JPH0331419A - Production of semi-processed non-oriented electrical steel sheet having excellent magnetic characteristics - Google Patents

Abstract

PURPOSE:To produce the semi-processed non-oriented electrical steel sheet having excellent magnetic characteristics by subjecting a low carbon steel slab to a hot rolling, descaling and annealing under specific conditions and then further subjecting the steel sheet to a warm rolling, annealing and skin pass rolling under specific conditions, then to a working and strain relief annealing. CONSTITUTION:The low carbon steel slab contg., by weight%, 0.001 to 0.04% C, 0.01 to 2.5% Si, <0.20% Al, 0.1 to 1.2% Mn, 0.03 to 0.11% P, <0.015% S, and <0.0050% N or further contg. B in a range where 0.5 to 1.8 B/N (by weight) is attained is hot rolled at 700 deg.C to Ar3 transformation temp. or below hot finish rolling temp. and is coiled at >=700 deg.C. The coil is self-annealed by its own possessed heat. This steel sheet is cold roller after the scale generated by the hot rolling is removed and in this case, the total strains to be imparted by the cold rolling are converted to a logarithmic strain and >=50% thereof is rolled warm at 100 to 400 deg.C; thereafter, the steel sheet is annealed for <3 minutes at 700 to 900 deg.C. The steel sheet is in succession subjected to the working, such as blanking after the skin pass rolling, then to the strain relief annealing. The semi-processed non-oriented electrical steel sheet which has a high magnetic flux density and less iron loss is produced with good productivity.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a method for manufacturing the magnetic properties described in item 2, which has high magnetic flux density and low iron loss and does not involve semi-processing.

(Prior Art) In recent years, reducing energy consumption has become an important issue regardless of field, and there is a growing demand for higher efficiency in electrical equipment.

Therefore, there is a desire for a material that has both low iron loss and high magnetic flux density in terms of the magnetic properties described in item 2, which is widely used as an iron core material for motors, transformers, and the like.

As is well known, the magnetic properties described in item 2 can be divided into fully processed materials and semi-processed materials depending on the manufacturing method. Fully processed materials are used as products after final annealing by the steel sheet manufacturer, while semi-processed materials are subjected to annealing, skin pass, etc. at the steel sheet manufacturer's side, and processing such as punching and shearing at the steel sheet consumer. Afterwards, it is further subjected to strain relief annealing to obtain predetermined characteristics.

Compared to fully processed materials, semi-processed materials undergo grain growth during strain relief annealing, resulting in lower iron loss, but on the other hand, magnetic flux density decreases. In order to improve this point, semi-processed materials have been published in Japanese Patent Application Laid-Open Nos. 57-203718 and 61-4.
As shown in Japanese Patent No. 4125, a method of performing cold rolling and annealing after hot-rolled sheet annealing, and a method of intervening annealing during cold rolling have been proposed. Although these methods are highly effective in improving magnetic properties, they require longer steps such as annealing the hot-rolled sheet and annealing during cold rolling, resulting in decreased productivity and increased cost.

(Problems to be Solved by the Invention) The present invention achieves improvement of the magnetic properties of the magnetic properties described in item 2 without semi-processing, particularly high magnetic flux density, without using hot-rolled sheet annealing, etc., and achieves high productivity and It is an object of the present invention to obtain the magnetic properties described in item 2 without semi-processing, which are low cost and have excellent magnetic properties.

(Means for solving the problem) The gist of the present invention is that C: o, oot at 2%
~0.04%, SI: 0.01~2.5%, Ag: 0
．． 20% or less, Mn: 0. l=1.2%, P: 0.
03-0.11%, S: 0.015% or less, N: 0
．． After hot rolling and descaling a steel piece containing 0.050% or less and the remainder consisting of iron and unavoidable impurities, the total strain imparted during cold rolling is converted into logarithmic strain, and 5096 or more of that is 100%. A patented method for producing an electrical steel sheet, characterized by warm rolling at ~400°C, annealing at 700-900°C for less than 3 minutes, skin pass rolling, punching, etc., and strain relief annealing. Yes, other features include C in weight%
:0.001-0.04%, SI:0. Ol~2,5
%, Hep20, 20% or less, Mn: 0.1-1.2%,
P: 0.03-0.11%, S: 0.015%
Hereinafter, after hot rolling and descaling a steel billet containing N: 0.0050% or less, a weight ratio of B/N with BIN of 0.5 to 1.8, and the remainder consisting of iron and unavoidable impurities. The total strain imparted during cold rolling is converted into logarithmic strain, and at least 50% of it is warm rolled at 100 to 400°C, annealed at 700 to 900°C for less than 3 minutes, and then skin pass rolled. The method for producing magnetic properties according to item 2 does not include a semi-process that produces excellent magnetic properties, which is characterized by carrying out strain relief annealing after processing such as punching, and if necessary, the finishing temperature is increased during hot rolling. below the Ar3 transformation point and 700°C or higher, and the winding after hot rolling is 700°C or higher.
(Self-annealing is performed at a temperature of 10°C or higher.

(for production) The present invention will be explained in detail below.

