JPH02305920A - Production of semi-processed non-oriented electrical steel sheet having excellent magnetic characteristic and weldability - Google Patents

Abstract

PURPOSE:To produce the semi-processed non-oriented electrical steel sheet having excellent magnetic characteristics and weldability by subjecting a hot rolled sheet having a specific compsn. consisting of C, Si, Mn, P, S, Al, N, O, and Fe to cold rolling including a specific intermediate annealing. CONSTITUTION:The slab which contains <=0.015% C, 0.1 to 1.5% Si, 0.1 to 1.5% Mn, <=0.15% P, <=0.008% S, 0.01 to 1.0% solAl, <=0.0050% T, N, and <=0.02% T.O, satisfies solAl/Si>=0.02, Al2O3/(SiO2+MnO+Al2O3)X100>=40% and consists of the balance iron and unavoidable impurities is hot rolled. This hot rolled steel sheet is subjected to the annealing of the hot rolled sheet at 700 to 1000 deg.C. The sheet is thereafter subjected to two passes of the cold rolling including the intermediate annealing. The average crystal grain size after the intermediate annealing is adjusted to 10 to 15mum at this time. Further, the 2nd cold rolling is executed at 3 to 10% draft to adjust the surface roughness of the steel sheet after this rolling to <=15mu - inRMS. The semi-processed non-oriented electrical steel sheet which has the excellent magnetic characteristics after the magnetic annealing and has a wide bead width at the time of welding of laminated iron ores is obtd. in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for manufacturing semi-processed non-oriented electrical steel sheets mainly used for small stationary devices.

[Conventional technology]

Non-oriented electrical steel sheets are mainly used for small static devices such as audio equipment and ballasts. As shown in Fig. 1, EI Cocoa, which is an example of a small static device, has 75% of the magnetic path in the rolling direction (hereinafter referred to as the L direction), so the magnetic properties in the L direction are An excellent non-directional type 1 steel plate is required.

The following method has been proposed as a method for manufacturing a steel plate with excellent magnetic properties in the L direction.

In Japanese Patent Publication No. 56-43294, (Si)0, 1
~1.0%, (T, jV) 0. 0 0 7% or less, 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 in between is 2 to 15%, and the roughness of the steel sheet after rolling is 15 μmin. , R, M, S, a method characterized in that it is carried out using rolling rolls having the following properties.

In JP-A-61-119618, [Si] 1.0
% or less, (Aj) 0.4% or less In a manufacturing method in which a slab containing other materials is hot-rolled and then cold-rolled twice with intermediate annealing in between without hot-rolled plate annealing, the intermediate annealing is performed at 675 ° C to 750 ° C.
A method characterized by continuous annealing at °C for 15 seconds to 2 minutes, and second cold rolling at a rolling reduction of 3 to 7%.

On the other hand, the iron core of a small stationary device is clamped after punching steel plates into a predetermined shape and laminating them, and one method for this is welding. For example, an El core is punched into E-type and 1-type, then laminated and annealed at 750°C for about 2 hours. Next, a bobbin wound with copper wire is inserted into the E-shaped stack, and the ■-shaped part is welded to the E-shaped part to form an iron core. Welding of type E and type 1 is usually performed by TIG welding, but at this time, strength is not so required, but ease of forming a bead is a problem. In other words, it is E type even if the torch position accuracy is poor.

■A steel plate with a wide bead so that the mold can be welded is preferred. By the way, it is possible to change the welding conditions such as increasing the welding current, decreasing the welding speed, and widening the bead width.
Problems such as deterioration of static device characteristics due to increased electrode wear, decreased productivity, increased heat input, thermal distortion, etc. occurred, and the weldability after magnetic annealing was not satisfactory with the above conventional technology. .

Conventionally, improvements in the weldability of a laminated core of non-oriented electrical steel sheets having an organic matter-containing film have been proposed in Japanese Patent Publication No. 49-6744 and Japanese Patent Publication No. 19078-1978, but these both involve magnetic annealing. It was before,
No improvement in weldability, ie, increase in bead width, after magnetic annealing in which organic matter in the film is removed has been proposed.

[Problem to be solved by the invention]

The present invention provides a semi-processed non-directional device for small stationary devices that has excellent magnetic properties in the L direction and excellent weldability, which can solve the drawbacks of the conventional technology that could not satisfy both magnetic properties and weldability. The purpose of this invention is to provide a method for manufacturing electromagnetic steel sheets.

