JPH0220710B2 - - 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 in recent years have been made 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 to open up 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 (011)[001], or Goss, orientation, and are mainly used in transformers and other electrical equipment. The magnetic flux density (B ₁₀
) is high, and iron loss (W _17/50
In addition to having a low value (represented by the value of This unidirectional silicon steel sheet is manufactured through a complex and diverse process, and has undergone numerous improvements over the years. Today, products with a thickness of 0.30 mm have magnetic properties such as _B10 value: 1.90T or more, W _17/50 value:
We also manufacture ultra-low iron loss unidirectional silicon steel sheets with magnetic properties of 1.05w/Kg or less, and magnetic properties of _B10 value: 1.89T or more and W17 _/50 value: 0.90w/Kg or less for products with a thickness of 0.23mm. It is becoming more and more common. Thus, at the excellent B ₁₀ and W _17/50 levels, ultra-thin tensile coatings useful for improving the magnetostrictive compressive stress properties of unidirectional silicon steel sheets have been developed as described below in order. This invention has led to a new investigation. 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 remarkable. In general, grain-oriented silicon steel sheets undergo annealing separation mainly consisting of iron oxide called fireite (Fe ₂ SiO ₄ ) and MgO, which are formed on the steel sheet surface during decarburization and primary recrystallization annealing before secondary recrystallization. Tension is applied by a forsterite undercoating produced by a high-temperature reaction during final annealing with the agent, and a double coating consisting of phosphate and colloidal silica on top of the forsterite base coating, 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) Insulating coatings that can apply elastic tension to the surface of steel sheets have been developed in order to improve magnetostrictive properties (see, for example, Japanese Patent Publication No. 56-521117 or Japanese Patent Publication No. 53-28375). It still lacks effectiveness. (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 practically possible to improve electrical and magnetic properties, and the following borides,
A thin layer of silicide, phosphide, and sulfide is coated on the surface of the unidirectional silicon steel sheet under strong adhesion to improve the magnetostrictive compressive properties while reducing iron loss. It is derived from new knowledge of what is possible. (Means for Solving the Problems) This invention removes non-metallic substances on the surface of a finish-annealed unidirectional silicon steel sheet, and then polishes the surface to make it smooth. At least one selected from the group consisting of borides of Ta, Al, Zr, Hf, V and W, silicides of Mo, W, Ti, Zr and V, phosphides of B and Si, and sulfides of Fe and Zn. An ultra-thin layer made of one type of metal and firmly adhered to the surface of the steel plate through a mixed phase with the base iron, and an insulating coated and baked layer that is superimposed and adhered on the ultra-thin layer. This is a unidirectional silicon steel sheet with excellent magnetic properties, especially magnetostrictive compressive stress properties. The explanation will begin with the experimental history that led to the success of this invention. C: 0.043% by weight (hereinafter simply expressed as %), Si:
3.36%, Mn: 0.062%, Se: 0.021%, Sb: 0.025
%, Mo: 0.025% was heated at 1360°C for 4 hours and then hot-rolled to form a hot-rolled sheet with a thickness of 2.4 mm. 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 plate with a thickness of 0.23 mm. Then decarburized in wet hydrogen at 820℃. After primary recrystallization annealing, Al ₂ O ₃ (70%) and MgO are added to the surface of the steel sheet.
(30%) was applied as a main component, followed by secondary recrystallization annealing at 850°C for 50 hours and purification annealing at 1200°C in dry hydrogen for 5 hours. After that, the steel plate surface was first pickled in HCl solution at 70℃ to remove oxides on the steel plate surface, and then chemically polished in a solution of 3% HF and H ₂ O ₂ to improve the center line average roughness of the steel plate surface.
Finished with a mirror finish of 0.05μm. Thereafter, using a CVD device, a 0.8 μm thick TiB ₂ tension thin film was formed by a CVD reaction on the steel plate surface for 15 hours at 850°C in a mixed gas atmosphere of TiCl ₄ , H ₂ , and BCl ₃ . Thereafter, an insulating film mainly composed of phosphate and colloidal silica 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). In this case, the comparison material was a part of the final cold-rolled sheet with a thickness of 0.23 mm, which was subjected to decarburization and primary recrystallization annealing in wet hydrogen at 820°C, and then MgO
In addition to applying an annealing separator mainly composed of The same procedure as for the above-mentioned sample material was used for baking the insulating film mainly composed of phosphate and colloidal silica, which was superimposed on the formed forsterite base film. As is clear from Figure 1, the magnetic properties of the product coated with the TiB ₂ ultra-thin tensile coating of this invention have a _B10 value.
