JPS5845352A - Semi-processed electrical steel plate with superior punchability and its manufacture - Google Patents

Abstract

PURPOSE:To enhance the punchability of a semi-processed electrical steel plate contg. specified amounts of Si, Al, Mn, C and P by precipitating and dispersing fine carbide in the crystal grains of the plate at a specified average distance or below before punching the plate and by regulating the Vickers hardness to a specified value or above. CONSTITUTION:A semi-processed electrical steel plate is composed of, by weight, <1% Si, <0.5% Al, 0.1-0.5% Mn, 0.02-0.05% C, <0.1% P and the balance Fe, and before punching the plate, fine carbide is precipitated and dispersed in the crystal grains of the plate at <=0.4mum average distance. The Vickers hardness is regulated to >=130. The plate is subjected to strain relief annealing after punching. The annealing is carried out at 720 deg.C for about 2hr.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a Naniso P-7 electrical steel sheet with excellent punchability and a method for manufacturing the same. The present invention relates to an excellent cold-rolled non-oriented semi-processed electrical steel sheet and its manufacturing method.

Non-oriented electrical steel sheets are often used by punching, but those with a lower 81 content than grain-oriented electrical steel sheets are often used, and in this case, the hardness is low and the material is soft. ,
Since the punchability is poor, improvements in the punchability have conventionally been attempted mainly by applying an insulating coating treatment or work hardening treatment.

By the way, in low-silicon steel sheets and pure iron electromagnetic steel sheets, due to their softness, force curvature is likely to occur during punching. In addition, plates with this force burr cannot be laminated as they are, so a process called burr removal is usually performed to remove the force burr, but if the material is soft, the force burr will sag, making it difficult to remove the burr. It is. Vickers hardness is 100
In the following cases, punching performance is significantly deteriorated due to this problem, but if the Vickers hardness is 130 or more, force curvature is less likely to occur, and even if force curvature occurs, it is easy to remove burrs.

Conventionally, in order to produce an electromagnetic steel sheet with a Vickers hardness of 730 or higher and good punchability, the hot-rolled sheet is cooled, then annealed, and then subjected to light cold rolling of less than 10% before being shipped.

In this case, due to the light rolling of the third round, work hardening occurs and the hardness increases, so that a product with good punchability can be obtained. but,
Cold-rolling the second round also increases costs, and the strain stress introduced by the second light rolling is released by annealing after punching, but at this time the shape of the plate often deforms. . This is presumed to be because the way in which strain is introduced by rolling is not uniform, and there are differences in the thickness direction and sheet surface direction.

For example, when a plate punched into a perfect circle is annealed, it may become elliptical or warped. For this reason, troubles occur during assembly in the post-process. Therefore, in consideration of cost and deformation during annealing after punching, it is still difficult to say that this is a satisfactory product.

Furthermore, a method is conventionally known in which organic matter is mixed into the insulating coating to improve punching properties, but this method involves a large cost increase due to the mixing of organic matter. Furthermore, although the punching performance is improved, the material is inherently soft, so once a force burr has occurred, it is difficult to remove the burr, as described above.

The purpose of the present invention is to provide a semi-processed electrical steel sheet that eliminates the above-mentioned drawbacks of conventional semi-processed porcelain copper sheets and has improved ti-9 and excellent drawability, and a method for manufacturing the same. The above object can be achieved by providing an electromagnetic steel sheet and a method for manufacturing the same as described in the claims. That is, the present invention provides Vickers hard fil 130
The present invention aims to provide a semi-processed electrical steel sheet with excellent punchability and a method for manufacturing the same.

Next, the present invention will be explained in detail.

The present inventors have newly discovered that the hardness of the material can be controlled by controlling the precipitation state of fine carbides in the electrical steel sheet, and have completed the present invention.

There are two types of electrical steel sheets: full-produced steel sheets that are used as they are after being punched, and semi-processed steel sheets that are used after being subjected to a predetermined annealing process after being punched. 81 companies containing 7% or less,
When used as a semi-processed steel plate, the Vickers hardness after annealing is /30 or less, resulting in poor punchability.
It is used after cold rolling, punching, and strain relief annealing. However, as mentioned above, this results in high costs and deformation during annealing after punching, so it is desirable to produce semi-processed steel sheets as they are annealed after cold rolling. We have found a method to increase the Vickers hardness to 130 or higher and improve punchability without impairing the properties of Nichiden Pro-Nanas electrical steel sheets. It is known that hardness increases when carbides are finely dispersed and precipitated in a structure. However, in electromagnetic steel sheets, C significantly impairs the electromagnetic properties, and during use as electrical equipment, causes magnetic aging and deteriorates the properties, so it is common to keep the zero content as low as possible.

