JPH0676621B2 - Manufacturing method of semi-processed non-oriented electrical steel sheet with excellent magnetic properties and weldability - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing a semi-process non-oriented electrical steel sheet mainly used for small static devices.

[Conventional technology]

Non-oriented electrical steel sheets are mainly used for small static devices for audio equipment and ballasts. In the EI core, which is an example of a small static device, as shown in FIG. 1, the plate cutting has a ratio of 75% of the magnetic path in the rolling direction (hereinafter referred to as the L direction). An excellent non-oriented electrical steel sheet is required.

The following methods have been proposed as a method for producing a steel sheet having excellent magnetic properties in the L direction.

In Japanese Examined Patent Publication No. 56-43294, [Si] 0.1 to 1.0%, [TA]
l] 0.007% or less, and the cold rolling rate of the second cold rolling of the manufacturing method in which the hot rolled sheet is cold rolled twice with intermediate annealing sandwiched is set to 2 to 15%, and the roughness of the steel sheet after rolling is 15μ. -In. RMS A method characterized in that it is carried out with a rolling roll having a temperature of not more than RMS.

In JP-A-61-119618, [Si] 1.0% or less, [A]
l] In a manufacturing method in which a slab containing 0.4% or less of other materials is hot-rolled, and then cold-rolled twice with intermediate annealing sandwiched between hot-rolled sheet annealing, the intermediate annealing is performed at 675 ° C to 750 ° C for 15 seconds to 2 minutes. A method characterized by performing continuous annealing and performing a second cold rolling at a rolling reduction of 3 to 7%.

On the other hand, the iron core of a small static device is punched out from a steel sheet into a predetermined shape, laminated and then clamped. One of the methods is welding. For example, in the case of EI core, after punching into E type and I type, they are laminated and annealed at 750 ° C. for about 2 hours. Next, a bobbin wound with a copper wire is inserted into an E-type stack, and then the I-type is welded to the E-type to form an iron core. The E-type and I-type welding is usually performed by TIG welding. At this time, the strength is not so required, but the ease of forming beads is a problem. That is, it is preferable to use a steel plate having a wide bead so that the E type and the I type can be welded even if the position accuracy of the torch is poor. By the way, it is possible to increase the welding conditions such as increasing the welding current, lowering the welding speed, and widening the bead width, but the characteristics of the static device are increased due to increased electrode wear, decreased productivity, increased heat input, thermal strain, etc. However, in the above-mentioned conventional technique, the weldability after magnetic annealing was not satisfactory.

Conventionally, regarding the weldability improvement of the laminated core of the non-oriented electrical steel sheet having an organic-containing coating, Japanese Patent Publication No. Sho 49-6744,
Although proposed in JP-B-49-19078, these are all prior to magnetic annealing, and improvement in weldability after magnetic annealing in which the organic substances in the film are removed, that is, improvement in bead width, has been conventionally proposed. It has not been.

[Problems to be Solved by the Invention]

INDUSTRIAL APPLICABILITY The present invention is a semi-process non-directional non-directional semi-process for a small static device having excellent magnetic properties in the L direction and excellent weldability, which can solve the drawbacks of the above-described prior art in which both magnetic properties and weldability could not be satisfied. It is an object to provide a method for manufacturing an electromagnetic steel sheet.

[Means for Solving the Problems]

 The gist of the present invention is as follows.

(1) [C] 0.015% or less, [Si] 0.1 to 1.5%, [Mn]
0.1 to 1.5%, [P] 0.15% or less, [S] 0.008% or less,
(Sol.Al) 0.01-1.0%, (TN) 0.0050% or less, (T.
O] including 0.02% or less, [sol.Al] / [Si] ≧ 0.02, [Al ₂ O ₃ ] / ([SiO ₂ ] + [MnO] + [Al ₂ O ₃ ]) × 100 ≧
When a slab satisfying 40% and having the balance of iron and unavoidable impurities is hot-rolled and then subjected to two cold-rollings with an intermediate annealing, the average crystal grain size after the intermediate annealing is 10 to 15 μm, Two
Semi-process with excellent magnetic properties and weldability, characterized in that the reduction ratio of the cold rolling of the second time is 3 to 10% and the surface roughness of the steel sheet after the second cold rolling is 15 μ-in. RMS or less. Manufacturing method of non-oriented electrical steel sheet.

