JPS6289816A - Manufacture of electrical steel sheet having superior suitability to blanking - Google Patents

Abstract

PURPOSE:To stably obtain an electrical steel sheet having superior magnetic characteristics and satisfactory suitability to blanking by hot rolling and cold rolling a steel having a much higher C content than a conventional electrical steel sheet and by annealing the resulting steel sheet under specified conditions so as to precipitate graphite. CONSTITUTION:A steel consisting of, by weight, 0.1-1.0% C, <=3.5% Si, one or more among <=2.0% Ni, <=1.0% Al and <=1.0% Cu and the balance Fe is hot rolled and cold rolled. The resulting steel sheet is subjected to recrystallization annealing at 600-800 deg.C. By this annealing, a structure necessary for an electrical steel sheet is ensured and graphite is precipitated in the matrix of the steel sheet to improve the suitability to blanking and to prevent deterioration in the magnetic characteristics due to sol. C.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for manufacturing an electric wire having excellent magnetic properties and extremely good punchability.

Background technology Generally, electromagnetic steel sheets are used as iron core materials for various transformers, ballasts, and various electric motors. From this point of view, there is an increasing demand for high-performance electric bBm plates with even higher magnetic properties.

On the other hand, electric FIBm plates undergo a punching and laminating process when being formed into the iron core of an electric motor.
1a Not only is it required to have good feel, but it is also required to have good punching properties.

For this reason, conventionally, when punching and forming electrical steel sheets, the surface is coated with an organic component such as acrylic resin to ensure electrical insulation and provide lubricity for the punching process. However, when assembling electrical products, the edges of the laminated iron cores are sometimes welded to secure them, and in this case, 1 during one weld = organic components in the coating film. evaporates and tends to cause welding defects such as blowholes, which inevitably limits the coating film thickness.

For this reason, there has been a strong desire to develop a 1yLIiailIi board in which the material itself has excellent punchability.

By the way, as the punching work of magnetic steel sheets continues, the punching die wears out, and the clearance between the punch and die gradually decreases, causing the 1st edge of the punched product to deteriorate.
is increasing. For this reason.

When the value of the "burr" becomes larger than that, it becomes necessary to perform mold polishing. Therefore, in electromagnetic steel sheets, steel sheets that can be punched out more in one round of mold polishing are evaluated to have better edge punching properties.

That is, to improve the punching properties of the TLA board.

As seen in free-cutting steel, it is said to be effective to include large amounts of precipitates and inclusions to improve the breakability of the steel sheet during punching.

However, in order to improve the magnetic properties of electrical steel sheets, it is necessary to reduce impurity elements such as C as much as possible, as well as suppress precipitates and inclusions. There existed an extremely troublesome problem that the punching performance deteriorated.

Means for Solving the Problems> The present inventors have solved the above-mentioned problems in the production of the As a result of extensive research, the following findings were obtained.

(al) A steel containing a much larger amount of C than is commonly known in conventional electrical steel sheets is hot-rolled and cold-rolled according to the normal thin plate manufacturing process, and then annealed under specific conditions. Then, coarse graphite is precipitated in the base material of the sheet metal sheet, and this improves the tearability of the steel sheet, thereby significantly improving the punchability. Since the amount of molten C is extremely small and the precipitated graphite does not interfere with grain growth or movement of domain walls, the substrate is made of a ferrite structure containing elements such as Si and M that are effective in reducing overcurrent loss. If this is done, it is possible to obtain an electromagnetic steel sheet having magnetic properties comparable to those of conventional ultra-low C electromagnetic steel sheets.

This invention was made based on the above findings, and includes: C: 0.1 to 1.0% (hereinafter, % representing the component ratio is referred to as heavy %).

Sl: 3.5% or less contains, and Ni: 2.0% or less.

M: 1.0% or less.

A piece containing one or more of Cu: 1.0% or less and the remainder consisting of Fe and unavoidable impurities is hot-rolled and cold-rolled and then recrystallized and annealed at 600 to 800°C to precipitate graphite. By doing so, it is possible to obtain an electric 5!1wA board that has excellent punching and punching properties and magnetic properties.

It has the following characteristics.

Next, an explanation will be given of an egg white in which the composition of the steel material and the processing conditions are numerically limited to the above-mentioned QD < in the method of the present invention.

A. Composition of material steel a) C C is a component that precipitates as coarse graphite in a sheet by prescribed annealing and improves the punchability of the steel sheet.
If the content is less than 0.1%, it becomes difficult to precipitate coarse graphite, and a sufficient effect of improving punching performance cannot be secured.
On the other hand, if the content exceeds 1.0%, hot rolling becomes difficult, so the C content was set at 0.1 to 1.0%.

b) 5i Si is an effective component for improving the magnetic properties of electric 1iala plates and promoting the precipitation of graphite, but its content is 3.5%.
The pupil content of 81 was set at 3.5% or less, since the workability of the steel deteriorates if it exceeds 3.5%. Although Si has a certain effect even in a very small amount, it is preferably 0.1%.
It is better to secure companies that contain the above.

