JPS5974257A - Nondirectional silicon steel plate with small iron loss - Google Patents

Abstract

PURPOSE:To obtain a nondirectional silicon steel plate with a remarkably reduced iron loss value by restricting the amounts of S, O and N and the total amount of Ti, Zr, Ce and Ca among the impurities in a low C steel plate contg. specified amounts of Si, Al and Mn. CONSTITUTION:The amounts of impurity elements contained in a steel consisting of, by weight, <=0.005% C, 2.5-4.0% Si, 0.25-1.0% Al, 0.1-1.0% Mn and the balance essentially Fe are restricted to <=15ppm S, <=20ppm O, <=25ppm N and <=150ppm Ti+Zr+Ce+Ca. The regulated steel is rolled and annealed. The resulting nondirectional silicon steel plate shows a very small iron loss value and superior magnetic characteristics.

Description

[Detailed Description of the Invention] The present invention relates to a non-oriented silicon steel sheet with low core loss, and in particular reduces the content of other impurity elements Ti, Zr, Oe, and Oa in addition to reducing the S, N, and O contents. We propose a non-oriented silicon steel sheet that exhibits an extremely low iron loss value and is made by controlling the iron loss to a lower value.

Non-oriented silicon steel sheets are mainly used as core materials for motor stators and rotors, hydroelectric generator stators, fluorescent lamp ballasts, and the like. In recent years, due to the rise in energy costs, there has been a strong desire to develop low core loss materials for these devices, especially in the case of large rotating machines, as it is necessary to suppress power loss.

A conventionally known method for improving the iron loss of a non-oriented silicon steel plate is to increase the electrical resistance of the steel plate by increasing the amount of Si or A/l added. However, when it is desired to improve the total iron loss further than the current level, increasing the amount of these components added will deteriorate the cold compaction properties, increase the material cost, and further increase the saturation magnetic flux. Since it causes a decrease in density, there is a limit naturally. In addition, In is added to non-oriented silicon steel sheets as a secondary additive to improve hot workability, but Kn has a small iron loss reduction effect, so a large amount of Kn is added. On the contrary, it deteriorates the magnetic properties, which is undesirable.

For these reasons, at the conventional technical level, 0.855
In the iron loss of a steel plate of m, in the low magnetic field H, b iron loss"to
/so 0.90~Q, 95"7kg, iron loss in high magnetic field"15150 L15~g, 25 W/k
g is the limit, and it has been difficult to stably produce materials equivalent to grade 87, for example. In addition, here, the material equivalent to grade 87 is:
Iron loss W15150 at 50Hz -1.5 Tesla is 2.00W/4G9 or less at product thickness 0.35m71+,
Refers to a product with a thickness of 0.5111111 and an iron loss value of 2.50wAcy or less.

After considering the above points, the present inventors focused on the fact that impurities contained in steel have a strong influence on iron loss, and by suppressing these impurities, the limitations of the conventional technology described above can be overcome. We have overcome this problem and have succeeded in obtaining a non-oriented silicon steel sheet that exhibits an extremely low iron loss value equivalent to class 87.

Therefore, in order to first investigate the influence of impurities on iron loss, the contents of G, S+'0, and N were changed, and 8.
Steel whose composition was adjusted to 2% Soil, 0.60% Al, and 0.20% In was tapped, and a non-oriented silicon steel plate with a thickness of 0.35 mm was manufactured by a conventional method. As a result, C is 0.00
If it is 5% or less, the effect on iron loss is small, but
As for S, O, and N, as is clear from FIG. 1, it was found that they all had extremely large effects on iron loss. First, regarding S,0, it can be seen that reducing the content is effective in improving iron loss. Regarding this point, conventionally, Japanese Patent Publication No. 56-22931 and Japanese Patent Application Laid-Open No. 53-66816
It has already been disclosed as No. 0.
It has also been proposed to regulate ``i'' to 25 ppm or less and S ``i 50 ppm or less (desirably, ao ppm or less). Furthermore, regarding the N content, s o pp
There are reports that it is desirable to limit the amount to less than m.

However, in these known reports and examples, taking the S content as an example, it is 20 to 30 ppm''t's, and the influence on iron loss at even lower S and 0.N levels is not considered. According to Figure 1, S: 15 ppm, 0: 20 ppm, N
: 25 ppm Tfl, the reduction of these impurity-containing lids directly leads to the iron loss reduction effect, S = 15
ppm, O=20 ppm, N=2
51) The iron loss value in the region of I) m is W10150 #”9
a1w15150 #2.20, that is, equivalent to grade 88, was obtained. However, below this, S, O
, Even if the Ni was lowered, the iron loss did not decrease as much as expected.
In the end, W10150≦0.85, W,,15o(2,0
0, that is, it was not possible to obtain an iron loss material equivalent to S7.

