JPS6319573B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method for manufacturing grain-oriented electrical steel sheets with extremely excellent magnetic properties, and more specifically, the iron loss is extremely low due to magnetic domain refining, which does not lose its iron loss improvement effect even after heat treatment. The present invention relates to a method for manufacturing grain-oriented electrical steel sheets with good magnetic flux density. [Prior Art] Grain-oriented electrical steel sheets are mainly used as iron core materials for transformers and other electrical equipment, so they need to have good excitation characteristics and iron loss characteristics. This steel sheet utilizes the secondary recrystallization phenomenon, and develops secondary recrystallized grains having a so-called Goss orientation, with a (110) plane on the rolling surface and a <001> axis in the rolling direction. By increasing the degree of integration of the (110) <001> orientation and reducing deviation from the rolling direction as much as possible, products with excellent excitation characteristics, iron loss characteristics, etc. are being manufactured. . By the way, as the degree of integration of the (110)<001> orientation increases, the crystal grains become larger, and the magnetic domain becomes larger because the domain wall penetrates the grain boundary, which is a phenomenon in which iron loss does not decrease as the degree of integration increases. There is. For example, Japanese Patent Publication No. 58-5968 discloses a technique for eliminating the above-mentioned phenomenon and reducing iron loss. This is done by pressing small balls etc. onto the surface of a unidirectional electrical steel sheet that has undergone final finish annealing to form depressions with a depth of 5μ or less and applying linear microstrain to subdivide the magnetic domains. , which improves iron loss. Also,
Japanese Patent Publication No. 58-26410 discloses that at least one mark is formed by laser irradiation on the surface of each crystal grain of secondary recrystallization generated by final finish annealing,
It has been proposed to subdivide magnetic domains to reduce iron loss. These Special Publication No. 58-5968 and Special Publication No. 58-
According to the method disclosed in No. 26410, iron loss is improved by applying local minute strain to the surface of a grain-oriented electrical steel sheet, and an ultra-low iron loss material can be obtained. [Problems to be Solved by the Invention] However, when the ultra-low iron loss material obtained as described above is annealed, the iron loss improvement effect is lost. There is a problem that the improvement effect disappears. The present invention efficiently performs magnetic domain refining that does not lose its iron loss improvement effect even when subjected to heat treatment, such as strain relief annealing, to achieve extremely low iron loss, good magnetic flux density, and good corrosion resistance and insulation properties. The purpose is to provide a method for stably manufacturing grain-oriented electrical steel sheets. Another object of the present invention is to produce a grain-oriented electrical steel sheet whose core loss does not deteriorate even when subjected to the strain relief annealing. The present inventors have developed a grain-oriented electrical steel sheet with extremely low iron loss by efficiently performing magnetic domain refining in which the iron loss improvement effect does not disappear even when subjected to heat treatment such as strain relief annealing at a temperature of 700 to 900°C after magnetic domain refining. In order to produce a product that does not cause rust and has excellent interlayer resistance with good productivity, we conducted experiments and investigated. [Means for solving the problem] Glass coating of finish annealed grain-oriented electrical steel sheet,
If surface coatings such as insulating coatings are removed at intervals, and the removed areas are plated with penetrants and bonded to the steel plate base, magnetic domain refining will not occur even if heat treatment such as strain relief annealing is subsequently performed. It has been found that the iron loss improvement effect caused by this method does not disappear, and grain-oriented electrical steel sheets with extremely low iron loss can be stably obtained. Next, an insulating coating solution containing one or more of phosphoric acid, phosphate, chromic acid, chromate, dichromate, and colloidal silica is applied to the steel plate and baked to form an insulating coating. This prevents the plated penetrable bodies from peeling off during subsequent work due to coil slipping, etc., or from dissipating during subsequent annealing, stabilizes the formation of the penetrants, and also provides good corrosion resistance and insulation properties. I discovered something. The decrease in iron loss due to the formation of intruders is caused by the presence of intruders with different steel composition or structure at intervals in a steel plate, which increases static magnetic energy, and in order to cancel this, reversal magnetic domains are generated. This is thought to be due to the subdivision of magnetic domains. The present invention has extremely low iron loss and excellent magnetic properties.