Incidentally, semi-processed steel sheets are subjected to strain relief annealing after punching, but this annealing is usually at 30° C. for about one hour, and decarburization also progresses at the same time. Is the zero content after this annealing 0.0? ) It is known that the influence of deterioration of electromagnetic characteristics due to 1G does not pose a practical problem if it is 1% or less.

Next, the present invention will be explained using an experimental bag.

0.4 of various ingredients! DI gas composition H2 oligo/Co-arc commonly used in strain relief annealing of t-thick specimens.

00:t%e C02:! r% - dew point 7℃,
Annealing was performed at a temperature of 710°C for 2 hours in residual Ng. Table 1 shows the O analysis values before and after annealing in this case.

Table 1 From Table 1, is the material 0 equal to 0.0? It's your turn to be below %! .

It can be seen that by strain relief annealing after punching, decarburization can be achieved to 0.00 or less, which is a practically acceptable O content.

This section describes the results of tests regarding freezing hardness.

Sl t o, oa attack t O: 0.0!
%-M Tsukasa: 0. Koji Attack TM110.01
A hot rolled sheet of - was annealed in the air, and the annealing time was varied to reduce the amount of 0% of the sample to 0.001% e O, 0/% (
analysis value 0.0ll%), 0.0ko arc (analysis value 0.0ll%)
-0%) -0,03% (Analysis value 0.0J day) Meeting o,
Adjust to oti% (analytical value o, o4Ii≦), and after pickling Q
After cold rolling to a thickness of 0gml and annealing at 770℃ for 1 minute using normal continuous annealing, the cooling rate was reduced to 00''Q.
/mix v 100℃/wa 1n + 400”C
/! Elin * EOO℃/win t 1
00θ'(/mix t coooo℃/ml i
n p3000℃l/wrL* e! 000℃/mi
x and cooled to room temperature. The Vickers hardness after cooling is below 1JO, and the punching properties are poor as is. Next, all the samples were subjected to aging precipitation treatment at 110°C for 1 minute, and as shown in Figure 7, the 0 content was 0.0 core arc or more, and the cooling rate was too°C/min or more. It has been found that a value of Vickers hardness greater than ISO can be obtained in the case of .

Next, when the aged sample was observed with an electron microscope (X 10,000), it was found that many fine carbides were precipitated in the sample with high hardness, as shown in Figure 1.

Therefore, the relationship between the average distance of the amount of precipitates and Bitkars Ii was investigated. According to this, as shown in Figure 3, if the average distance of precipitates is 0.3 pva or less, the Vickers hardness is 13
It was found that it is certain that the value is 0 or more.

The reason why a high cooling rate has an effect on age hardening is that the rapid cooling increases the amount of supersaturated solid solution O, and the aging treatment increases the amount of fine carbides that form within the grains. I understand.

Next, using one of the aforementioned samples in which the amount of C was adjusted to 0.0, after pickling, it was cold rolled to a length of 1 m, and after annealing for 1 minute at t7O ℃ by normal continuous annealing, Cooling rate Oθ”C
/win and cooled to room temperature. Next, an aging treatment was performed at a temperature of 10 seconds to 1 hour and 30 minutes at a temperature of 100°C to 300°C, and the hardness of each product was examined. 0-ko! Between θ℃, lO~/lOs
It was found that a Vickers hardness/JO or higher can be obtained up to ea, and that the hardness increases by holding for more than 1 minute at around 700°C, and a Vickers hardness of 130 or higher can be obtained.

Therefore, among the samples mentioned above, the amount of 0 was adjusted to 0.0 da%, and after pickling, the amount of 0 was adjusted to 0.0%. ! - After cold rolling and annealing for 1 minute at θ℃ by normal continuous annealing, the cooling rate was changed to 70θ℃/E.
The mixture was taken in a lint and cooled to room temperature. Next, using a tensilon leveler, the strain amount O1θ, ko, o, z, 1.0
External processing was applied. Calculation of the amount of distortion is (j-Jo)+
１６
0g@6 annealed and the influence of repeller processing was investigated.

The results are shown in Table 1. As seen in the same table, it was found that the hardness increased by applying the repeller process, and the effect of imparting strain was recognized.

