JPS58164724A - Production of nondirectionally grain oriented electrical steel plate having excellent mangnetic characteristic - Google Patents

Abstract

PURPOSE:To produce a nondirectionally oriented electrical steel plate having excellent magnetic characteristics by applying a specific heat treatment to a hot rolled steel plate contg. B prior to cold rolling thereby annihilating the suppressing effect for growth of crystal grains by AlN. CONSTITUTION:The silicon steel contg. <0.050% C, <4.0% Si, 0.1-0.5% Mn, <0.1% Al, <0.1% P, <0.02% S and <0.005% N, and in the case of 0.01-0.02% S, contg. 0.003-0.03% at least 1 kind selected among Ca and rare earth elements, and contg. B so as to contain B/N at 0.2-0.5 according to the contents of N is melted. The ingot thereof is hot-rolled and is then annealed for 2-10min at 700-1,000 deg.C, or is subjected to heat treatment for cooling the same quickly upon lapse of 4-30sec when the temp. at the end of the hot rolling is >=750 deg.C, whereafter the ingot is cold-rolled. Crystal grains are grown under suppressed deposition of AlN by B and with the decreased effect for suppressing the crystallization by AlN, whereby a silicon steel plate having excellent magnetic characteristics is produced.

Description

[Detailed Description of the Invention] - This invention relates to - a method for producing a non-oriented magnetic steel sheet with excellent magnetic properties, and particularly aims to enable inexpensive production of this magnetic material with low iron loss. It is something.

There are three types of electrical steel sheets: oriented silicon steel sheets and non-oriented electrical steel sheets. Among these, non-oriented electromagnetic chain plates have a JI! It has a crystalline structure, and S
1 content is also 1 weight from zero (hereinafter simply indicated by an arc T)! covers a wide range.

Non-oriented electrical steel sheets are mainly used for small dust motors, relays, small transformers, stabilizers, etc. because of their small orientation ratio and low price.

2) It is necessary to reduce the iron loss of non-oriented electrical steel sheets in order to avoid such energy loss in electrical equipment. /! l
The eddy current loss is mainly determined by the plate thickness and the 81 content, so metallurgical efforts to lower the core loss are aimed at reducing the 81 loss. In other words, metallurgically, the crystal grains of the steel plate are coarsened to 111! I
The aim is to reduce I loss.

Therefore, it is necessary to modify the grain growth properties of the crystal grains of steel sheets, and Mn111 and 11n8 are known as precipitates in steel that suppress the grain growth of IIl sheets.
．． On the other hand, it is difficult to eliminate the suppressive power of grain growth by reducing the amount of Mu19M for 5IM. For example, for the reduction of Muj, .001% or less, which would lead to a significant increase in price, and also with regard to N.
It is necessary to keep the content below 0.001%, which is impossible with the current kojido technique.

For N content of 40 to 60 ppm, which is the normal N level, a method of adding more than 0.01% Mu 1 has been known for a long time as a means to eliminate the grain growth suppressing power of Mu IM. Even now, most non-oriented silicon III plates are
Manufactured using a method that adds more than 0.1 ml of ml. However, adding a large amount of ml increases the price of the chain.
Therefore, the mu1 content of the undesirable and cheapest steel is usually 0.008 to 0.1%;
In this range, the grain growth suppressing effect of MutN cannot be ignored! be.

As a means to avoid such disadvantages, a method of adding it to BIN is proposed, for example, in Japanese Patent Publication No. 1114-1111910 and Japanese Patent Application Laid-Open No. 65-47110. Here, the weight ratio of 1 to N (written as 87M) is 0. I O-j
The content is 8 in the range of l, 50. This makes it possible to fix N and eliminate the grain growth suppressing effect of MutW, and the B content is balanced with the content of y. It should be determined by There is a limit to the amount, which determines the upper IKB/M-g, sol, and the smaller the ratio of B, the smaller the amount of N fixed as BM, and the greater the amount of IM precipitated, which makes the copper plate The grains become finer, so the lower limit of B is B/)f-0,IO
Below this, it has no effect.