(2) The method for producing a semi-processed non-oriented electrical steel sheet having excellent magnetic properties and weldability according to the above item 1, wherein the hot rolled sheet is annealed at 700 to 1000 ° C.

The present inventors have made diligent efforts to develop a method for manufacturing a semi-process non-oriented electrical steel sheet for a small static device, which has excellent magnetic properties in the L direction and excellent weldability. The newly obtained findings are described below.

First, regarding the weldability, the present inventor has found that TIG after magnetic annealing
Research was repeated to widen the bead width during welding. As a result, [sol.Al] / [Si], [Al ₂ O _3] / ([SiO _2] + [M
It was newly discovered that the bead width can be widened by limiting nO] + [Al ₂ O ₃ ]) × 100, [sol.Al] to a specific range. FIG. 2 shows the result of an experiment conducted by the present inventor. [C] 0.003%, [Si] 0.9 to 1.1%, [Mn] 0.2%,
[P] 0.07%, [S] 0.0022 to 0.0039%, [TN] 0.001
9 to 0.0035%, [TO] 0.007 to 0.012%, [sol.Al] 0.00
Molten steel containing 1 to 1.3% was melted by changing the deoxidizing method, and the composition of oxide inclusions and the [sol.Al] / [Si] ratio were changed to form a slab. Subsequently, it was hot rolled, cold rolled to a sheet thickness of 0.50 mm, continuously annealed, coated with an insulating coating, and annealed at 750 ° C. for 2 hours. And TIG welding, welding current 100A, welding speed 65cm / min, arc length 2mm, argon flow rate 5l / min, tightening pressure 25kgf / cm ² , electrode: 2% thorium tungsten.
The welding was performed under the welding condition of 1.6 mmφ. [Al ₂ O ₃ ] / at this time
([SiO ₂ ] + [MnO] + [Al ₂ O ₃ ]) × 100 and [sol.Al]
The relationship between / [Si] and the bead width is shown in FIG. Than this,
[Al ₂ O ₃ ] / ([SiO ₂ ] + [MnO] + [Al ₂ O ₃ ]) × 100 ≧
It was found that when 40% and [sol.Al] / [Si] ≧ 0.02, the bead width stably increased to 3 mm or more.

In the experiment of FIG. 3, [C] 0.002%, [Si] 0.10 to 0.32
%, [Mn] 0.2%, [P] 0.07%, [S] 0.0033 to 0.004
7%, [N] 0.0025 to 0.0032%, [TO] 0.011 to 0.014
%, [Sol.Al] 0.001 to 0.05% was melted. The composition of oxide inclusions is [Al ₂ O ₃ ] / ([SiO ₂ ]
+ [MnO] + [Al ₂ O ₃ ]) x 100 to 47-59%, and [sol.A
The value of l] / [Si] was changed to make a slab. Hot roll this,
Cold rolled to a thickness of 0.50 mm, continuously annealed, coated with an insulating film,
Made as a product. The subsequent sample preparation, magnetic annealing, and welding conditions are the same as in the experiment of FIG. From this, it became clear that the absolute amount of [sol.Al] should be 0.01% or more.

As described above, it was newly found that the components in the steel and the composition of the oxide-based inclusions influence the bead width after magnetic annealing (the invention based on this finding was filed as Japanese Patent Application No. 63-333830). Already).

