% Se, 0.025% Sb, and 0.025% Mo was heated at 1360° C. for 5 hours and then hot rolled into a hot rolled plate having a thickness of 1.8 to 3.0 mm. After that, the hot-rolled plates of different thicknesses were uniformly annealed at 900℃ for 3 minutes, and then cold-rolled twice with intermediate annealing at 950℃ for 3 minutes.
The final cold rolled sheets were obtained grouped into 0.27, 0.30 and 0.35 mm thickness. After decarburization and primary recrystallization annealing in wet hydrogen at 820°C, Al ₂ O ₃ (70%) is deposited on the surface of the steel sheet.
An annealing separation material mainly composed of MgO (30%) is applied, followed by secondary recrystallization annealing at 850℃ for 50 hours.
A blunting annealing was performed at 1200°C in dry hydrogen for 5 hours. After that, the steel plate surface was first pickled in HCl solution at 70°C to remove oxides on the steel plate surface, and then chemically polished in a solution of 3% HF and H ₂ O ₂ to give the steel plate surface a center line average roughness of 0.05μ.
Finished with a mirror finish of m. Thereafter, using a PVD (ion plating) device, ultrathin tension coatings with various thicknesses ranging from 0.005 to 3 μm were formed on the surface of the steel plate. After that, an insulating film mainly composed of phosphate and colloidal silica is formed on the surface of the steel plate by baking, and then strain relief annealing is performed at 800°C for 2 hours to produce a product. The results of measuring the characteristics are summarized in Figure 2. Figure 2 shows the relationship between product thickness and tension coating thickness, together with the iron loss value for each product thickness, so that the magnetostriction of the product is 0.5×10 ^-6 λpp or less when the compressive stress is 0.4Kg/ ^mm2 . . As is clear from Figure 2, in order to obtain a unidirectional silicon steel sheet with excellent magnetostrictive properties as well as iron loss value,
It can be seen that there is a correlation between the product board thickness and the TiN film thickness, and it is necessary to reduce the TiN film thickness for products with thin product board thickness, and to increase the TiN film thickness for products with thick product board thickness. (Function) The reason why the magnetostrictive compressive stress characteristics and magnetic properties are improved by forming an ultra-thin tension film of TiN after mirror-finishing a finish annealed unidirectional silicon steel sheet as described above is that mirror-finishing improves the magnetic domain wall. This is thought to be because strong elastic tension was applied to the steel plate by forming a TiN tension coating with excellent adhesion to the steel plate while making it easy to move. this
The optimal thickness of the TiN tension coating depends on the thickness of the product board, and for thick products, it is necessary to increase the tension by increasing the TiN film thickness. The tensile stress applied to silicon steel sheets in this way is effective not only for magnetostriction but also for improving iron loss, and is particularly effective in the case of high magnetic flux density unidirectional silicon steel sheets that are strongly concentrated in the gas direction. Remarkable. Next, a unidirectional silicon steel sheet and its manufacturing process according to the present invention will be explained. The starting material is conventionally known unidirectional silicon steel material components, such as C: 0.03-0.05%, Si: 2.50-4.5% Mn: 0.01-0.2%, Mo: 0.003-0.1% Sb: 0.005-0.2%, S or Se type 1 or 2
Composition containing 0.005-0.05% in total of species C: 0.03-0.08%, Si: 2.0-4.0% S: 0.005-0.05%, N: 0.001-0.01% Al: 0.01-0.06%, Sn: 0.01-0.5 %, cu: 0.01~0.3%, Mn: 0.01~0.2% C: 0.03~0.06%, Si: 2.0~4.0% S: 0.005~0.05%, B: 0.0003~0.004%, N: 0.01~ Composition containing 0.05%, Mn: 0.01-0.2%, C: 0.03-0.05%, Si: 2.0-4.0% Se: 0.005-0.05%, Sb: 0.005-0.2% Composition containing C: 0.03-0.05% , Si: 2.0 to 4.0%, S: 0.005 to 0.05%, and Mn: 0.01 to 0.2%.Next, the hot-rolled sheet is uniformly annealed at 800 to 1100°C once. The final thickness is obtained by cold rolling the final thickness, or the two-step cold rolling method involves intermediate annealing between 850℃ and 1050℃, followed by further cooling.In the latter case, the initial rolling reduction is Approximately 50% to 80%, final reduction rate is 50
The final cold-rolled plate thickness is 0.15mm to 0.35mm at a rate of 85% to 85%. After the final cold rolling, the steel plate finished to the product thickness is degreased on the surface and then subjected to decarburization and primary recrystallization annealing in wet hydrogen at 750°C to 850°C. After that, Al ₂ O ₃ , ZrO ₂ or TiO ₂ was applied to the surface of the steel plate.
