JPS61119618A - Manufacture of electrical sheet for iron core material in small reposer - Google Patents

Abstract

PURPOSE:To obtain inexpensively the titled steel sheet superior in magnetic flux density, by hot rolling steel slab contg. specified quantities of C, Si, Mn, Al and cold rolling in 2 times said plate interposing intermediate annealing under a specified condition. CONSTITUTION:Steel slab having compsn. contg. <=0.020wt% C, <=1.0% Si, 0.1-1.0% Mn, <=0.40% Al is hot rolled. This plate is immediately cold rolled firstly to intermediate thickness, then the sheet is annealed continuously at 675-750 deg.C for 15sec-2min, next cold rolled secondarily under condition of 3-7% draft to the final thickness. Successively, said sheet is strain-removing annealed, to obtain magnetic steel sheet having >=1.08 ratio of flux density B50C at right angle in rolling direction to that B50L in rolling direction. The obtained sheet has strong anisotropy and is suitable for iron core material of small reposer.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for manufacturing an electromagnetic steel sheet with strong anisotropy suitable for use as a core material of a small stationary device.

(Prior Art) There are various types of stationary devices, ranging from large transformers for electric power to small transformers for audio equipment and ballasts for fluorescent lamps. Among these, grain-oriented silicon steel plates are used for the cores of power and distribution transformers, while non-oriented ROM plates are mainly used for the cores of small stationary devices such as audio equipment and ballasts. is normal.

Grain-oriented silicon steel sheets have much better magnetic properties in the rolling direction than in other directions. Therefore, large transformers are designed so that the rolling direction of grain-oriented silicon steel sheets coincides with the direction in which magnetic flux flows when assembled to an iron core. On the other hand, since small static machines need to be manufactured at low cost, simple processing methods are generally adopted even if magnetic flux flows in directions other than the rolling direction.

However, even in a small static machine, it is desirable that the proportion of magnetic flux flowing in the rolling direction be as large as possible, and the characteristics in the rolling direction are still important.

(Problem to be solved by the invention) In this regard, it is sufficient to use a grain-oriented silicon steel sheet as the core material for a small stationary device, but compared to a non-oriented electrical steel sheet, a grain-oriented silicon steel sheet is sufficient. It is generally not used because of its value.

The purpose of the present invention is to advantageously solve the above-mentioned problems, and to propose an inexpensive electrical steel sheet that has excellent properties in the rolling direction, particularly magnetic flux density, and is particularly suitable as an iron core material for small stationary machines.

(Means for Solving the Problems) In order to achieve the above object, the inventors have reexamined each manufacturing process of electrical steel sheets in detail, and as a result, they have developed two cold rolling processes including intermediate annealing. By adopting the rolling method and limiting the annealing temperature in the intermediate annealing and the rolling reduction in the subsequent second cold rolling to predetermined ranges, it was found that the anisotropy of the electrical steel sheet was significantly strengthened. This led to the completion of this invention.

That is, this invention provides C: 0,020 wt% or less (hereinafter simply expressed as %), Si: 1.0% or less, M
After hot rolling a steel slab having a composition containing n: 0.1 to 1.0% and A1: 0.40% or less, two intermediate annealing steps are performed without going through hot-rolled plate annealing. In manufacturing electrical steel sheets by cold rolling and then final annealing or not, continuous annealing is performed for 15 seconds to 2 minutes at a concentration range of 675 to 750°C for the intermediate annealing, and
The magnetic flux density in the rolling direction is 550 I with respect to the magnetic flux density B sec in the direction perpendicular to the rolling direction after strain relief annealing, characterized in that the second cold rolling is performed under conditions of a rolling reduction ratio of 3 to 7%.
This is a method for manufacturing an electrical steel sheet for iron core material of a small stationary device, in which the ratio of , is 1.08.

This invention will be specifically explained below with reference to the experimental results that led to this invention.

c: o, ooa%, 3i: 0,10%, 1y
jn: 0.27% and l! : 0,00
Thickness 2ma+ with a composition of 1% Fe and the remainder Fe
A hot-rolled sheet is pickled and then immediately heated to
After the second cold rolling to an intermediate thickness of 0.50 to 0.56 as, it was rolled to a thickness of 600 to 600 in a hydrogen/nitrogen mixed atmosphere.
Intermediate annealing was performed for 1 minute in a temperature range of 800°C. Then, a second cold rolling was performed at each rolling reduction ratio of 0 to 10% to obtain a final cold rolled sheet with a thickness of 0.5 mm. Epstein specimens were cut from each cold-rolled plate thus obtained in the rolling direction (hereinafter referred to as the downward direction) and in the direction perpendicular to the rolling direction (hereinafter referred to as the C direction), and subjected to strain relief annealing at 750 ° C. for 2 hours in a nitrogen atmosphere. Afterwards, the magnetic flux densities SSO in the L direction + C direction, the backward direction, and the C direction were measured.

The obtained results are summarized and shown in FIGS. 1a, b, and c.

As is clear from Figure 1a, the annealing temperature of intermediate annealing is 6
In the range of 75 to 150°C and the second cold rolling reduction rate is 3.
~7%, the magnetic flux density in the direction increases significantly, and as shown in C of the same figure, B50L/Bs0c≧1.0
It exhibited strong anisotropy of 8.