Although the above-mentioned experiment is an experiment by a single cold rolling method, the present inventor also conducted an experiment of a double cold rolling method with intermediate annealing, and an experiment when hot-rolled sheet annealing was performed in addition to this. It was confirmed that the difference in the process did not affect the bead width after magnetic annealing.

By the way, in Japanese Patent Publication No. 56-43294, [Si] 0.1
~ 1.0%, [T.Al] 0.007% or less hot rolled sheet with intermediate annealing sandwiched between two cold rolling, the cold rolling rate of the second cold rolling is set to 2 to 15%, and the steel sheet after rolling Roughness of 15μ ~ in. RM
S. A method for manufacturing a non-oriented electrical steel sheet having a high magnetic flux density in the L direction, which is characterized in that it is performed using a rolling roll having the following properties, has been proposed. However, with this method [T.Al]
Is limited to 0.007% or less, and in the specification, aluminum is present in the form of various precipitates and inclusions, which are unfavorable crystals that lower the magnetic permeability during crystal grain growth by annealing. Imagine that the azimuth has developed,
It is stated that when the content of [T.Al] exceeds 0.007%, the magnetic flux density in the L direction cannot be increased. On the other hand, in order to widen the bead width as described above, [sol.Al] is 0.01
% Or more, and it is essential that the oxide inclusions have a composition with a large proportion of Al ₂ O ₃ . Therefore, the inventor of the present invention contains 0.01% or more of [sol.
The inventors have earnestly worked on the invention of a method for producing a non-oriented electrical steel sheet having a composition with a large proportion of Al ₂ O ₃ and having a wide bead width after magnetic annealing and a high magnetic flux density in the L direction.

In the experiment of FIG. 4, [C] 0.003%, [Si] 0.34%, [M]
n] 0.2%, [P] 0.07%, [S] 0.0032%, [TN] 0.0
Contains 021%, [TO] 0.007%, [sol.Al] 0.26%,
[Al ₂ O ₃ ] / ([SiO ₂ ] + [MnO] + [Al ₂ O ₃ ]) × 100
51% slab is hot-rolled, intermediate annealing is sandwiched in the double cold-rolling process, with an intermediate thickness of 0.51 to 0.57 mm, annealed at various intermediate annealing temperatures, and then 0 to 15% cold rolled. 2 at a rate
After the cold rolling for the third time, the roughness of the steel plate is 13-14 μ-in.RM.
The final product plate thickness was 0.50 mm. And 750 ℃
The magnetic properties were evaluated by performing magnetic annealing for × 2 hours. FIG. 4 shows the relationship between the average grain size after the intermediate annealing, the second cold rolling rate and the magnetic flux density in the L direction at this time. From the experimental example of FIG. 4, the intermediate crystal grain size is 10 to 15 μm, and the second cold rolling rate is 3 to 10
It can be seen that the magnetic flux density in the L direction becomes high when%.
That is, by limiting the intermediate crystal grain size and the second cold rolling rate to a narrow range, even if 0.01% or more of [sol.Al] is contained, L
Succeeded in increasing the magnetic flux density in the direction, for example Si +
It was possible to obtain a magnetic flux density B ₅₀ in the L direction of 1.82 T or more with a steel sheet containing 0.60% Al.

The relationship between the temperature and time of intermediate annealing and the average crystal grain size is
Strictly about one material, but this relationship shifts when the constituent materials change. For example, the recrystallization start temperature and the grain growth rate change depending on the Si content. An example of an experiment conducted on this relationship is shown in FIG. (Si) 0.1
%, 1.0%, 1.8%, with 0 other elements other than iron.
Hot-rolled sheet of 005% or less component material is cold-rolled at a reduction rate of 82%, the soaking time of intermediate annealing is fixed at 30 seconds, the soaking temperature is changed, and the relationship with the average grain size is investigated. did. From this, Si
It can be seen that the average grain size obtained varies depending on the content even if the soaking time is the same. Therefore, in the present invention, the condition of the intermediate annealing is defined by the average crystal grain size which has a metallurgical meaning.