[Means to solve the problem]

The gist of the present invention is as follows.

(1) (C) 0.015% or less, [Si] 0.1
~1.5%, (Mn) 0.1-1.5%, CP) 0.
15% or less, (s)o, oos% or less, (soZ, /I
J) 0.01-1.0%, [T. N) 0.0050
% or less, [T. O) Contains 0.02% or less, (sof,
Aj) / (St)≧0.02, (jVz(h) /
((Sift) + (MnO) + (/VzOs)
) x 100 ≧ 40%, and after hot rolling a slab consisting of residual iron and unavoidable impurities, cold rolling is performed twice with intermediate annealing in between, and the average grain size after J intermediate annealing is
0 to 15, and the second cold rolling with a reduction rate of 3 to 10%.
, the surface roughness of the steel plate after cold rolling in the second direction is 15 μmin.
, R, M, S, a method for producing a non-oriented electrical steel sheet using a patented process characterized by the following.

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

The present inventors have worked diligently to develop a method for manufacturing semi-processed non-oriented electrical steel sheets for small stationary devices that have excellent magnetic properties in the L direction and excellent weldability. The newly obtained findings are described below.

First, regarding weldability, the present inventors investigated the weldability of TI after magnetic annealing.
We conducted repeated research to widen the bead width during G welding. As a result, (soZ.AZ) / (St).

(jVzOa) / ((Si(h) + (MnO
) + (Ajz(h))x 1 0 0, C
sol. By limiting At'J to a specific range,
We have newly discovered that the bead width can be made wider. Figure 2 shows the results of an experiment conducted by the inventor. (C)0.003
%, (St) 0.9-1.1%, (Mn) 0.2%,
[P] 0.07%, [S] 0.0022 ~ 0,00
39%, (T.N) 0.0019 ~ 0.0035%
, (T.O) 0, 0 0 7~0.012%, (so
lAj) 0. 0 0 Molten steel containing 1 to 1.3% was produced by changing the deoxidation method, and the composition of oxide inclusions and C
SOI. The ratio of I'J'J/(St) was changed to form a slab. Subsequently, it was hot rolled, cold rolled to a plate thickness of 0.50 mm, continuously annealed, an insulating film was applied, and annealing was performed at 750° C. for 2 hours. And TIG welding uses a welding current of 100A.
, welding speed 65cm/win.

Arc length 2III11. Argon flow rate 54! /min,
Tightening was carried out under the welding conditions of a pressure of 25 kgf/d and an electrode of 1.6 mm diameter of tungsten containing 2% thorium. At this time, (IVzOs) / ((Sing) + (MnO
) + (AhOz) ) X 100 and (sof, 7V
) / (St) and the bead width are shown in Figure 2. From this, (7Vz(h) / ((SiOz) + (
It has been found that when MnO) + (jVzoa))×100≧40% and (sol, jV)/[Si]≧0.02, the bead width becomes stable and becomes wider than 3 squares.

In the experiment shown in Figure 3, (C) 0.002%, [Si] 0.1
0-0.32%, (Mn) 0.2%, CP) 0.07%
, (S) 0.0033-0.0047%, (N)
0.0025-0.0032%, [T. 0) 0.01
1-0.014%, (sof, Aj) 0.001-0
．． Molten steel containing 0.05% was produced. The composition of the oxide inclusions is CM, O's )/((SiOz) + (M
nO) + (jVz03]) X 100 to 47~5
9%, and the value of (solA7)/(St) was changed to create a slab. This was hot rolled, cold rolled to a plate thickness of 0.50 mm, continuously annealed, and an insulating film was applied to produce a product. The subsequent sample preparation, magnetic annealing, and welding conditions were the same as in the experiment shown in FIG. From this, it has become clear that the absolute amount of (sol, Aj) is required to be 0.01% or more.

As described above, we have newly discovered that the composition of the components and oxide inclusions in the steel affect the bead width after magnetic annealing (
Based on this knowledge (the invention has been patented as Japanese Patent Application No. 63-333830).

The above experiment is an experiment using a two-time cold rolling method, but the present inventor also conducted an experiment using a two-time cold rolling method with intermediate annealing, and an experiment in which hot-rolled sheet annealing was performed in addition to this. It was confirmed that the difference in process did not affect the bead width after magnetic annealing.