Furthermore, the present invention provides a method for stably and productively manufacturing grain-oriented electrical steel sheets with good corrosion resistance and insulation properties. The feature is that surface coatings such as glass coatings and insulation coatings of finish annealed grain-oriented electrical steel sheets are removed at intervals of 1 to 30 mm, and penetrants such as Sb, Cu, Sn, and Zn are removed from the steel sheets. , Cr, Mo, and
One or more alloys of any of these elements are plated with a basis weight of 0.05 g/m ² or more, then an insulation coating is applied, and if necessary, a coating weight of 700 to 900
The present invention provides a method for producing grain-oriented electrical steel sheets with extremely excellent magnetic properties, characterized by carrying out stress relief annealing at ℃. In the present invention, "penetrable body" refers to a substance that enters a steel plate by plating, and includes Sb, Cu, Sn,
Zn, Cr, Mo, and alloys of these elements. The term "invader body" refers to the state in which the intruder body is present in the steel plate in the form of grains, lumps, or lines in a state of being combined with steel plate components and the like. Heat-resistant magnetic domain refining according to the present invention can be performed as follows. That is, glass coatings, oxide coatings, etc. formed on finish annealed grain-oriented electrical steel sheets,
Surface coatings such as insulating coatings are removed at intervals by laser irradiation, grinding, cutting, melting, chemical polishing, pickling, corrosion, shot blasting, etc. to expose the steel sheet base, and then on the steel plate, When the penetrable human body is plated with a basis weight of 0.05 g/m ² or more by electroplating, melt plating, etc., the penetrable body is firmly bonded to the areas where the surface coating has been removed at intervals. Further, a part of the penetrant may form an alloy layer. That is, in finish annealing of a grain-oriented electrical steel sheet,
A glass film (forstellite film) formed by the reaction between the oxide film containing SiO ₂ formed in the decarburization annealing process in the previous process and the annealing separator whose main component is MgO.
The insulating film formed by applying phosphoric acid, aluminum phosphate, magnesium phosphate, chromic acid anhydride, colloidal silica, etc. to the steel plate and baking it can be used when plating penetrants on the steel plate. It has the effect of inhibiting that reaction. For this reason,
When the surface coating is removed at intervals to expose the steel plate base and plated, a reaction between the base metal and the penetrant material occurs selectively, and the steel plate is extremely firmly bonded to the steel plate. By controlling the area weight of the plating, the amount of bonding of the penetrable body with the steel plate can be easily changed, and the iron loss characteristic level can be differentiated. Also, the magnetic flux density can be changed depending on the basis weight. For example, if the basis weight increases, the magnetic flux density can be lowered while improving the core loss characteristics. Therefore, if the iron core of a transformer is manufactured using the steel plate, the actual iron loss will be greatly improved. Next, the steel plate is treated with phosphoric acid, phosphates such as aluminum phosphate, magnesium phosphate, zinc phosphate, and calcium phosphate, chromates such as chromic acid and magnesium chromate, dichloromate, and colloidal silica. An insulating coating solution containing one or more species is applied and baked at a temperature of 350°C or higher to form an insulating coating. This insulating coating treatment prevents the penetrable body bonded to the steel plate from peeling off due to friction or slips during coil winding, and also improves corrosion resistance and prevents rust from forming. . Furthermore, baking during this insulating coating also has the effect of causing penetrants to enter the steel plate. The present invention will be specifically explained below based on an example in which a penetrant is electroplated onto a finish annealed grain-oriented electrical steel sheet. In the present invention, finish annealed grain-oriented electrical steel sheet has
Although magnetic domain refining is performed, it is not necessary to specify the steel composition of the grain-oriented electrical steel sheet and the manufacturing conditions until final annealing.
Appropriate materials such as AlN, MnS, MnSe, BN, Cu ₂ S, etc. are used, and Cu, Sn, Cr, Ni,
Elements such as Mo and Sb are contained, and the slab is further hot-rolled and annealed once or twice after annealing.