In the experiment of FIG. 6, the hot rolled sheet used in the experiment of FIG. 4 was annealed at various temperatures. Then, with an intermediate thickness of 0.52 to 0.56 mm, intermediate annealing was performed, and the average grain size after intermediate annealing was 12
μm. Then, the second cold rolling with a reduction rate of 3 to 10% was performed, the roughness of the steel sheet was 13 to 14 μ-in. RMS, and the final product sheet thickness was 0.50 mm. And 750 ℃ × 2
Magnetic annealing was performed for a period of time to evaluate the magnetic properties. From the experimental example of FIG. 6, it can be seen that the magnetic flux density increases by about 100 G when the hot rolled sheet is annealed at 700 ° C. or higher.

(Relationship with Conventionally Known Technology) In Japanese Patent Publication No. 56-43294, hot-rolled sheets containing [Si] 0.1 to 1.0% and [T.Al] 0.007% or less are cold-rolled twice with intermediate annealing sandwiched therebetween. The cold rolling rate of the second cold rolling of the manufacturing method is set to 2 to 15%, and the roughness of the steel sheet after rolling is 15μ.
A method has been proposed, which is characterized in that rolling is performed with a rolling roll having a temperature of −in. RMS or less.

However, since the upper limit of [T.Al] is 0.007% in this technique, the bead width during welding after magnetic annealing becomes narrow.

On the other hand, the present invention contains [sol.Al] 0.01% or more,
[Sol.Al] / [Si], [Al ₂ O _3] / ([SiO _2] + [MnO]
By controlling + [Al ₂ O ₃ ]) × 100 within a narrow range, excellent weldability is achieved, and the average grain size after intermediate annealing and the reduction rate of the second cold rolling are controlled within a narrow range. For example, even if the content of [sol.Al] is 0.01% or more, it has succeeded in obtaining excellent magnetic properties, and is a technique that satisfies both the magnetic properties and weldability after magnetic annealing. Therefore, the present invention provides
It is understood that the technique is completely different from the technique described in Japanese Patent Publication No. 56-43294.

In JP-A-61-119618, [Si] 1.0% or less, [A]
l] In a manufacturing method in which a slab containing 0.4% or less of others is hot-rolled, and then cold-rolled twice with intermediate annealing sandwiched between hot-rolled sheet annealing, the intermediate annealing is continuously performed at 675 to 750 ° C for 15 seconds to 2 minutes. A method has been proposed in which annealing is performed and the second cold rolling is performed at a rolling reduction of 3 to 7%. But with this technology,
There is no description of weldability after magnetic annealing, there is no idea of limiting the range of components and oxide-based inclusions in the steel, and in the present invention, the roughness of the steel sheet after the second cold rolling is determined. It is indispensable to set it to 15 μ-in. RMS or less in order to increase the magnetic flux density in the L direction, but it is understood that there is no description about it and it is a technology completely different from the present invention.

[Reason for limiting the requirements]

[C]: When C exceeds 0.015%, not only is it harmful to the magnetic properties, but also the magnetic aging due to the precipitation of C becomes remarkable and the magnetic properties deteriorate, so 0.015% or less, preferably 0.010% or less.

[Si]: Si is an element that reduces iron loss. If it is less than 0.1%, the iron loss is too bad, and the upper limit is 1.5% because if it exceeds this, the magnetic flux density is lowered.

[Mn]: Mn is added in an amount of 0.1% or more in order to increase the hardness of the steel sheet and improve the punchability. The bead width at the time of welding the laminated core becomes wider when Mn is added in an amount of 0.3% or more, and is preferably 0.3% or more (see Japanese Patent Application No. 63-333830). The upper limit of 1.5% is for economic reasons.

[P]: P is also added to increase the hardness of the steel sheet and improve the punchability. When the upper limit of 0.15% is exceeded, embrittlement becomes remarkable.