By the way, in the aforementioned Japanese Patent Publication No. 56-43294, (
Si30.1-1.0%, [T. Aj) O,OO
When cold rolling a hot rolled sheet containing 7% or less with an intermediate annealing in between, the cold rolling rate of the second cold rolling is 2 to 15%, and the roughness of the steel sheet after rolling is 15 μ to in, R , M, S, a method for manufacturing a non-oriented electrical steel sheet with high magnetic flux density in the grain direction has been proposed, which is characterized by using rolling rolls as follows. However, this method [T. 7V) is 0
．． 0.007% or less, and in the specification, aluminum is used in various precipitates.

We imagine that they exist in the form of inclusions, and that they develop unfavorable crystal orientations that lower magnetic permeability during grain growth due to annealing [T. It states that if the content 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 mentioned above, it is essential to contain (sol/1j) at least 0.01% and to have a composition with a high proportion of M2O3 in oxide inclusions. .

Therefore, the present inventor created a composition containing 0.01% or more of (solA7) and a high ratio of M2O as oxide inclusions, resulting in a wide bead width after magnetic annealing and a decrease in the magnetic flux density in the L direction. He worked hard to invent a method for producing highly non-oriented electrical steel sheets.

In the experiment shown in Figure 4, (C) 0.003%, (St) 0.3
4%, (Mn) 0.2%, [P] 0.07%, [
S] 0.0032%, [T. N) 0.0021%,
[T. O) 0.007%, (sof, kl
) 0.26%, (Aj203) /([Si
Og) + (MnO) + (jVto*) ) X
In the process of hot rolling a slab with 51% of 100 and two-time cold rolling with intermediate annealing, the
The steel plate has an intermediate thickness of 13 to 14 mm, is annealed at various intermediate annealing temperatures, and then cold rolled for the second time at a cold rolling rate of 0 to 15%. , S, and
The final product plate thickness was 0.50 mm. And 750°
Magnetic annealing was performed for C×2 hours, and the magnetic properties were evaluated. At this time, the average grain size after intermediate annealing, the second cold rolling rate and L
The relationship between magnetic flux density and direction is shown in FIG. From the experimental example shown in FIG. 4, it can be seen that the magnetic flux density in the L direction becomes high when the intermediate grain size is 10 to 15 m and the second cold rolling ratio of 7 is 3 to 10%. That is, by limiting the intermediate grain size and the second cold rolling rate to narrow ranges, (soj, jV) can be reduced to 0.01.
% or more, we succeeded in increasing the magnetic flux density in the direction. For example, we were able to obtain a magnetic flux density BS6 of 1.82 T or more in the L direction with a steel plate containing 0.60% Si+lJ.

The relationship between the temperature and time of intermediate annealing and the average grain size is as follows:
Although it strictly exists for one material, this relationship becomes deviated when the component materials change. For example, Si
The recrystallization start temperature and grain growth rate vary depending on the content.

An example of an experiment regarding this relationship is shown in FIG. (St)
A hot-rolled sheet made of component materials of three types: 0.1%, 1.0%, and 1.8%, with other elements other than iron being 0.005% or less, is cold-rolled at a reduction rate of 82%, Soaking time for intermediate annealing is 3
The soaking temperature was fixed at 0 seconds, the soaking temperature was changed, and the relationship with the average crystal grain size was investigated. From this, it can be seen that the obtained average crystal grain size differs depending on the Si content even when the soaking time is the same. Therefore, in the present invention, the intermediate annealing conditions are defined by a metallurgically meaningful average grain size.

In the experiment shown in FIG. 6, the hot rolled sheet used in the experiment shown in FIG. 4 was annealed at various temperatures. and 0.52 to 0.56
It was made into an intermediate thickness of mm, and intermediate annealing was performed, and the average crystal grain size after intermediate annealing was set to 121 mm. Then, a second cold rolling is performed with a reduction ratio of 3 to 10%, and the roughness of the steel plate is 1'3 to 10%.
14 II-in, R, M, S, binding, final product board thickness was 0.50 mm. Then, magnetic annealing was performed at 750°C for 2 hours, and the magnetic properties were evaluated.

From the experimental example shown in FIG. 6, it can be seen that when the hot rolled sheet is annealed at 700''C or higher, the magnetic flux density increases by about 100G.