(Function) Next, the reason why the component composition of the material slab of the present invention is limited to the above range will be explained.

C: 0.020% or less C is an element harmful to magnetic properties, so it is preferable to reduce it as much as possible. (A range of 120% or less is acceptable.

Si: 1.0% or less, AJ! : 0.40% or less Both Si and Al are useful elements for increasing electrical resistance and lowering iron loss, but if added in large amounts, they will lead to a decrease in magnetic flux density and increase costs, so they should be used separately. Si: limited to 1.0% or less, AI220, 40% or less.

Mn: 0.1-1.0% Mn effectively contributes to improving hot brittleness, but 0.1%
If less than 1.0%, the effect of addition is poor, while if it exceeds 1.0%, the magnetic properties will deteriorate, so it is necessary to contain it in the range of 0.1 to 1.0%.

Next, this invention will be specifically explained in order of manufacturing steps.

From the melting process to the hot rolling process in steel manufacturing, any conventionally known method may be used, and the point is to obtain a hot rolled sheet having the above-described preferred component composition. Hot-rolled sheets are usually 1.6 to 2
．． The thickness is about 6III11, but is not particularly limited. The obtained hot rolled sheet is subjected to the first cold rolling immediately after pickling without being subjected to hot rolling (k annealing).

Although it is well known that annealing a hot-rolled sheet improves the fume properties, especially the magnetic flux density, such heat treatment has the disadvantage of increasing costs. However, since a product with a sufficiently high magnetic flux density in the L direction can be obtained even if the hot-rolled sheet is annealed, it was decided not to perform hot-rolled sheet annealing in this invention.

The steel plate made into an intermediate thickness by the first cold rolling is then subjected to intermediate annealing, but if the annealing temperature is less than 675°C or exceeds 750°C, as shown in Figure 1 above, Because strong anisotropy cannot be changed, intermediate annealing is performed at 675 to 75.
It is necessary to carry out the test in a temperature range of 0°C. Furthermore, if the time required for intermediate annealing is less than 15 seconds, recrystallization will not proceed sufficiently.
On the other hand, if the annealing time exceeds 2 minutes, the production efficiency decreases, so the annealing time was limited to a range of 15 seconds to 2 minutes.

After this intermediate annealing, the steel plate is cold rolled a second time to obtain a cold rolled plate of the final thickness. At this time, in order to obtain a sufficiently satisfactory anisotropy, as shown in Figure 1 above, Reduce the reduction rate to 3~
It is necessary to limit the range to 7%.

The cold-rolled sheet thus obtained may be shipped to a consumer as a product as it is, or may be further subjected to RN annealing before being shipped. However, if shipped as final cold rolled,
After the customer punches the core into a small static device core, it must be annealed to remove strain.

Note that the insulating WIM is usually coated and shipped, but there is no particular limitation.

(Example) Example 1 CO, 013%, 3i 0.95%, Mn 0.2
6% and a composition containing 10.25% A2,3
Immediately after pickling, a 1-thick hot-rolled sheet is cold-rolled for the first time to achieve a 0.52
After having a thickness of 6rgra, intermediate annealing was performed at 700°C for 11 minutes in a nitrogen/hydrogen mixed atmosphere, and then the rolling reduction was 5%.
A final cold rolling was performed to obtain a cold rolled sheet with a thickness of 0.5 mm.

Epstein test pieces were cut out from the cold-rolled sheets obtained in this manner, and after annealing in nitrogen at 750°C for 2 hours, magnetic properties were measured.

As a comparative material, a material with the same components was intermediately annealed at 800°C.
A similar investigation was conducted on samples treated for 1 minute and other conditions under the same conditions.

The magnetic properties of both were as follows.

(Effect of the invention) Thus, according to the present invention, the 850L'85
(It is possible to use an electrical steel sheet called IO31,08, which has strong anisotropy and is suitable for the iron core material of a small stationary device.

[Brief explanation of the drawing]

Figure 1 a, b, and C are the average magnetic flux density B5o (average of L + C) in the L direction and C direction, and B
50L/B50c, intermediate annealing temperature and 2
It is a graph showing the influence of the rolling reduction ratio of the second cold rolling. Patent applicant: Kawasaki Steel Co., Ltd. 2nd rolling reduction rate ζ%) Figure 1 2nd rolling a/f:, T prison (curse)

Claims (1)

[Claims] 1. A steel slab having a composition containing C: 0.020 wt% or less, Si: 1.0 wt% or less, Mn: 0.1 to 1.0 wt%, and Al: 0.40 wt% or less. After hot rolling, the above intermediate annealing is performed without hot rolling, cold rolling is performed twice with intermediate annealing, and then final annealing is performed or not. After strain relief annealing, which is performed by continuous annealing for 15 seconds to 2 minutes at a temperature range of 675 to 750°C, and a second cold rolling is performed at a rolling reduction ratio of 3 to 7%. A method for manufacturing an electromagnetic steel sheet for iron core material of a small static machine, wherein the ratio of magnetic flux density B_5_0_L in the rolling direction to magnetic flux density B_5_0_C in the direction perpendicular to rolling is 1.08 or more.