There is also no need to specify the conditions of a series of processes in which the final plate thickness is obtained by cold rolling several times or more, decarburization annealing, application of an annealing separator, and finish annealing. By the way, a glass coating (forsterite coating) is formed on a finish annealed grain-oriented electrical steel sheet. This glass coating suppresses the reaction between the intrusive body to be electroplated in the application example of the present invention and the steel plate base metal, and the oxide film slightly present under the glass coating may also inhibit the above reaction. Further, if an insulating coating is formed, it has the same effect as the glass coating. To eliminate these harmful effects, the glass coating on the steel plate,
The oxide film, insulating film, etc. can be removed at intervals by laser irradiation, grinding, cutting, melting, local pickling, or the like. The spacing is 1 to 30 mm, and may be equidistant or irregular. The interval at which this surface film is removed is set to 1 mm or more, since the narrower the interval between the penetrants plated on the steel plate, the less the effect of subdividing the magnetic domains and the lowering of the magnetic flux density. On the other hand, if the interval is too wide, the interval between the platings of the penetrable body will become large, and in this case as well, the effect of subdividing the magnetic domain will be reduced, so it should be set to 30 mm or less. The direction of removal is preferably 30 to 90 degrees with respect to the rolling direction of the steel plate. Its removal is continuous,
It can be non-continuous. Also, the width of removal is 0.01
~5 mm is preferred for intruder formation. Removal of this surface coating exposes the steel plate base metal. This exposure also includes forming a slight dent in a part of the steel sheet base. Next, the penetrable body is electroplated onto the grain-oriented electrical steel sheet. If the surface coating is removed at intervals, the penetrants Sb, Sn, Zn, Cr, Mo and
One or more alloys of any of these elements, or oxides of the above elements, and if necessary, phosphates, borates, sulfates, nitrates, silicates, phosphoric acid, boric acid, etc. The steel plate is passed through an electrolytic solution to which is added and electroplated. During this plating, an electrical reaction occurs only at the locations where the surface coating is removed at intervals and the steel sheet base is exposed, and no such reaction occurs at other locations. Therefore, the penetrable body is plated only on the exposed portions of the steel plate base metal. In addition, since the part where the surface film exists does not react with the electrolyte as mentioned above,
Another effect is that the surface coating is maintained in a clean state. In this plating, the basis weight is important,
If the amount is small, the iron loss improvement effect will not occur. In order to achieve low core loss after stress relief annealing, a basis weight of 0.05 g/m ² or more (per area of the steel plate) is required. Next, an insulating coating liquid containing phosphoric acid, phosphate, phosphate and chromate, or phosphate, chromate and colloidal silica is applied to the steel plate,
Baking at a temperature of 350°C or higher forms an insulating film. Furthermore, when strain relief annealing is performed, the penetration of the intruder into the steel sheet is facilitated. This strain relief annealing is 700 to 900
Perform at a temperature of °C. If the strain relief annealing temperature is low, it will take a long time to eliminate the processing strain, so the temperature should be 700℃ or higher.
On the other hand, even if the temperature becomes higher, the effect hardly changes, so it is set at 900°C or less. FIG. 1 shows a micrograph (×1000) of an example of an intruder formed in a steel plate by applying the present invention. The composition of the invading body is different from that of the steel, and the structure is also different, so many buds of magnetic domains are formed on both sides of the intruder, and when the steel plate is magnetized, the buds of the magnetic domains extend,
It is inferred that the magnetic domains are subdivided. [Example] Examples will be described below. [Example 1] C: 0.081, Si: 3.22, Mn: 0.068, in weight%
A silicon steel slab consisting of Al: 0.030, S: 0.024, Cu: 0.13, Sn: 0.09, balance iron was hot rolled, annealed, and cold rolled by a well-known method to obtain a 0.225 mm thick steel plate. Next, the well-known steps of decarburization annealing--applying an annealing separator containing MgO as a main component--finish annealing were performed. The steel plate after finish annealing was used as the "before treatment" test material. The steel plate was irradiated with a CO ₂ laser to remove the glass coating and oxide coating at 5 mm intervals in a direction approximately perpendicular to the rolling direction, and then using an electrolytic solution containing the plating metal (penetrable body) shown in Table 1. , basis weight
Electroplated to 1.5g/ ^m2 , then applied an insulating coating solution containing aluminum phosphate, phosphoric acid, chromic anhydride, chromate, and colloidal silica and baked at 850℃ to form an insulating coating. This was used as the "after treatment" test material. As described above, the magnetic properties of each sample material "before treatment" and "after treatment" were measured. The measurement results are shown in Table 2.