[S]: S becomes a sulfide such as MnS and deteriorates iron loss, so the content was made 0.008% or less. S is a surface active element,
Since it is limited to 0.008% or less in terms of iron loss, it is considered that the bead width is not affected.

[Sol.Al]: sol.Al is a laminated iron oxide after magnetic annealing that has a composition with a large amount of Al ₂ O _{3 in} the oxide cross-section formed by reacting with oxygen in the annealing atmosphere during magnetic annealing in the slit cross section and punching cross section. Add 0.01% or more to widen the bead width during core welding.
The upper limit is set to 1.0% because if it exceeds this, the magnetic flux density is lowered.

[TN]: N becomes a nitride such as AlN and worsens iron loss, so the TN content is made 0.005% or less.

[TO]: O forms an oxide and worsens iron loss.
The TO amount is 0.02% or less.

[Sol.Al] / [Si]: The oxide film formed by reacting with oxygen in the annealing atmosphere during magnetic annealing on the slit cross section and punching cross section has a composition with a large amount of Al ₂ O _{3 and} is a bead at the time of welding a laminated iron core. To widen the width, [sol.Al] / [Si] ≧ 0.02.

[Al ₂ O ₃ ] / ([SiO ₂ ] + [MnO] + [Al ₂ O ₃ ]) × 100:
In order to suppress the release of oxygen during welding and to widen the bead width during laminated iron core welding after magnetic annealing, the oxide composition in the steel should be such that a large amount of Al ₂ O ₃ is contained in [Al ₂ O ₃ ] / ([SiO ₂ ] + [MnO] + [Al ₂ O ₃ ]) × 100
40% or more.

Average grain size after intermediate annealing: If the average grain size after intermediate annealing is less than 10 μm or exceeds 15 μm, the magnetic flux density in the L direction cannot be increased.

Reduction ratio of second cold rolling: If the reduction ratio of the second cold rolling is less than 3% or exceeds 10%, the magnetic flux density in the L direction cannot be increased.

Surface roughness of the steel sheet after the second cold rolling: When the surface roughness of the steel sheet after the second cold rolling exceeds 15 μ-in. RMS, the magnetic flux density in the L direction cannot be increased.

Hot-rolled sheet annealing temperature: Hot-rolled sheet annealing is performed as necessary,
Below the lower limit of 700 ° C, there is no effect of improving the magnetic properties, and above the upper limit of 1000 ° C, cold ductility deteriorates.

〔Example〕

(Example 1) Slabs for non-oriented electrical steel sheets having various component compositions were manufactured. This was hot rolled and then cold rolled to an intermediate thickness of 0.51 to 0.57 mm, the conditions of intermediate annealing were changed, and the average grain size after intermediate annealing was changed. These were subjected to a second cold rolling with a reduction rate of 1 to 13%, and the roughness of the steel sheet was 13 to 14 μ-in.
The final product plate thickness was 0.50 mm by RMS, and the product was coated with an insulating film. After that, the sample for bead width investigation is 10 ×
It was cut into 30 mm, 60 sheets were laminated to a thickness of 30 mm, and annealed at 750 ° C. for 2 hours. And, TIG welding, welding current 100A, welding speed 65cm / min, tightening pressure 25kgf / cm ² , arc length 2mm,
The welding was performed under the welding conditions of 1.6 mmφ tungsten electrode containing 2% thorium. On the other hand, the magnetic characteristics of the Epstein sample are 750.
Magnetic annealing was performed at ℃ × 2 hours and evaluated. Table 1 shows the component composition, the bead width, the average grain size after the intermediate annealing, the rolling reduction in the second cold rolling, and the magnetic properties at this time.

From this, it is understood that in the case of the present invention example, both the magnetic characteristics and the bead width during welding of the laminated iron core are excellent.