(Relationship with conventionally known technology) In the aforementioned Japanese Patent Publication No. 56-43294, (St) 0
．． 1-1.0%, [T. A7) In a production method in which a hot rolled sheet containing 7% or less of O, OO is cold rolled twice with an intermediate annealing in between, the cold rolling rate of the second cold rolling is 2 to 15%, and the roughness of the steel sheet after rolling is A method has been proposed which is characterized in that the rolling process is carried out using a rolling roll having the following properties: 15 μmin, R, 11, S, or less.

However, with this technology, the upper limit of (TJJ) is 0.007%
Therefore, the bead width during welding after magnetic annealing becomes narrow.

On the other hand, the present invention contains (sojJJ) at 0.01% or more, (sol/V) / (St), (Al
zOs) /((SiOz) + (MnO) + (
/'JzOs) ) By controlling X 100 within a narrow range, excellent weldability is exhibited, and the average grain size after intermediate annealing and the rolling reduction ratio during the second cold rolling are limited within a narrow range. This technology succeeded in obtaining excellent magnetic properties even when containing 0.01% or more of (so7.AI), and is a technique that satisfies both the magnetic properties and weldability after magnetic annealing. Therefore, the present invention is understood to be a completely different technology from the technology described in Japanese Patent Publication No. 56-43294.

In JP-A-61-119618, (Si20.0
% or less, (/V) 0.4% or less In a manufacturing method in which a slab containing other components is hot-rolled and then cold-rolled twice with intermediate annealing in between without hot-rolled sheet annealing, the intermediate annealing is performed at 675 to 750 °C.
A method has been proposed in which continuous annealing is carried out for 15 seconds to 2 minutes, and the second cold rolling is carried out at a rolling reduction of 3 to 7%. However, in this technique, there is no description of weldability after magnetic annealing, and there is no idea of limiting the range of components and oxide inclusions in the steel. The roughness of the steel plate is 15μmin, R, M, S
, the following is essential to increase the magnetic flux density in the L direction, but there is no description of the concept and it is understood that this is a completely different technology from the present invention.

[Reasons for limiting configuration requirements]

(C): If C exceeds 0.015%, it will not only be harmful to the magnetic properties but also cause significant magnetic aging due to the precipitation of C, deteriorating the magnetic properties.
o, oio% or less.

[Si]: Si is an element that reduces iron loss.

If it is less than 0.1%, the iron loss will be too bad, and the reason why the upper limit is set at 1.5% is because if it exceeds this, the magnetic flux density will decrease.

(Mn): Mn is added in an amount of 0.11% or more to increase the hardness of the steel sheet and improve punchability. The bead width during laminated core welding becomes wider when 0.3% or more of Mn is added, so it 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 punching properties. If the upper limit of 0.15% is exceeded, embrittlement will be significant.

[S]: S becomes a sulfide such as MnS and worsens iron loss, so the content was set to 0.0 s% or less. Although S is a surface-active element, it is limited to 0.008% or less in view of iron loss, so it is thought that it does not affect the bead width.

[sol, IJ): sat, jV has an oxide film that is generated on the slit cross section and punched cross section by reacting with oxygen in the annealing atmosphere during magnetic annealing, and has a composition rich in M2O3, and when welding the laminated iron core after magnetic annealing. It is added in an amount of 0.01% or more to widen the dot width. The reason why the upper limit is set to 1.0% is that exceeding this value causes a decrease in magnetic flux density.

[T. N): Since N becomes a nitride such as 7VN and worsens iron loss, the amounts of T and N are set to 5% or less of O and OO.

[T. O): Since O forms an oxide and worsens iron loss, the amounts of T and O are set to 0.02% or less.

(soljlJ) / (St) The oxide film that is generated by reacting with oxygen in the annealing atmosphere during magnetic annealing on the Nislit cross section and punched cross section has a composition rich in U and O, and the bead width during laminated iron core welding is widened. In order to (soj, V]/
(St)≧0.02.

CI'JzQz) / ((SiOz) + (MnO
) + (AJgOi) ) , (Ajz(1+) / ((Stow) +
(MnO) + (A1z03) )X100 by 40%
The above shall apply.

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

Reduction ratio of second cold rolling: If the reduction ratio of 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 plate after the second cold rolling: The surface roughness of the steel plate after the second cold rolling is 15 μmin.

If R, M, and S are exceeded, the magnetic flux density in the L direction cannot be increased.

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

〔Example〕

(Example 1) Slabs for non-oriented electrical steel sheets having various compositions were manufactured. This was hot rolled and then cold rolled to 0.51 to 0.57
The intermediate thickness was set to wn, 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 rolling reduction of 1 to 13%, and the roughness of the steel plate was 1.
3-14 g-in, R,M,'S.