C) Ni + M, and Cu These components are also effective elements for promoting the precipitation of graphite, and even if added in a very small amount, they will have a corresponding effect, so one or more of these components can be included. 2.
Ni over 0%, M over 1.0%, and 1.0
Even if Cu is contained in excess of 2.0%, the effect of promoting graphite precipitation will not be significantly improved and it is economically unfavorable.
The Cu content was determined to be 0% or less, and the Cu content was determined to be 71.0% or less.

B. Recrystallization annealing deviation The recrystallization annealing practiced in the method of this invention has a magnetic (
IA-Not only to secure the necessary tissue for the plate, but also to
It is also intended to precipitate graphite in the base material of the plate to improve punchability and prevent the tendency of deterioration of magnetic properties due to solid solution Cl2, but if the annealing temperature is less than 600°C, sufficient If graphite is not used in combination, it becomes difficult to stably secure satisfactory air properties, and the same problem occurs even when the annealing temperature exceeds 800°C.
The recrystallization annealing temperature was set at 600 to 800°C.

In this way, in the case of the component system described in [11.
'C is the most effective, but it completely prevents graphite precipitation.
It is preferable to adjust the soaking time depending on the ingredients in order to achieve a high temperature.

Note that normal conditions are sufficient for the hot rolling and cold rolling that occur in the method of the present invention, and box annealing is preferably employed for recrystallization annealing.

Next, this invention will be compared with examples! ! This will be explained by comparing with two examples.

<Example> First, the first
After obtaining the +2 [] ljW composition slab shown in the table, it was hot rolled to form a 2.31 thick hot rolled coil, which was then pickled and then rolled by Reima Onobu. 0.5
- A thick cold-rolled coil.

Next, the above? The rolled cocoil was further subjected to recrystallization annealing which also served as graphite precipitation annealing, and the magnetic properties and punchability of the resulting electromagnetic sheet were measured.

The results obtained are shown in Table 3 together with the IILL conditions.

The punchability of electrical steel sheets is generally evaluated by measuring the number of punches until one burr becomes 50 μm, but this requires a large specimen.
Also, a lot of time is spent setting up and measuring molds.

However, when we measured the relationship between the punch stroke and the punching load position during one punching process as shown in Figure 1,
Comparing the results, it is clear that the punching performance of Den Fama is
The present inventors have discovered that t2 evaluation is possible.

That is, in FIG. 1, the shear stroke indicated by the arrow (Sl corresponds to the part where the material breaks in a shear manner due to its viscosity during punching, and the part h that appears as a shear fracture surface on the punching fracture surface) Therefore, materials such as #1, whose shearing stroke is smaller than the thickness of the plate, are punched brittle and have a small burr. By comparing the expressed shear stroke ratios, punching performance can be accurately evaluated.

Therefore, "punching property" is expressed here as "shearing stroke".

From the results shown in Table 2, it is clear that by processing steel with a composition that satisfies the conditions specified in the present invention according to the conditions specified in the present invention, it is possible to obtain an electrical steel sheet with excellent magnetic properties and punchability. That is clear.

Moreover, FIG. 2 shows #A produced by the method of the present invention.
Conventional steel with almost the same composition except for the plate and C-containing acid (ultra-low C steel)
Fig. 2 is a graph comparing the relationship between shear stroke ratio and shear strength for the steel plates manufactured by the method of the present invention. It can be seen that the ``burr'' during time is small and the wear of the die is also small, and the punching performance is significantly improved.
It is obvious at a glance that this is a rebellion. In addition, the actual punching +q+ number when the "burr" becomes 50 μm is, for example, 3. for Comparative Example 10. Whereas it was about 10,000 times,
Inventive Example 1 exceeded 400,000 cycles.

By the way, Fig. 3 is a microscopic photograph 7 showing the cross section of the electromagnetic wire manufactured by the method shown in Test No. ,
The reason for the improved punchability can be clearly explained. In addition, when we measured the solid solution of carbon in the base material of Konotona, we found that
It has been confirmed that the value is below 50 ppm.
Ta.

Overall effect> As described above, according to the present invention, it is possible to stably perform FJm of an electromagnetic sheet that not only has excellent magnetic properties but also has extremely good punching properties. This will bring about beneficial effects such as making it possible to

[Brief explanation of drawings]

Fig. 1 is a graph showing the relationship between punch stroke and load during punching of electric Fa steel m, Fig. 2 is a graph comparing shear strength and shear stroke ratio between the present invention material and conventional material. Figure 3 is a photograph of the microscopic structure of a cross-section of a sheet of electromagnetic copper according to the present invention, which was obtained from a leprosy case.

Claims (1)

[Claims] Contains C: 0.1 to 1.0% and Si: 3.5% or less in weight percentage,
The steel also contains one or more of the following: Ni: 2.0% or less, Al: 1.0% or less, Cu: 1.0% or less, and the balance is Fe and unavoidable impurities by hot rolling and cold rolling. A method for manufacturing an electrical steel sheet having both excellent punchability and magnetic properties, characterized by precipitating graphite by rolling the steel sheet and then recrystallizing it at 600 to 800°C.