【table】

[Example 2]

Weight%: C: 0.078, Si: 3.35, Mn: 0.068,
A silicon steel slag consisting of Al: 0.026, S: 0.024, Cu: 0.15, Sn: 0.08, and the balance iron was hot rolled, annealed, and cold rolled by a well-known method to obtain a 0.225 mm thick steel plate. Next, the well-known steps of decarburization annealing - application of an annealing separator containing MgO as a main component - and final annealing were carried out. The steel plate after final annealing was used as the "before treatment" test material. The steel plate was irradiated with a CO ₂ laser to remove the glass coating and oxide coating at 10 mm intervals in a direction approximately perpendicular to the rolling direction, and then using an electrolytic solution containing the plating metal (penetrable body) shown in Table 3. , basis weight 1
g/ ^m2 , then apply an insulating coating solution containing aluminum phosphate, phosphoric acid, chromic anhydride, chromate, and colloidal silica and bake at 850℃ to form an insulating coating. "After treatment"
This was used as the test material. After this, in order to remove the strain, strain relief annealing was performed at 800°C for 2 hours to obtain a "after strain relief annealing" test material. The above is "before treatment", "after treatment", and "after strain relief annealing"
The magnetic properties of each sample material were measured. The measurement results are shown in Table 4.

【table】

[Example 3]

Weight%: C: 0.080, Si: 3.30, Mn: 0.070,
Silicon steel slag consisting of Al: 0.028, S: 0.025, N: 0.0080, balance iron was hot rolled, annealed and cold rolled by a well-known method to obtain a steel plate with a thickness of 0.225 mm. Next, a well-known decarburization annealing process was performed, in which an annealing separator mainly composed of MgO was applied, and final annealing was performed. Thereafter, an insulating coating liquid was applied and baking was performed which also served as flattening annealing to form an insulating coating. This was used as the "before treatment" test material. This steel plate is irradiated with a CO ₂ laser to remove the glass coating and insulating coating at 5 mm intervals in a direction approximately perpendicular to the rolling direction, and then electrolyte solution containing penetrants shown in Table 5 is used to remove the coating weight from 0.05 to 10.0 g. /
Electroplated at ^m2 . Next, an insulating coating solution containing aluminum phosphate, chromic anhydride, chromate, and colloidal silica was applied, and an insulating coating was formed by baking at 350°C. This was used as the "after treatment" test material. Thereafter, strain relief annealing was performed at 800°C for 2 hours to obtain a "strain relief annealed" test material. The above is "before treatment", "after treatment", and "after strain relief annealing"
Table 6 shows the results of measuring the magnetic properties of each sample material. In addition, these samples were tested for time, interlayer resistance (JIS method 2), and corrosion resistance (constant temperature and humidity chamber test at 50°C).
x 24 hour humidity 98%). As a result, the interlayer current was zero in all cases, and no rust occurred.

【table】

〔Effect of the invention〕

As explained above, according to the present invention, the iron loss of the steel sheet is reduced by magnetic domain refining by the intruder, and even if strain relief annealing is subsequently performed at high temperature, the iron loss improvement effect is maintained. It has an excellent feature not seen in previous magnetic domain subdivision methods: it does not disappear.

[Brief explanation of the drawing]

FIG. 1 is a metal microscopic photograph (×1000) showing an intruder formed in a steel plate according to the present invention.

Claims (1)

[Claims] 1. Surface coatings such as glass coatings and insulating coatings of a finish annealed grain-oriented electrical steel sheet are removed at intervals of 1 to 30 mm, and Sb, Cu, Sn, Zn, Cr,
Mo, and an alloy of any of these elements
1. A method for producing grain-oriented electrical steel sheets with extremely excellent magnetic properties, which comprises plating one or more seeds with a basis weight of 0.05 g/m ² or more, and then subjecting them to an insulating coating. 2. Surface coatings such as glass coatings and insulating coatings of finish annealed grain-oriented electrical steel sheets are removed at intervals of 1 to 30 mm, and Sb, Cu, Sn, Zn, Cr,
Mo, and an alloy of any of these elements
The seed or two or more types are plated with a basis weight of 0.05 g/m ² or more, then subjected to insulation coating treatment, and then 700
A method for manufacturing grain-oriented electrical steel sheets with extremely excellent magnetic properties, characterized by carrying out strain relief annealing at ~900°C.