Since C is a harmful element in terms of magnetic properties and deteriorates the magnetic properties, it should be kept at 0.04% or less. In order to further improve the magnetic properties, it is desirable to reduce the content to 0.005% or less using a vacuum degassing device or the like. However, from an industrial point of view, there is a limit to decarburization during steel manufacturing, and it is set at 0.001% or more.

St is effective in deoxidizing and increasing the electrical resistance of steel sheets and lowering the iron loss value, and in order to achieve this effect, 0.01%
The above is necessary. However, as the content increases, the magnetic flux density decreases and costs increase, so it is set to 2.5% or less.

Like Sl, Al2 is an effective element used for deoxidation and for increasing specific resistance and improving core loss, but its addition causes an increase in cost, so it is limited to 0.20% or less.

Mn is contained in an amount of 0.1% or more to prevent red brittleness during hot rolling. On the other hand, excessive content causes deterioration of magnetic properties, so the content should be 1.2% or less.

P is contained in an amount of 0.03% or more in order to increase the hardness of the steel plate and improve the punching property in snowy areas. However, if the content is too large, embrittlement will be significant, so the upper limit is set at 0.11%.

S is 0.015 because it inhibits grain growth and worsens iron loss.
% or less, preferably 0.005% or less.

Since N is an element that inhibits grain growth and is harmful to magnetic properties, the value is 0.0.
050% or less. Preferably it is o, ooao% or less. Further, by fixing N, grain growth properties are improved, and in order to further improve iron loss, B is added in an amount equal to or less than N equivalent, if necessary. If B/N is less than 0.5 with respect to Nm, no effect will be obtained, while if it is more than 1.8, the opposite effect will occur, so B/N-0,
5 to 1.8.

The slab made of the melted and cast components is then hot rolled. If the finishing temperature at this time is 700°C or higher below the Ara transformation point, (100), (110)
Since the texture develops, it is effective in improving magnetic properties when combined with warm rolling, which will be described later. Moreover, if the coiling after hot rolling is performed at 700° C. or higher and self-annealing is performed, the magnetic properties are further improved. The reason why the coil is wound at 700° C. or higher is to ensure that the hot-rolled coil retains its own heat.

Next, after degreasing, cold rolling is performed, and the temperature conditions over part or all of this rolling are important requirements in the present invention. In order to improve the magnetic properties, particularly to increase the magnetic flux density, it is necessary to increase the total strain by 50% or more of the total strain converted into logarithmic strain.

When the rolling temperature range is less than 100°C, the effect of improving magnetic properties disappears, while when it exceeds 400°C, rolling operations are hindered. Rolling in this temperature range does not need to cover the entire reduction, but if it covers 50% or more in terms of logarithmic strain, it is in the early or middle stage of cold rolling.

No matter which stage is used, the effect of improving magnetic properties will appear.

After cold rolling, continuous annealing is performed, and the temperature is set at 700 to 900° C. in order to improve magnetic properties and reduce costs. Further, the heat retention time is set to less than 3 minutes in order to improve productivity while ensuring magnetic properties.

After further skin pass rolling, it becomes a product. The reduction amount is not particularly limited, but is preferably 3 to 8% in order to improve magnetic properties. After processing such as punching, it is annealed to remove strain.

(Example) The magnetic properties of each component shown in Table 1 without semi-processing described in Section 2 were manufactured and their magnetic properties were investigated. Table 2 shows the manufacturing conditions of hot rolling, cold rolling, annealing, and skin pass, as well as the magnetic properties of the product.

The test material was subjected to strain relief annealing at 750°C for 2 hours.

As is clear from Table 2, materials that have been rolled at a reduction ratio of 50% or more in terms of logarithmic strain in the temperature range of 100 to 400°C have higher magnetic flux density and lower iron loss than comparative materials. ing. Magnetic properties are further improved by combining low-temperature finishing with hot rolling and high-temperature winding.

(Effect of the invention) By manufacturing the magnetic properties described in item 2 without semi-processing according to the present invention, a material with high magnetic flux density and low iron loss can be produced with high productivity and low cost without hot-rolled plate annealing. You can get it at

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Claims (1)

[Claims] 1. C: 0.001-0.04% Si: 0.01-2.5% Al: 0.20% or less Mn: 0.1-1.2% P: 0.03 to 0.11% S: 0.015% or less N: 0.0050% or less Convert the strain to logarithmic strain, and convert more than 50% of it to 100
A semi-process with excellent magnetic properties characterized by warm rolling at ~400°C, annealing at 700-900°C for less than 3 minutes, skin pass rolling, processing such as punching, and strain relief annealing. A method for manufacturing non-oriented electrical steel sheets. 2. Production of a semi-processed non-oriented electrical steel sheet with excellent magnetic properties according to claim 1, which contains a B:N weight ratio of 0.5 to 1.8 by weight. Method. 3. The method for producing a semi-processed non-oriented electrical steel sheet with excellent magnetic properties as set forth in claim 1 or 2, wherein the finishing temperature during hot rolling is lower than the Ar_3 transformation point and 700° C. or higher. 4. Semi-processed non-oriented electrical steel sheet with excellent magnetic properties according to claim 1, 2 or 3, which is coiled at a temperature of 700° C. or higher and self-annealed after hot rolling. manufacturing method.