1.925T, W _17/50 value is extremely good at 0.73W/Kg, and magnetostriction λpp is low at compressive stress of 0.4Kg/ ^mm2.
is 0.20×10 ⁻⁶ , and even if the compressive stress is increased to 0.6 Kg/mm ^{2 ,} the magnetostriction λpp is 0.65×10 ⁻⁶ , and the increase in magnetostriction is extremely small. On the other hand, the magnetic properties of products made from conventional process materials (comparison materials) have a B ₁₀ value of 1.90T and a W _17/50 value of 0.87W/
Kg, when compressive stress is applied, the magnetostriction λpp increases significantly, and for example, when the compressive stress σ is 0.4 Kg/mm ² , the magnetostriction λpp shows a large value such as 3.2×10 ^-6 . Subsequently, the inventors conducted extensive experiments to determine whether an ultra-low iron loss unidirectional silicon steel sheet having excellent magnetostrictive compressive stress characteristics as described above could be obtained even when the product sheet thickness was different. That is, C: 0.042%, Si: 3.38
%, Mn: 0.062%, Se: 0.021%, Sb: 0.025%,
Continuously cast silicon steel slab containing Mo: 0.025%
After heating at 1360° C. for 5 hours, hot rolling was performed to obtain a hot rolled sheet having a thickness of 1.8 to 3.0 mm. After that, hot-rolled sheets with different thicknesses were heated to 900℃ for 3
After homogenization annealing for 3 minutes, cold rolling was performed twice at 950℃ with 3 minutes of intermediate annealing in between.
The final cold-rolled sheets were obtained by grouping into 0.27, 0.30, and 0.35 mm thicknesses. 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 separator mainly composed of MgO (30%) was applied, followed by secondary recrystallization annealing at 850°C for 50 hours and purification annealing at 1200°C in dry hydrogen for 5 hours. After that, the steel plate surface was first pickled in HCl solution at 70℃ to remove oxides on the steel plate surface, and then chemically polished in a solution of 3% HF and H ₂ O ₂ to improve the center line average roughness of the steel plate surface.
Finished with a mirror finish of 0.05μm. Then, using a PVD (ion plating) device, ultrathin TiSi tensile films with various thicknesses ranging from 0.05 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 annealed at 800°C for 2 hours to remove strain, resulting in a product with magnetostrictive compressive stress characteristics. The results of measurements of magnetic properties 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 0.6×10 ^-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 TiSi film thickness, and it is necessary to reduce the TiSi film thickness for products with thin product board thickness, and to increase the TiSi film thickness for products with thick product board thickness. (Function) The reason why the magnetostrictive compressive stress characteristics and magnetic properties are improved by the formation of an ultra-thin tension coating after mirror polishing of a finish annealed unidirectional silicon steel sheet as described above, TiB ₂ or TiB 2, which has excellent adhesion to the steel plate,
This is thought to be due to the strong elastic tension given to the steel plate by forming the TiSi tension film. In addition, there is an optimum film thickness for TiB ₂ or TiSi tension coating depending on the thickness of the product.
It is necessary to increase the tension by increasing the thickness of the TiB ₂ or TiSi film. The tensile stress applied to silicon steel sheets in this way is effective not only for improving magnetostriction but also for improving core loss, and this effect is especially effective in the case of unidirectional silicon steel sheets with real magnetic flux density strongly concentrated in the Goss orientation. is remarkable. Next, a unidirectional silicon steel sheet and its manufacturing process according to the present invention will be explained. The starting materials are conventionally known unidirectional silicon steel sheet material components, such as C: 0.01-0.06%, Si: 2.0-4.0%, Mn: 0.01-0.2%, Mo: 0.003-0.1%, Sb: 0.005-0.2 %, one or two of S or Se
Composition containing 0.005-0.05% in total of species C: 0.01-0.06%, Si: 2.0-4.0%, Mn: 0.01-0.2%, N: 0.001-0.01%, Al: 0.005-0.06%, Sn: 0.01 ~0.5%, Cu: 0.01~0.3%, Mn: 0.01~0.2%, 0.005~0.05% in total of one or both of S or Se
Composition containing C: 0.01 to 0.06%, Si: 2.0 to 4.0%, B: 0.0003 to 0.02%, N: 0.001 to 0.01%, Mn: 0.01 to 0.2%, one or two of S or Se in total Composition containing 0.005 to 0.05% C: 0.01 to 0.06%, Si: 2.0 to 4.0%, Mn: 0.01 to 0.2%, Sb: 0.005 to 0.2%, 0.005 to 0.05 in total of one or both of S or Se %
It is applicable to compositions containing C: 0.01 to 0.06%, Si: 2.0 to 4.0%, Mn: 0.01 to 0.2%, and compositions containing one or both of S or Se in a total of 0.005 to 0.05%. be. Next, the hot-rolled sheet is either uniformly annealed at 800-1100°C and then cold-rolled once to achieve the final thickness, or it is usually subjected to intermediate annealing at 850-1050°C and further processed. In the two-step cold rolling method, in the latter case, the initial rolling reduction is about 50% to 80%, and the final rolling reduction is 50%.