Therefore, the present inventors further investigated other impurities, namely G,
P, B, Ti, Oe, (3a,
The influence of Zr content was investigated. Therefore, the content of each of these impurities was systematically changed.Si: a, 2a
%, Al: 0.60%, Mn: 0.20%. A sample steel ingot containing # is made, and the steel plate thickness is 0.35% by a conventional method.
We fabricated our non-oriented silicon steel plate and measured its iron loss value. As a result, for C, as mentioned above, 0.005
% or less, it had no effect on iron loss, and P had no effect at a normal content of o, ooa to 0.1%. Regarding B, o, ooo, which is normally contained in steel,
It was found that around a% it has no effect on iron loss at all. However, the results are different for Ti, Zr, Ce and Ca! II was shown.

That is, as shown in FIG. 2, S≦15 ppfl+
.

0 (20 ppm, in the region containing S, O, N' of N≦25 ppm, such Ti + Zr + Oe +
It was found that the amount of Oa (+l) is closely related to U core loss and has a linear proportional relationship.However, as can be seen from Figure 2, in this region of extremely low S, O, and N, , Ti, Zr, Ce, Oa total is 150
If the content is large, ppm or more, S, 0. The iron loss no longer depends on the H content; for example, even if S, O, and N are lowered to even lower levels, it shows a plateauing phenomenon and does not continue to decrease beyond that level. On the contrary, Ti, zr, ce,
It was found that the above-mentioned linear proportional relationship was restored by suppressing the total amount of ca to 150 ppm or less. In other words, if the S, O, and N contents are further reduced in this impurity-containing lid region, the iron loss will be proportionally reduced to 1°W101.
50 = 0.82, equivalent to class 87 such as W1515G-1.96, making it possible to obtain a material with an extremely low iron loss value.

According to the findings of the present inventors, the reason why such a phenomenon occurs is that in regions with high contents of S, O, and H, the adverse effects of these impurities are not obvious.
The influence of Oe and Oa is a harmful component of S.

It is thought that this phenomenon became apparent due to the removal of 0 and H, resulting in the results shown in Figure 2. This can be understood from Fig. 1, and the materials shown in Fig. 1 are all Ti.
, Zr, Ce, Oa total is 150ppm
Even if S, O, and N were lowered, it was not possible to obtain an iron loss equivalent to class 37.

Note that Ti in the above impurities, 7. r is an impurity mixed in from the refractory in contact with molten steel, and ce and Qa are components that may be added to control the form of sulfides. However, the effects of these components on iron loss have not been clarified until now. For example, T1. The influence of zr on non-oriented silicon steel sheets is generally investigated from the viewpoint of surface shape such as ridging, and in connection with iron loss, as in the present invention, S, O
, H content is extremely low, and there are no reports that have been related to the iron loss of non-oriented silicon steel sheets.

Regarding ae+ca, it has been reported that it is necessary to retain a certain amount or more of S in order to control the form of sulfide in order to improve iron loss in materials with increased amounts of S. There is no report that the relationship with residual ae or Oa has become a problem at extremely low 3 content of 15 ppm or less as in the present invention.

As explained above, the present inventors have discovered that S (15 ppm, O≦20 ppm, N≦251) 1 remains as an impurity.
) m is extremely small, and under the condition that this is achieved, at the same time other impurities such as Ti, Zr
It was newly discovered that a non-oriented silicon steel sheet exhibiting an extremely low iron loss value can be corroded if the two points of 150 ppm or less are achieved, in which the sum of Oe, Oa, and Oa are 150 ppm or less.

The above-mentioned non-oriented silicon steel sheet of the present invention may be produced by a conventional conventional method except for adjusting the composition. In other words, the molten steel that has been blown is degassed and mixed into a predetermined composition, then it is made into an ingot by ingot formation and then bloomed into a slab, or it is made into a slab by continuous casting and then hot rolled. After that, the product is made into a product through a single or two-step cold rolling process in which intermediately fired pure gold is sandwiched.

Next, the range of the component composition of the present invention will be described.

If the CN amount exceeds 0.005% by weight, aging will occur and the properties will deteriorate, so the CN content is set to 0.005% by weight or less.

If the Si weight exceeds 4.0% by weight, cold rollability deteriorates, so the Si weight is limited to 4.0% by weight or less. In addition, if it is less than 2.5% by weight, the electrical resistance will be low and the iron loss will increase, which will deviate from the purpose of the present invention, which is to provide a low iron loss silicon steel sheet, so 2.5% by weight is the lower limit.