Apply an annealing separator mainly composed of MgO, etc.
The present invention is applicable regardless of whether forsterite is formed or not. It is especially effective not to form forsterite, which has traditionally been indispensable to be formed after finish annealing, in order to simplify the subsequent mirror finishing of the steel sheet, so Al ₂ O ₃ ,
It is preferable to use 50% or more of ZrO ₂ , TiO ₂ or the like mixed with MgO. After that, secondary recrystallization annealing is performed, but this process is performed to sufficiently develop secondary recrystallized grains with {110} <001> orientation, and is usually box annealed immediately at a temperature of 1000℃ or higher. This is done by heating and holding at that temperature. In this case, in order to develop a highly uniform secondary recrystallized grain composition in the {110}<001> orientation, it is advantageous to perform retention annealing at a low temperature of 820°C to 900°C.
In addition, slow heat annealing at a heating rate of 0.5 to 15° C./h may also be used. For annealing after secondary recrystallization, it is necessary to perform annealing in dry hydrogen at 1100° C. or higher for 1 to 20 hours to dull the steel sheet. After this blunt annealing, the oxide film on the surface of the steel sheet is removed by known chemical removal methods such as pickling, mechanical removal methods such as cutting and polishing, or a combination thereof. After this oxide removal treatment, conventional methods such as chemical polishing such as chemical polishing and electrolytic polishing, mechanical polishing such as buffing, or a combination thereof are used to polish the steel plate surface to a mirror-like state, that is, to a center line average roughness of 0.4 μm or less. Finish it. After such mirror polishing, one of TiN, TiC or Ti(CN) is removed by CVD, ion plating or ion implantation.
Forms an ultra-thin tensile film consisting of more than one species. As is clear from Figure 2, the optimal film thickness of the coating at this time varies depending on the product board thickness, and thicker products require a thicker film, while thinner products require a thinner film. . Furthermore, an insulating film containing phosphate and colloidal silica as main components is baked on the tension film thus produced, and then subjected to strain relief annealing in a temperature range of 600 to 900°C to produce a product. (Example) Example 1 (a) C: 0.042%, Si: 3.36%, Mn: 0.062%,
Mo: 0.024%, Se: 0.021%, Sb: 0.025%, (b) C: 0.056%, Si: 3.36%, Mn: 0.068%,
Al: 0.026%, S: 0.029%, N: 0.0069%,
Hot rolled sheets containing C: 0.1% and Sn: 0.05% were prepared. First, the hot-rolled sheet (a) was uniformly annealed at 900°C for 3 minutes and then cold-rolled twice with an intermediate annealing at 950°C to obtain a final cold-rolled sheet with a thickness of 0.20 mm. On the other hand, the hot-rolled sheet (b) was uniformly annealed at 1080°C for 3 minutes and then rapidly cooled, and then warm-rolled at 300°C to form a final cold-rolled sheet with a thickness of 0.20 mm. After that, all cold-rolled sheets were decarburized and annealed in wet hydrogen at 830℃, and Al ₂ O ₃ (75%) and MgO were added to the steel sheet surface.
(20%) and ZrO ₂ (5%) as the main components, the sample made of material (a) was heated at 850℃ for 50℃.
After secondary recrystallization annealing for 5 hours, the sample made of material (b) was annealed in dry hydrogen at 1200℃ for 5 hours and was heated from 850℃ to 1050℃ at 5℃/hr for secondary recrystallization. Afterwards, each was subjected to blunt annealing in dry hydrogen at 1200°C for 8 hours. Thereafter, the oxide film was removed by pickling, and then chemical polishing was performed in a 3% HF and H _{2 O} solution to give a mirror finish. After that, using a CVD device, (i) a thin film of TiN is formed from a mixed gas of TiCl ₄ , H ₂ and N ₂ , (ii) a thin film of TiCl ₄ , H ₂ and N ₂ is formed.
A thin film of Ti( _CN ) and (iii)
A thin film of TiC was formed using a mixed gas of TiCl ₄ , H ₂ , N ₂ and CH ₄ to a thickness of 0.7 μm. Also, using ion plating and ion implantation equipment, 0.7
A thin film with a thickness of ~0.9 μm was formed. After that, the surface of these treated samples was baked with an insulating coating mainly composed of phosphate and colloidal silica, and then subjected to strain relief annealing at 800°C for 2 hours. Table 1 shows the magnetic properties and magnetostrictive compressive stress properties (values of magnetostrictive λpp under compressive stress σ of 0.4 and 0.6 Kg/mm ² ) of the product at that time.