However, the B/N is O, SO ~ 1. When a non-oriented electrical steel sheet is manufactured within the range of fi O, B additive-free 1
It has the disadvantage that the amm variation is lower than that of -ism, and this is because the magnetization rate (111) increases by ism.

That is, as mentioned above, the blade in steel usually has a thickness of 40~＠o
Since it is ppm, B, which corresponds to B/) 10.50-1.60, increases by 0.0010 A-0,0115%,
This is obviously disadvantageous both in terms of making - **T inexpensive and also in terms of not degrading the increased magnetic flux density. So o, o o
g.

It is important for development research*m to eliminate the suppressive force of MU even at a temperature below 0.16 (B/0.16).

Cof) Jl Akira is conducting research with the aim of advantageously eliminating the grain growth inhibition of Mu411 at low B content and achieving non-directional properties with excellent magnetic properties. An advantageous method for easily obtaining a 111m plate has been discovered.

The inventors discovered that, despite the low B content of 2θppm or less, a heat treatment prior to cold-opening rolling produced a suppressive force-dissipating effect system for MuAN, and investigated appropriate thermal field conditions for this purpose. By doing so, this invention was completed. That is, 0: 0.050 weight factor, 8114.0 weight factor or less,
Mn! 0.1-0. ! i weight regret and muj $ 0
．． 10 weight attack or less, p $ 0.1 weight whisper or less, @ s
O, 01 below the heavy weight class, M 0.005 weight below the weight class - 8!0.01 - 0.01 weight class or below
and rare earth elements together with o, oog ~o, osjll-, and BIB/)T is 0.3~O depending on the content.
1s of silicon steel, and after hot rolling the silicon steel by a conventional method, it is possible to form a hot-rolled steel strip with moulds, which are caused by BM preferentially precipitated at high temperatures during hot rolling. Heat treatment is performed after hot rolling to fix the material, and then pickling is carried out by 1FjJ cold rolling or one or more φ cold rolling including intermediate rolling according to the conventional method.

This is a control method for non-oriented electrical steel sheets with excellent magnetic properties, in which the final plate thickness is determined, and then finish annealing is performed. Annealing for 1 minute - 10 hours at a concentration of 1 ml followed by one cold rolling to achieve the final thickness, or 1 x or 6! of hot rolled #T bales. In practical terms, it is preferred that the chain band be self-annealed by the heat retained in the coil itself, which is generated by coiling the chain band at mff of IO° C. or more.

At low B content, the inhibitory power of MuAM is eliminated 7! In order to find conditions under which this can be achieved, the inventors conducted the following experiment.

Experiment I: A steel ingot having the components shown in Figure 1 was manufactured in a laboratory, heated at 1100°C, and then hot rolled to a thickness of 2.6 mm.

In addition, ##la is one in which B is not added, but appm is inextricably present as an impurity. After pickling each hot-rolled plate, cold rolling was performed, and the plate thickness of I・■ To SOO℃
The properties of the bales that were finish annealed in M for 8 minutes were either Bso or 1. Te1(T), Wiin1llb is 4.8!
! -4-JI7W/'9 There was no difference. On the other hand, the heat wh plate of steel @ a - d was heated from 660℃ to 1000℃.
After annealing for 8 minutes up to 60 hours at a temperature of IO- thickness and heated at SOO℃ for 8 minutes
There was a large difference in the properties between a and a after finishing annealing in S. An example of this is shown in Figure 1 with grains with a ratio of a and 0, or grains containing 15 ppH of B compared to #11000 with 8 pp of B have low iron loss, and appropriate heat treatment conditions must be selected. It can be seen that an improvement of 0.lW/19 or more can be expected in the iron loss of T"i'jz'm'o.The heat treatment time is long l!
The improvement in strength is remarkable, so the minimum heat treatment time at which the 1511g& is improved by 0, IW/39 or more compared to the case of using steel ingot a was determined for each temperature and each steel ingot.
Listed in a.

As shown in the Hxi diagram, the hot rolled sheet is
Heat at 0°C for 3 minutes to 10 hours.
Even when l is as low as 5 to Opp irises, it is possible to sufficiently eliminate the crystal grain growth suppressing effect of MulN. Also, if you are willing to spend a long time of 10 hours or more,
Even at a heat treatment temperature of 6i0° C., it is possible that the grain growth suppressing effect of MuIN disappears.