Table 1 Next, the reasons for limiting the components of the present invention will be described.

When the Si content exceeds 1%, it is relatively easy to obtain a Vickers hardness of /30 or more, so the Si content is targeted to be 1% or less. Aj is an element that improves electromagnetic properties, but in this class it is usually less than 0.5%, so A) is O, S
% or less. In order to improve hot brittleness, Mu is added in an amount of 0.7% or more, or if it exceeds θ,j%, age hardening becomes difficult to occur, so C is limited to a range of 0.1 to O,S%. Since it is difficult to obtain a hardness of 130 or more unless 0 is 0.01% or more, it is set to 0.0-1 or more, but o, or
If it exceeds 0.0%, as mentioned above, decarburization will occur during strain relief annealing after punching and the magnetic properties will be impaired. θko~O,O
Limited within the range of S%. P is an element that increases hardness, but since it exists in a solid solution state, it does not make a large contribution to increasing hardness. However, if it exceeds O6/-, cold workability is impaired, so P is limited to 0.7% or less. Next, the reason for limiting the manufacturing conditions of the present invention will be described. In order to effectively cause age hardening, the cooling rate must be at least 60θ'' (/min) as shown in Figure 1. However, for temperatures below 300°C, as shown in Figure 4I So, 150-cog.

Since it is necessary to maintain 'Cte10~/lOsea, after cooling to 0℃, it may be cooled slowly at a cooling rate of less than lθθ''C/rnin, or once cooled to a constant temperature of less than yoo''C. and then again at iso~coso℃ for 10~lt
Aging processing may be performed between Oseas. In addition, at this time, the aging treatment at /5O-130°C is performed at 750-80°C.
The same effect can be obtained even if the coating is replaced with a coating baking heat treatment of 0 to /lOsea.

As can be seen from Figure 9, the hardness increases from 200℃ to around /θO℃ even if the temperature is slowly cooled over a long period of time.
A coil cooled at a rate of wm i m or more is heated to J00℃
Slow cooling may be performed at a temperature between ~10° C. by utilizing the self-heat retention of the wound coil. If the coiling temperature was less than t0°C, age hardening would take too long and would be impractical, so it was excluded. After coil winding, it is advantageous to attach a heat insulating cover to a small weight coil or a low temperature coil in order to control the cooling rate of the coil. Conventionally, it has been said that the lower the coil winding temperature is, the better, in order to suppress the occurrence of temper color, and the coil winding temperature is usually below tO 0 C, and the above-mentioned measures according to the present invention have not been taken.

As shown in Table 1, introducing a slight strain between the rapid solid solution treatment and the precipitation aging treatment is effective in increasing the hardness of the material. As means for adding this strain, there are bending processing using a leveler, tension processing using tension rolls, and skin bath processing using rolling rolls.
The point is that it is sufficient to introduce the necessary strain, and any of these three methods or a combination of these methods may be used. The evaluation of the amount of distortion is (to-t) + tox to/ (
%). However, no and to are the length and thickness of the sample before processing, and J and t are the length and thickness of the sample after processing.

If this amount of strain exceeds 0.1%, it is not preferable because it will result in a shape defect during strain relief annealing as described above after punching the material, so the amount of strain to be added is limited to 0.03% or less.

As shown in Table 1, it is advantageous to add strain in order to increase hardness, but it increases cost, so depending on the price of the material and the punching characteristics, it is better to add strain. Just choose.

Next, the present invention will be explained with reference to examples and comparative examples.

Example! Table 3 A hot-rolled sheet with a thickness of 2 and having a composition of the sample symbol Mut B * Oe D shown in Table 3 was pickled and cold-rolled once to a final thickness of Q, j; 1111, 7 "Continuously annealed for 3 minutes in a dry hydrogen atmosphere at 0℃, de00"C/
! Cooling at a cold tlit rate of ll1n, followed by
from/! It was cooled between 0"C at a rate of SOo (/l11in).

Comparison column! A hot-rolled sheet having a thickness of J- and having a composition of F, G, and H according to the sample numbers shown in Table 3 was pickled, and the same treatment as in Example 1 was performed after cold rolling.

Comparative Example A hot-rolled sheet having a composition of sample code M-BtotD shown in Table 3 and having a thickness of °C was pickled and cold-rolled once to a final thickness of OJ.
- and then continuously annealed for 2 minutes in a dry hydrogen atmosphere at 0°C, and cooled to 100°C at a cooling rate of JOO°C/win.