The final cold-rolled plate thickness is 0.15mm to 0.35mm at a rate of 85% to 85%. After final cold rolling, the steel plate finished to the product thickness is surface degreased 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 or TiO ₂ was added 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 was conventionally impossible to form after finishing annealing, in order to simplify the subsequent mirror finishing of the steel sheet, so Al ₂ O ₃ , ZrO ₂ , TiO ₂ are used as annealing separators. etc.
It is preferable to use 50% or more of MgO mixed with MgO. After that, secondary recrystallization annealing is performed, but this step is carried out to sufficiently develop secondary recrystallized grains with {100}<001> orientation, and the temperature is usually raised to 1000℃ or higher immediately by box annealing. This is done by holding the temperature at that temperature. In this case, in order to develop a highly aligned secondary recrystallized grain structure in the {100}<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. Purification annealing after secondary recrystallization annealing is performed in dry hydrogen.
It is necessary to perform annealing at 1100°C or higher for 1 to 20 hours to achieve purification of the steel plate. After this purification 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 hub polishing, 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.
Finish as below. After such mirror polishing, Si, Nb, Ta, Al, Zr, Hf, V, and W are polished by CVD, ion plating, or ion implantation in the same manner as in the case of TiB ₂ and TiSi. By forming an ultra-thin tension coating consisting of at least one selected from borides, silicides of Mo, W, Zr, and V, phosphides of B and Si or sulfides of Fe, and sulfides of Zn. , the same effect is brought about. In this case, the optimum film thickness of each tension coating is also determined by the TiSi
As in the case of , it differs depending on the product board thickness, and for products with a thick product board, the film thickness is thicker, and for products with a thin product board thickness, the film thickness is thinner. An insulating film containing phosphate and colloidal silica as main components is baked onto the tension film produced as described above, and then strain relief annealing is performed at a temperature range of 600 to 900°C to produce a product. (Example) (Example 1) C: 0.055%, Si: 3.19%, Mn: 0.069%, Al:
0.026%, S: 0.026%, Cu: 0.09%, Sn: 0.07%
The unidirectional silicon steel containing the following was heated at 1460° C. for 3 hours and then hot rolled into a 2.0 mm thick hot rolled sheet. Thereafter, it was homogenized annealed at 1050°C for 3 minutes and then rapidly cooled. After that, it was subjected to temperature rolling at 300°C to obtain a final cold-rolled plate with a thickness of 0.20. After that, primary recrystallization annealing was performed in wet hydrogen at 840°C, which also served as decarburization, and Al ₂ O ₃ (60%), MgO (35
%), TiO ₂ (2%), and ZrO ₂ (3%) annealing separators were applied, the temperature was raised from 850°C to 8°C/hr for secondary recrystallization, and then at 1200°C for 8 hours. Purification annealing was performed in _H2 gas. Thereafter, oxides were removed from the surface of the steel plate by pickling, and then electrolytic polishing was performed to finish the surface of the steel plate to a mirror finish. Thereafter, using a CVD device, a 1.0 μm thick TiB ₂ tension film was formed by a CVD reaction on the steel plate surface at 880°C for 15 hours in a mixed gas atmosphere of TiCl ₄ , H ₂ , and BCl ₃ . The results of measuring the magnetostrictive compressive stress characteristics and magnetic characteristics of the product at that time were as follows. Magnetostriction λpp of product at compressive stress of 0.4Kg/ ^mm2 : 0.5
×0 ^-6 or less, magnetic properties B ₁₀ : 1.94T, W _17/50 : 0.71W/Kg (Example 2) C: 0.043%, Si: 3.37%, Mn: 0.063%,
A hot rolled sheet containing Mo: 0.025%, Se: 0.022%, and Sb: 0.025% was prepared. This hot-rolled sheet was uniformly annealed at 900℃ for 3 minutes,
Cold rolling was performed twice with intermediate annealing at 950° C. to obtain a final cold rolled sheet with a thickness of 0.23 mm. After decarburization annealing in wet hydrogen at 820℃, an annealing separator containing Al ₂ O ₃ (75%), MgO (20%), and ZrO ₂ (5%) as main components was applied to the surface of the steel sheet. 50℃
Secondary recrystallization annealing for 1 hour and 8 hours at 1200℃
Purification annealing was performed in _H2 . Thereafter, the oxide film on the surface of the steel plate was removed by pickling, and then chemically polished in a 3% HF and H _{2 O} solution to give a mirror finish. After that, thin films of various compounds were formed by CVD (no mark in Table 1), ion plating (○ mark in Table 1), and ion implantation (△ mark in Table 1), each with a thickness of 0.7 to 0.9 μm. I let it happen. 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. The magnetic properties and magnetostrictive compressive stress properties of the product at that time (magnetostrictive values λpp when the compressive stress σ is 0.4 and 0.6 Kg/mm ² ) are summarized in Table 1.