By heat-treating the hot-rolled sheet once before directly cold-rolling it, the Mr content of B can be reduced even though the content is low.
II white, in which the I constant effect (disappearance of the crystal grain growth suppressing effect of IM) effectively appears, can be considered as follows.

B forms a nitride at a higher temperature than mulch. therefore,
Normally, the N, B, and Mulium that reached the 111m state by heating the slab would precipitate mainly in the BM during cooling, and the fine precipitation of 5IN would be small, so there would be no grain growth suppressing effect. In hot rolling, the introduction of working strain and recovery recrystallization are complicated repetitions, so when the amount of B is small, the precipitated BN becomes the majority of the mulH (Mtl)11
Instead, I can no longer move to a fixed position. If the hot-rolled sheet in this state was pickled and cold-rolled, dislocations introduced by processing strain during final annealing would precipitate grains at extremely low temperatures, resulting in a grain growth suppressing effect. become.

On the other hand, if heat treatment is performed as described above prior to cold rolling of a hot-rolled sheet, B IM will re-precipitate at the precipitated interface, and the amount of fine precipitated IM alone will be reduced, thus reducing the amount of B IM.
It is possible to eliminate the grain growth inhibiting effect of MuIN even if the content is just one level.

When winding a coil after hot rolling for 6 years in one place of the hot rolled sheet before cold rolling, it is also possible to obtain a substitute effect by winding at a temperature higher than SSO°C. I was certain that it would not happen. In other words, adjust the coil winding temperature and coil weight to maintain a temperature of at least 5OIIISF1 or 6IO℃ or higher after winding the coil! By doing so, the same effect as the heat treatment of the hot-rolled sheet is obtained, and tL', self-annealing due to the amount of heat retained in the soundboard coil. This is called heat treatment.

Next, hot-rolled coils are usually cooled immediately after hot-rolling in order to improve pickling properties, or the coiling temperature is reduced to 80% by omitting this rapid cooling.
It is possible to raise the temperature to ℃ or higher. The inventors investigated these processes in factory experiments, including the process of raising the end-of-life temperature to 660°C or higher by omitting the above-mentioned quenching@II, in the case of low-grade steel with a high S1 content and low S1 content. However, the heat treatment process for hot-rolled sheets did not reduce the cost of the process as expected.

Another reason is that in the case of such low-grade steel, the manufacturing cost is originally low, so incorporating the heat treatment process increases the cost by 7 tons, and the cost increase due to pickling strengthens, which accounts for a large proportion of the cost. be. Therefore, we proceeded to melt a rope I'll with a thickness of less than Ll % in the laboratory, heated it at Igoo C, and then hot-rolled it to a thickness of 3 sheets. Finished on a board.

At this time, we varied the temperature at the end of hot rolling and the cooling time after finishing hot rolling, and after winding a single coil at a temperature of 660°C or less, we either pickled the hot rolled sheet or removed it. The pickling property was also good, showing the effect of water cooling. After washing, it is cold rolled to a thickness of OoIIOllm and heated at 800℃ for 8 minutes.
The characteristic values of the products that were final annealed in A are blindly shown in relation to the temperature at the end of hot rolling and the time spent in the cooling chamber afterwards.

Figure 8 shows that if the temperature at the end of hot rolling is 70°C or higher and the time until cooling after hot rolling is 4 seconds or more, even if the coil winding temperature is 60°C or lower, B , indicating that the effect of adding . Moreover, such an effect did not appear when the S1 content exceeded 1.5%.