A! Like Si, heavy lid% is effective in increasing electrical resistance and lowering iron loss, but if it exceeds 1.0% by weight, 81 type cold workability deteriorates, and if it is less than 0.25% by weight, iron Since the loss is significantly deteriorated, the amount is increased from 0.25% by weight to 1.0% by weight.

The Mn weight must be 0.1% by weight or more from the viewpoint of hot workability, but if it exceeds 1.0% by weight, the magnetism will deteriorate, so it should be from 0.1% to 1.0% by weight. do.

The content of the following impurities to be included in the steel adjusted to the above composition is S<151)Pm, O≦201)Pm
, N (at 25 ppm, and Ti, + zr + a
It is necessary to satisfy e + ca≦150 pI)m, and by adopting such a component composition, it is possible to obtain the non-oriented silicon steel sheet of the present invention exhibiting an extremely low iron loss value.

Example: After blowing in a converter, degassing treatment was performed, and then si:
8.2%, AJ: 0.60%, Mn: 0.2
The molten steel, which was adjusted by adding alloying components with the aim of achieving 0%, was made into a slab by continuous casting. At this time, the deoxidation treatment and desulfurization treatment are performed using a desulfurization flux that uses Oa or a mixture of REM (approximately 50% rare earth element Oe) in the desulfurization flux, and by changing the deoxidation and desulfurization conditions. , S and 0, and the degree of oxidation and nitridation caused by the atmosphere during casting If'kThe degree of Ar sealing t-
By changing the amount of 0 and H, the amount of 0 and H was controlled. Oa and ae
The amount of Q was controlled by changing the S content of the hot metal and the amount of Ca, flux, and REM applied. Also T1
The amount of zrO and zrO depends on the composition of the refractory and
The contents of Ti and Zr, which are impurity components in the ferrosilicon added for i addition, were controlled by using different amounts of Ti and Zr. As a result, a slab having the components shown in Table 1 was obtained. These slabs were heated at 1200°C, then hot-rolled into coils with a thickness of 2.0mm, pickled and divided into two parts, one of which was continuously annealed at 950°C for 3 minutes and then rolled into a coil with a thickness of 2.0mm.
The plate was cold rolled to a thickness of 0.0 mm and subjected to continuous finish annealing for 3 minutes at 980" OX, and then magnetic measurements were performed (one-time cold rolling method). The other one was cold rolled to a thickness of 0.70 mm. The board thickness is 9
After intermediate continuous annealing at 50°C for 3 minutes, the plate was further cold rolled to a thickness of 0.35M and subjected to continuous finish annealing at 980"C for 3 minutes, and then magnetic measurements were performed (cold rolling two-step method). ).

Table 1 shows the results of measuring the magnetic properties of the steel sheets manufactured as described above.

In Table 1, symbols A and B are steels prepared within the impurity content range according to the present invention, and the steel plate has a thickness of 0.85m1M, and the iron loss value is 10150 < O40, Wlr,
150≦2.00, showing extremely good characteristics.

On the other hand, the code 0. shown as a comparative example. Steel plates D and E have high 06, Ti, and Oa, respectively, so the total of Ti, Zr, Oe, and Oa is 150.
pI)m exceeds -1, and the iron loss is inferior to that of the present invention. Also, the symbol F, which is also shown as a comparative example,
Steel plates G and H have S, O, and N values that are outside the range of the present invention, respectively, and it is clear that the iron loss is inferior to that of the present invention.

As explained below, in the steel plate of the present invention, S10.
By adjusting the amount of each impurity element represented by the sum of N7z and Ti + Zr + Ce + Ca to be within a predetermined range, a non-oriented silicon steel sheet with iron loss characteristics significantly exceeding conventional levels can be obtained.

[Brief explanation of the drawing]

Figure 1 shows plate thickness 0.35+1131, Si 3.2%,
This is a graph showing the relationship between S. 0, N content and iron loss for a non-oriented silicon steel plate with Mn (L, 2%, AA O, 6%). , si 3.2%, M
For n0.2%, A#0.6% non-oriented silicon steel plate, S. 0, N content, Ti + Zr + Oe + (Ea
It is a graph showing the relationship between contained graves and iron loss. Figure 1 0---5% (θ≦20ppm, N≦25ppm Δ-0
% (S≦15ppm, N≦25ppm) Figure 2

Claims (1)

[Claims] 1% by weight, mainly O: 0.005% or less, si
+2.5~4.0%, AN: 0.25~1.0
%, Mn: 0.1 to 1.0% and the remainder is substantially Fe, and the impurity elements mixed in are S≦15 ppm and Q≦20 ppm. A non-oriented silicon steel sheet with low iron loss, characterized in that N<25 pI)m and Ti+Zr+Oe+Ca (150 ppm).