【table】

[Table] (Example 3) C: 0.056%, Si: 3.29%, Mn: 0.078%, Al:
A unidirectional silicon steel sheet containing 0.025%, S: 0.030%, Cu: 0.1%, and Sn: 0.05% is heated at 1440°C for 5 hours and then hot rolled to produce a hot rolled sheet with a thickness of 1.6 to 2.7 mm. And so. Thereafter, it was homogenized annealed at 1100°C for 3 minutes and then rapidly cooled. Thereafter, warm rolling was performed at 350°C to produce final cold-rolled sheets with thicknesses of 0.20, 0.23, 0.27, and 0.30 mm. After that, primary recrystallization annealing was performed in wet hydrogen at 850°C, which also served as decarburization, and then Al ₂ O ₃ (70%), MgO (20
%), TiO ₂ (5%), and ZrO ² (5%) annealing separators, and after secondary recrystallization annealing at 850℃ for 50 hours,
Purification annealing was performed at 1200°C for 5 hours in dry Hz gas. Thereafter, oxides on the surface of the steel plate were removed by pickling, and then electrolytic polishing was performed to finish the surface of the steel plate to a mirror finish. After that, a thin ZrSi 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. At that time, the product's magnetic properties by plate thickness, ZrSi thin film thickness, and compressive stress properties of magnetostriction (compressive stress σ
The values of magnetostriction λpp at 0.4 Kg/mm ² and 0.6 Kg/mm ² are shown in Table 2.

[Table] (Effects of the Invention) The present invention is useful as a unidirectional silicon steel sheet, as the magnetic properties are significantly improved, especially including the magnetostrictive compressive stress properties.

[Brief explanation of drawings]

Figure 1 is a graph showing the magnetic properties and compressive stress characteristics of magnetostriction of a silicon steel plate with a TiB ₂ ultra-thin tension coating and a silicon steel plate of a conventional process material (comparison material). Figure 2 is a graph showing iron loss and magnetostriction properties. Good product thickness and TiSi
It is a chart showing the relationship between thin film thicknesses.

Claims (1)

[Claims] 1. After removing non-metallic substances on the surface of a finish-annealed unidirectional silicon steel sheet, Si, Ti, Nb, Ta, Al, Zr, Hf are applied to the polished and smooth surface. , borides of V and W, silicides of Mo, W, Ti, Zr and V, phosphides of B and Si, and sulfides of Fe and Zn; A unidirectional silicon steel sheet with excellent magnetic properties characterized by having an ultra-thin layer firmly adhered to the surface of the steel sheet through a mixed phase with base iron. 2 After removing the non-metallic substances on the surface of the finish-annealed unidirectional silicon steel sheet, Si, Ti, Nb, Ta, Al, Zr, Hf, V and W are applied to the polished and smooth surface. oxide, silicides of Mo, W, Ti, Zr and V, phosphides of B and Si, and sulfides of Fe and Zn, and a mixed phase of these with base iron. A unidirectional magnetic material with excellent magnetic properties, characterized by comprising an ultra-thin layer firmly adhered to the surface of a steel plate through a wafer, and an insulating coated baking layer overlaid on the ultra-thin layer. silicon steel plate.