Regarding this behavior, the inventors believe that when the O 81 content is 1.5% or less, the steel undergoes α″rr change →, and at temperatures above 7110°C, some or all of the steel changes. S-iron, which is r-iron, easily precipitates in r-iron, whereas mu-IN has the property of being easily dissolved in r-iron. Therefore, r-iron remains at the end of hot rolling. If so, it is thought that mu-IN will precipitate in the BM precipitated area within the grains as the r→α change occurs. The MuN precipitated around the BM is now stable and does not precipitate at dislocation sites and becomes harmless by annealing after cold-open rolling. Therefore, this treatment eliminates the grain growth suppressing effect of MuN. In order to achieve S-, it is essential that the temperature is s#I4, and therefore, in this specification, the above-mentioned hot rolling end temperature mass is used for cases where the temperature is 81:1.5 or less.
The heat treatment of the hot-rolled sheet also includes water cooling at 0°C or higher for 94 seconds or more.Next, the reason for this component will be described.

If 0 or 0 is mixed into the product, it will have an adverse effect, so unless it is for a special purpose where decarburization is not performed, it is usually decarburized in the final annealing process, but if it exceeds 0 or oss, it will be decarburized. Since it becomes a part, it is less than o, ois.

8i is necessary for the modification of porcelain, but if it exceeds φ and O, Hika is inferior, so 4. 〇- or less.

Mn is set to 0.11 or more because it is hot-rollable baking soda, but ゛o,
If it exceeds 0.1%, the price will be high. ◎ Muj is used for deoxidation, but 0.11 or more is not necessary for this purpose and 0,11 The above will result in an increase in the price of -, so it should be kept at 0.1% or less. ・P is an element that is unavoidably contained, but if it exceeds 0.1%, it will affect grain growth, so it should be kept at 0.1% or less. .

In principle, S must be 0.01% or less in order to not affect the grain growth of the copper plate, so it is 0.011g.
However, if the steel is less than 81 and S, the steel tapped at the factory has a content of 0.01 to 8% O.OS. In this case, it is possible to keep 8 constant and reduce the amount of Mn8 precipitated by adding rare earth elements or Oa, as disclosed in JP-A No. 5151-11S1 O-hanbi WB@I- 1484m1) Presented in each bulletin! ', and therefore the 8 content is 0.0
1-0. (In cases other than I II, substantially 8 <0.01
The rare earth element or Oa is added as an equivalent amount to o,
It is clear that addition of 0.08% to 0.08% has similar effects.

A rare earth element is a metal with an atomic number of 0.0~v1, and one spear has 1011G of 0., and the rest is La.

Recommended mixtures are commercially available at low cost.

In other words, Mitsushi Metal (such as tV of 10 times 0 is added during SS or added during casting).To confirm the amount of addition, analyze the Oe amount and multiply the value by 8. All you have to do is add up the total amount of rare earth.

In summer, as the amount increases, the required B content increases, and BM has a negative effect as a carrier and reaches the weight T.
e No more than ppm.

The appropriate value of B deteriorates depending on the amount of N, but in the case of this invention, the range of Is it almost 4G-I OPPII? 11! Therefore, it is practically soaked at about 8 to seppm ms.

In the present invention, the steel is produced into the above-mentioned portions and made into slabs by continuous casting, or it is made into a steel ingot using a mold and made into a slab by blooming, and then hot-rolled. The feature of this invention is that one step (2) is performed after hot rolling and before cold rolling.The heat treatment conditions that bring about the fixing effect of B in mu IN by heat treating the hot rolled sheet are 11i11! Generally, the heat exposure range is from 3 minutes to 1011 degrees at a temperature of 100 to 1000°C.