(Example 2) A slab for non-oriented electrical steel sheets having the composition shown in Table 2 was manufactured. This was hot-rolled and hot-rolled sheet was annealed under various conditions.
Then, cold rolling was performed to an intermediate thickness of 0.53 mm, the conditions of the intermediate annealing were changed, and the average crystal grain size after the intermediate annealing was changed. A second cold rolling with a reduction rate of 5% was performed on these, and the roughness of the steel sheet was 13 to 14 μ-in. RMS, and the final product sheet thickness was 0.50 mm. Then, the sample for bead width investigation was cut into 10 × 30 mm, 60 pieces were laminated to a thickness of 30 mm, and annealed at 750 ° C. for 2 hours. And for TIG welding, welding current is 100A, welding speed is 65cm / min, tightening pressure is 25kg.
f / cm ² , arc length 2mm, 2% thorium tungsten 1.6
The welding was performed under the welding conditions of the mmφ electrode. On the other hand, the magnetic characteristics were evaluated by magnetically annealing the Epstein sample at 750 ° C. for 2 hours. Table 2 shows the component composition, the annealing conditions of the hot rolled sheet, the bead width, the average grain size after the intermediate annealing, and the magnetic properties at this time.

From this, it can be seen that when the hot-rolled sheet is annealed at 700 to 1000 ° C, the magnetic properties are more excellent and the bead width at the time of welding the laminated iron core is also excellent.

[Advantages of the Invention] As described above, according to the present invention, it is possible to manufacture a non-oriented electrical steel sheet having excellent magnetic properties after magnetic annealing and having a wide bead width during welding of a laminated core.

[Brief description of drawings]

Fig. 1 shows that EI core plate cutting has a magnetic path ratio of 75 in the rolling direction.
2 and FIG. 2 show that [Al ₂ O ₃ ] / ([SiO
₂ ] + [MnO] + [Al ₂ O ₃ ]), [sol.Al] / [Si], and bead width, and FIG. 3 shows [sol.Al] and [sol.Al].
FIG. 4 is a diagram showing the relationship between Al] / [Si] and the bead width, and FIG. 4 is a diagram showing the relationship between the average grain size after intermediate annealing, the rolling reduction of the second cold rolling, and the magnetic flux density in the L direction, FIG. 5 is a diagram showing the relationship between the Si content, the intermediate annealing conditions, and the average crystal grain size after the intermediate annealing, and FIG. 6 is a diagram showing the relationship between the hot rolled sheet annealing temperature and the magnetic flux density in the L direction. is there.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masakatsu Sumimoto 2-6-3 Otemachi, Chiyoda-ku, Tokyo In-house Nippon Steel Co., Ltd. (56) Reference JP-A-2-179856 (JP, A) Kosho 56-43294 (JP, B2)

Claims (2)

[Claims] 1. [C] 0.015% or less, [Si] 0.1 to 1.5%,
[Mn] 0.1 to 1.5%, [P] 0.15% or less, [S] 0.008%
Below, [sol.Al] 0.01-1.0%, [TN] 0.0050% or less,
Including [TO] 0.02% or less, [sol.Al] / [Si] ≧ 0.0
2, [Al ₂ O ₃ ] / ([SiO ₂ ] + [MnO] + [Al ₂ O ₃ ]) × 100 ≧
When a slab satisfying 40% and having the balance of iron and unavoidable impurities is hot-rolled and then subjected to two cold-rollings with an intermediate annealing, the average crystal grain size after the intermediate annealing is 10 to 15 μm, Two
Semi-process with excellent magnetic properties and weldability, characterized in that the reduction ratio of the cold rolling of the second time is 3 to 10% and the surface roughness of the steel sheet after the second cold rolling is 15 μ-in. RMS or less. Manufacturing method of non-oriented electrical steel sheet. 2. The method for producing a semi-process non-oriented electrical steel sheet having excellent magnetic properties and weldability according to claim 1, wherein the hot rolled sheet is annealed at 700 to 1000 ° C.