[Table] Example 2 C: 0.043%, Si: 3.42%, Mn: 0.069%, Se:
After heating unidirectional silicon steel containing 0.021%, Sb: 0.025%, and Mo: 0.025% at 1400°C for 3 hours,
It was hot rolled into a hot rolled sheet with a thickness of 1.8 to 2.7 mm. Then, after uniform annealing at 900℃ for 3 minutes, cold rolling was performed twice with intermediate annealing at 950℃ for 3 minutes.
The final cold rolled sheets were 0.20, 0.23, 0.27 mm and 0.30 mm thick. After that, primary recrystallization annealing was performed in wet hydrogen at 830°C, which also served as decarburization, and then MgO (2%), Al ₂ O ₃ (70
%), TiO ₂ (5%), ZrO ₂ (5%) annealing separators were applied, and after secondary recrystallization annealing at 850 °C for 50 hours,
Blunt annealing was performed at 1200° C. for 5 hours in dry H ₂ gas.
Thereafter, oxides on the surface of the steel plate were removed by light pickling, and then electrolytic polishing was performed to finish the surface of the steel plate to a mirror finish. After that, a thin TiN film was formed using PVD (ion plating equipment), and an insulating film containing phosphate and colloidal silica as main components was baked, followed by strain relief annealing at 800°C for 3 hours. I went. The magnetic properties of the product at that time depending on its plate thickness,
Table 2 shows the film thickness and magnetostriction compressive stress characteristics of the TiN thin film (values of magnetostriction λpp when compressive stress σ is 0.4 Kg/mm ² and 0.6 Kg/mm ² ).

[Table] (Effects of the Invention) The ultra-thin tension coating of the present invention significantly contributes to improving the magnetostrictive compressive stress characteristics as well as the magnetic properties of grain-oriented silicon steel sheets.

[Brief explanation of the drawing]

Figure 1 is a graph showing the magnetic properties and magnetostrictive compressive stress characteristics of a silicon steel sheet with an ultra-thin TiN tension coating and a silicon steel sheet made of a conventional process material (comparison material). Figure 2 shows the iron loss and magnetostrictive properties Good product thickness and TiN
It is a chart showing the relationship between thin film thickness.

Claims (1)

[Claims] 1 Consisting of an ultra-thin layer of at least one of TiN, TiC, and Ti(CN), it firmly adheres to the mirror surface of a finish-annealed unidirectional silicon steel plate with a centerline average roughness of 0.4 μm or less. An ultra-thin tensile coating that improves the compressive stress characteristics of magnetostriction on a grain-oriented silicon steel sheet.