However, if the temperature is 650℃ or higher, the same effect can be obtained by long annealing, so it is better than Kotel-dera Torimae! It is also possible to omit the cooling process and heat the hot-rolled coil at a temperature of 6IO℃ or higher, allowing it to cool down to the heat of the coil itself. Adjust the weight of the coil・10
It is necessary to maintain the temperature above ℃ for the SO time or longer.In addition, if the Si content is high and the transformation is below S%, the temperature at the end of hot rolling should be set above 10°C. By applying the coil quenching treatment for 4 seconds or more, the same effect as the above-mentioned heat treatment can be obtained, and it is possible to improve the pickling properties. If the time at 1IIt is 80 seconds or more, the amount of fisted scale increases again and the pickling performance becomes cloudy (which is not preferable), so the time should be up to 80 seconds.The time from the end of hot rolling to the coil quenching treatment After setting @@I) Iljt field for more than 1 second, press tsuOO~ again.
It may not be prudent to carry out a dark reheat treatment at a temperature of 1000° C. for 8 minutes to 10 hours, and it is even more undesirable from the viewpoint of magnetic properties. This is because the later heat treatment ensures that the mu71 is refreshed.
This is because it can be completely fixed to BN and the grain growth suppressing power of AJN can be completely rendered harmless.Hot-rolled sheets that have been heat-treated before cold rolling, such as 0 or more, can be rolled once after pickling. Alternatively, after performing intermediate annealing and rolling to a final thickness of s11 or higher, finish annealing is performed in a converter and refined by vacuum degassing.
11111f) I, l, I, WtJI 1 minute WIIWk (however, I is rust without adding B) molten steel is continuously cast using a continuous casting method, each (mu) e (B) e (0), (D
) Four slabs were prepared, heated to 1110°C in a heating furnace, and then hot-rolled to obtain a hot-rolled plate with a thickness of 1.0.

At this time, after hot rolling, each #A true slab was rolled at a temperature of 680°C without cooling, and the remaining (
B) and (0) slabs were cooled and hot-rolled coils were wound at a temperature of 100°C.

Next, for the (II) coil in winter, heat 4611 was applied at 800° C. for 6 o'clock. Further, regarding the (D) slab of each steel ingot, the hot rolling was completed at 880°C for 1 second and then cooled, and the hot rolled coil was heated at a temperature of 100°C.

This 1.1.1. Each of the steel wires of W (mu), (B), (0)
, (D) were washed with soap, and the coils of 0.0. I
A large-scale specimen of 1180xsso- was taken, which had a plate thickness of O- and was subjected to continuous decarburization finish annealing at a temperature of 770°C for 1 minute. The sample was a bale on which magnetic measurements were taken, and strain relief annealing was performed again at mass O ℃ for 3 hours. The magnetic properties of that part after annealing are shown in Figure 8. ,・: □, 1 Nishiki a@ As is clear from the above writings, the method of this invention makes it possible to obtain a fleshy electromagnetic plate with excellent magnetic properties for the #Ii plate and -strip.

[Brief explanation of the drawing]

Ill■ indicates the value of improving the iron loss of the final product due to the heat sensitivity of the hot-rolled plate, as a relationship between the amount of B and the amount of glass sag required to improve the iron loss and the optimum hot-rolling value. A graph showing the sheet hot rolling conditions, s8- is a graph showing the electrodynamics of 1 when the temperature at the end of -sagi and the time until cooling after the end of hot rolling are changed. Figure 1-1: Heat m & heat @ ft * M tmtn > Fig. 2 cm: Ko x ** a ＼ Glossy M (m/n Fig. 3
)1゜mouth

Claims (1)

[Claims] 1 030.050 weight weight, 8 snowballs, O weight attack or less, Mn! 0.1-0.1 weight and weight 0.
10 weight or less P t O, 1 weight or less, 8S0.
01 weight attack or less, M s O, 00111 (jk#s or less, however, 8t0.01~O, OS weight) Oa and rare earth elements. , o o s ~ O, OS weight, and depending on the summer content, B I B / H is o, s - o 2 g. In particular, after hot rolling the silicon by a conventional method, a heat treatment is performed after the hot rolling to fix the mu 1M due to BH preferentially precipitated at high temperatures during hot rolling.
First, after pickling, one cold rolling or cold rolling of SRA or higher including intermediate rolling according to the conventional method is performed to obtain the final plate thickness, and then final annealing is performed to improve the magnetic properties. Excellent non-directional tastasi method Method 6 of 1 test to achieve the final plate thickness by rolling 1 Description that the heat treatment after hot rolling is self-annealing using the heat retained in the coil itself, which is obtained by winding a copper strip into a coil at a temperature of 660°C or higher. Method 0 4 81 The method described in l, which has a dietary content of 1.111111% or less, is performed after the heat treatment after hot rolling is performed at 750° C. or higher after 4 seconds to 80 seconds have elapsed from the end of hot rolling. Meiji-shoku's method involves rapid cooling and winding the coil.