A hot-rolled sheet with a thickness of 1 cm and having the composition of the sample code M, B, O, and D shown in Example No. J was pickled, and the final thickness was 0.3 by one cold rolling.
-, then continuously annealed for 3 minutes in a dry hydrogen atmosphere at 0°C, cooled to 300°C at a cooling rate of 0θ°C/m1!1, and then subjected to skin pass rolling of 0.3≦ at a temperature of -50°C. and immediately return it to the heat retention furnace (set at 0°C).
It was cooled from 0°C to 730°C at a rate of so°C/mum.

Example I A factory hot-rolled coil with a thickness of 1 cm and having the same composition as the sample code Beo shown in Table 3 was subjected to a pickling process and a cold rolling process to a final thickness of 7. j After being made into W, continuous annealing was performed. The conditions for continuous annealing were as follows: After passing the plate for 3 minutes in a dry nitrogen atmosphere at trzo"c, cooling to 6θ°C at a cooling rate of 900°C/win, and then annealing at a temperature of Joo"c for 1 minute in the aging zone. The statute of limitations was applied.

Example ■ A factory hot-rolled coil with the same composition as sample code Be (3) shown in Table 3 and having a thickness of 2 strips was subjected to a pickling process and a cold rolling process to a final thickness of O, S■, and then continuously rolled. It was annealed in an annealing furnace.The conditions for continuous annealing were as follows: After passing the plate for 1 minute in a dry nitrogen atmosphere of tzo"c, the temperature was 6θ°C at a cooling rate of 900°C/wim.
After cooling to a temperature of 0° C., a strain of o and r% was applied to a part of the louver, and then aging treatment was performed at a temperature of 0° C. for 1 minute in an aging zone.

Example ■ A factory hot-rolled film having the same composition as the sample symbols B and O shown in Table 3 and having a thickness of 100 mm was subjected to a pickling process and a cold rolling process to a final thickness of O and S-, and then continuously rolled. Annealed. The conditions for continuous annealing were as follows: in a dry nitrogen atmosphere, the plate was passed for a minute at τ00″C, then rapidly cooled at a cooling rate of 00°C/win, and then heated to 100°C.
Example V The coil was wound at a temperature of Thickness 0. After it was made into j ss, it was annealed in a continuous annealing furnace.

The conditions for continuous annealing were as follows: in a dry nitrogen atmosphere, the plate was passed for 1 minute at 00°C, then rapidly cooled at a cooling rate of 00°C/win, and after adding a strain of 0.3 arc to a part of the louver, The coil was wound at a temperature of °C.

A factory hot-rolled coil with a thickness of 1 mm and having the same composition as sample numbers B and O shown in Table 3 was subjected to a washing process and a cold rolling process to a final thickness of 0. j 1111 and annealed in a continuous annealing furnace,
Coating baking treatment was applied. The conditions for continuous annealing were as follows: in a dry nitrogen chamber, after passing the plate for 3 minutes at toθ℃, at de00℃/
It was cooled at a cooling rate of 1. The five conditions for the coating baking treatment were a board temperature of -00°C for 1 minute.

Example ■ A factory hot-rolled coil of one thickness having the same composition as the sample code B-C shown in Table 3 was subjected to a pickling process and a cold rolling process to a final thickness of Q, jf m1Ill, and then heated in a continuous annealing furnace. After annealing, a coating baking process was performed. The conditions for continuous annealing were as follows: After passing the plate for 3 minutes at 100°C in a dry nitrogen atmosphere,
After cooling at a cooling rate of ℃/win, some parts of the louver become 0.
A strain of 3% was added. Coating baking conditions are board temperature 0.
1 minute at 0″C.

The samples or coils of Examples 1 to ■, Comparative Example I, and 1 are as follows:
After measuring the Vickers hardness, it is sheared to a size of 30x tOW, and after laminating, it is dx for dx at a temperature of 710″C.
Gas (composition H2: /J% tCo: t%
Strain relief annealing was performed in eC02: k % e dew point °C, residual Hz), and zero analysis was performed to examine decarburization properties. The above results are shown in Table 9.