The final product was made to have a thickness of 0.50+nm, and an insulating film was applied to produce a product. After that, the sample for bead width investigation was 1
Cut to 10x30a, stack 60 sheets to 30mm thickness, 7
Annealing was performed at 50'CX for 2 hours. And T I
For G'f4 contact, welding current 100A, welding speed 65cm
/min, tightening pressure is 25 kgfloor, arc length 2mm, tungsten with 2% thorium 1.6 diameter
This was carried out under the welding conditions of the electrode. On the other hand, the magnetic properties were evaluated by magnetically annealing the Epstein sample at 750'CX for 2 hours. Table 1 shows the component composition, bead width, average grain size after intermediate annealing, rolling reduction of the second cold rolling, and magnetic properties at this time.

This shows that in the case of the example of the present invention, both the magnetic properties and the bead width during laminated core welding are excellent.

(Example 2) A slab for a non-oriented electrical steel sheet having the composition shown in Table 2 was manufactured. This was hot-rolled and hot-rolled sheets were annealed under various conditions.

Subsequently, the material was cold rolled to an intermediate thickness of 0.53 mm, and the intermediate annealing conditions were changed to change the average grain size after the intermediate annealing. These were subjected to a second cold rolling at a reduction rate of 5%, and the roughness of the steel plate was 13 to 14 tl-in, R, M, S.
, the final product plate thickness was set to 0.50 mm, and an insulating film was applied to produce a product. After that, the sample for bead width investigation was 1
Cut to 010x30, stack 60 sheets to 30mm thickness, 7
Annealing was performed at 50°C for 2 hours. TIC welding requires a welding current of 100A and a welding speed of 55 cm/min.
Tightening was carried out under the following welding conditions: a pressure of 25) cgf/d, an arc length of 2 mm, and a 1.6 mm diameter tungsten electrode containing 2% thorium.

On the other hand, the magnetic properties of the Epstein sample were measured at 750°C x 2
Magnetic annealing for hours was performed and evaluated. At this time, the component composition, hot rolled sheet annealing conditions, bead width, average grain size after intermediate annealing,
The magnetic properties are shown in Table 2.

From this, it can be seen that when the hot rolled sheet is annealed at 700 to 1000'C, the magnetic properties are better and the bead width during laminated core welding is also better.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to manufacture a magnetic steel sheet which has excellent magnetic properties after magnetic annealing and has a non-directional welding width with a wide bead width during laminated core welding.

[Brief explanation of drawings]

Figure 1 is a diagram showing that the ratio of the rolling direction in the planing of the El core is 75% of the magnetic path, and Figure 2 is a diagram showing that (Ajz (h)
/ ((St(h) + (MnO) + (A7z
Figure 3 shows the relationship between (soZ, AJ: l and (solJJ) / (St) and bead width. Figure 4 shows 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, and Figure 5 shows the relationship between the St content and intermediate annealing conditions. Figure 6 is a diagram showing the relationship between hot-rolled sheet annealing temperature and magnetic flux density in the L direction. Figure 2 - Explosion fan y Go Figure 4 ψ 藺黓KYU /) Meyanagi Figure 5 Temperature of the fire gun (v) Figure 6 Shikou [琵y＃L (τ)

Claims (2)

[Claims] (1) [C] 0.015% or less, [Si] 0.1-1.
5%, [Mn] 0.1-1.5%, [P] 0.15% or less, [S] 0.008% or less, [sol. Al〕0.0
1-1.0%, [T. N] 0.0050% or less, [T.
O] 0.02% or less, [sol. Al]/[Si
]≧0.02, [Al_2O_3]/([SiO_2]
+ [MnO] + [Al_2O_3])×100≧40%
When hot-rolling a slab that satisfies the following and consists of residual iron and unavoidable impurities, and then cold-rolling it twice with intermediate annealing in between, the average grain size after intermediate annealing is 10 to 15 μm, and 2
The reduction rate of the second cold rolling was 3 to 10%, and the surface roughness of the steel plate after the second cold rolling was 15μ-in. R. M. S. A method for producing a semi-processed non-oriented electrical steel sheet with excellent magnetic properties and weldability, characterized by the following: (2) The method for producing a semi-processed non-oriented electrical steel sheet with excellent magnetic properties and weldability according to claim 1, characterized in that the hot-rolled sheet is annealed at 700 to 1000°C.