As described above, the electrical steel sheet of the present invention is different from the conventional semi-processed electrical steel sheet, and has precipitates consisting of fine carbides dispersed with an average distance of 0.117 mm or less in the crystal grains during punching of the steel sheet, and has a Vickers hardness. 730 or higher, it has excellent punching properties, and according to the present invention, the above-mentioned semi-puda Sesho electromagnetic i7, /, ni, Ds Egakaki in the structure of the above-mentioned excellent punching properties. Kameko micrograph showing the state of precipitation and dispersion of fine carbides (x t
oooo ), Figure 3 is a diagram showing the relationship between the average distance between precipitated carbides and Vickers hardness, and Figure 41 is a diagram showing the influence of aging temperature and aging time on hardness (Hma) of a steel plate. .

Patent applicant: Kawasaki Steel Corporation Kinsha Figure 1

Claims (1)

[Claims] 1. Si/% or less Furnace m l O, r % or less + Knθ,
/~O,j%,Q O,0-~θ,or%r P o
, t%% or less of semi-processed electrical steel sheet with the balance substantially composed of Fe, which has precipitates consisting of dispersed fine carbides with an average distance of 06#μ layer or less in the crystal grains during punching of the steel sheet, Hardness is 730 or more,
A semi-processed electrical steel sheet with excellent punchability that is subjected to strain relief annealing treatment after punching. 2.81/% or less + At o-s%% or less Mll
O-/Import o,t%I O0,0-~0005%-P O
,/%below. After cold-rolling the hot-rolled steel sheet, the remainder of which is essentially Fe, to obtain a cold-rolled steel sheet with a final thickness, the cold-rolled steel sheet is
Annealing of 0.2~j xi at 9°C to 0°C, followed by at most 300°C at a cooling rate of 400°C/+min or more.
Rapidly cool down to 300~! After adding a strain of 0.1% or less as necessary between θ℃, 1tO-110℃
The average distance between the grains is 0.41 pm, characterized by slow cooling at a cooling rate of 100'C/ff1in or less.
A method for producing a semi-processed electrical steel sheet having excellent punchability and having a Vickers hardness of /30 or more and having precipitates made of dispersed fine carbides as described below. 3.81/% or lesst 14 o,z % or lesse Kn
O, 1~0.3%e OO, 02~0.0! Arc IP
O,/% or less! After cold-rolling a hot-rolled steel sheet with the remainder substantially consisting of re to obtain a cold-rolled steel sheet with a final thickness, the temperature of this cold-rolled steel sheet is θθ~t! θ at θ℃,! ~jI! 11 m of annealing, followed by cooling to 300-250° C. with a cooling rate of 400° C./m i* or more, and 0.000° C. as necessary within this temperature range. Add a strain of % or less to
10~/10 at O℃! It has a patented aging treatment of l@6, has precipitates consisting of dispersed fine carbides with an average distance of 0.41μ weight or less in the ridged grains, and has punchability of Vickers hardness / 30 or more. Excellent method for manufacturing electromagnetic steel sheets using the Shichimon process. 4.817% or less, AJ O,r % or less e Mu
O, / ~O0j%e OO,02~0.01%e P
O, /≦ or less. After cold-rolling a hot-rolled steel plate with the remainder substantially consisting of Fs to obtain a cold-rolled steel plate with a final thickness, the cold steel & paste 00~
Annealed at 930°C for 0014mm, followed by 40mm
Rapid cooling to 200℃ at a cooling rate of 0℃/win or more,
During this rapid cooling, between 30θ and -00℃, O, S
Precipitation consisting of fine carbides dispersed within grains with an average distance of 0*4'/JIB or less, characterized by applying a strain of 0.0% or less and then winding the steel plate at a temperature of 100 to tO℃. A method for producing a semi-processed electrical steel sheet having a Vickers hardness of /30 or more and having excellent punchability. 5, Si/% or less t AJ O,, t % or less * Kn
O,/ ~0,! r%* Oo-oλ~0.0k%
# P O, / % or less. After cold-rolling a hot-rolled steel sheet with the remainder substantially consisting of Fe to obtain a cold-rolled steel sheet with a final thickness, this cold-rolled steel sheet is
0.0 at 00℃. ! ~! f win annealing, followed by rapid cooling to 1k0°C at a cooling rate of 400°C/■im or more, and during this rapid cooling, a strain of 0.2- or less is added as necessary, and then /10 lθ~/lOs between ~210℃
The average distance within the crystal grains is 0. A method for producing a semi-processed electrical steel sheet having precipitates consisting of dispersed fine carbides of fpm or less and having a Vickers hardness of /30 or more and excellent punchability.