JPS6389622A - Production of grain oriented high-si silicon steel sheet - Google Patents

Abstract

PURPOSE:To produce a grain oriented high-Si silicon steel sheet having excellent cold workability by subjected a silicon steel having the specific compsn. consisting of C, Si, Al, Ti, V and Fe to specific hot rolling, warm rolling and cold rolling including intermediate annealing. CONSTITUTION:The steel having the compsn. contg. 0.02-0.08wt% C, 4.0-6.5% Si, and 0.002-0.02% solAl, and further, contg. at least one kind of 0.02-0.10% Ti, and 0.02-0.10% V, and the balance incidental impurities and Fe is heated to 1,250-1,150 deg.C and is hot rolled. The hot rolled sheet is then subjected to the warm rolling at 700-550 deg.C and at least at 20%, more preferably about 40-70% draft. The rolled sheet is thereafter subjected to a 1st time of the cold rolling in a 50-70% draft range and further to a 2nd time of the cold rolling including the intermediate annealing at 750-850 deg.C to preferably about <=0.2mm thickness. The grain oriented high-Si silicon steel sheet which has the good magnetic characteristics and is free from edge cracking is thereby obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for manufacturing a high-silicon steel sheet containing 4.0 to 6.5% Si and having excellent cold workability.

(Prior art) Silicon steel sheets containing a large amount of Si are known to exhibit excellent magnetic properties as so-called electrical steel sheets, such as low core loss and low magnetostriction. If the silicon steel sheet exceeds 4%, the cold workability deteriorates significantly, so the production of silicon steel sheets exceeding 4.0% has not been put to practical use.On the other hand, for stone sheets, steel sheets are processed before cold rolling. It has been reported that cold workability is improved by rolling near the recrystallization temperature (Journal of the Japan Institute of Metals vol.
.

30.1966, p. 562), and that it is possible to directly produce a ribbon by rapidly solidifying a molten metal, as disclosed in JP-A-55-69223 and JP-A-60-32705.
Disclosed in the issue. The rapid solidification method has the advantage of being able to produce thin strips directly from molten steel, so it can omit various rolling processes. It has drawbacks such as difficulty in controlling the texture and difficulty in manufacturing wide-width products. In addition, it also contains 4 to 10% of 5ir in terms of composition, Al: 2% or less, gate n: 2% or less, Co: 10%
The following discloses a product containing at least one type of Ni: 3% or less, and a total of 0.1% or less of unavoidable impurities such as C, N, and OlS, but these are assumed to be rapidly solidified. Magnetic properties are evaluated. On the other hand, the rolling method is effective as a method for mass-producing wide-width products, but there is a big gap in the application of Ishiban et al.'s method alone to industrial-scale production. . In particular, it is assembled and
In order to improve the magnetic properties by controlling the 11 weave, it is also necessary to overcome the problem of cracking during cold rolling after intermediate annealing.

(Means for Solving the Problems) In view of the current situation, the inventors conducted a detailed study on the relationship between the cold workability of silicon aiiFi, the warm rolling method, and the component composition. As a result, the warm rolling process near the recrystallization temperature aims to refine the crystal grains and introduce mobile dislocations, which suppresses the generation of twins during cold rolling. It was revealed that the workability could be improved, and for this purpose, dispersing precipitated particles of TiC, VC, etc. into the steel would lead to grain refinement based on grain growth suppression and dislocation caused by the precipitated particles. It has been found that this method significantly improves cold workability. Furthermore, it has been found that these fine precipitate particles suppress grain growth during intermediate annealing after the first cold rolling, and thus improve workability during the second cold rolling, and the present invention has now been completed.

That is, in the present invention, in weight percent, C: 0.02 to 0.08%, Si: 4°0 to 6.5%.
, sol, Al: 0.002-0.02%, further Ti: 0.02-0.10% and v: o, o2-
A steel having a composition of at least one of o, to%, the balance incidental impurities, and re is heated to 1250-1150°C and hot rolled, and then at least 20% at 700-550°C.
Warm rolling is performed at a rolling reduction of 50% to 70%, followed by a second cold rolling with an intermediate annealing at 750 to 850°C. This is a method for producing a unidirectional high-Si silicon steel sheet that is characterized by excellent cold workability.

(Sakugetsu) Next, the reason for limiting the steel composition and others as described above in the present invention will be corrected as follows.

C is added to deoxidize and form carbides of Ti or V, and 0.02% or more is required for sufficient carbide formation, but if it exceeds 0.08%, the magnetic properties will deteriorate; The decarburization process takes longer.

“If Si is less than 4.0%, such deterioration of cold workability will not be a problem, and if it exceeds 6.5%, cracking during cold rolling will not be completely prevented even in the present invention. It cannot be removed.

Al is added for deoxidation, and for this purpose so
1, Al 0.002% or more is required, but if it exceeds 0.02% it will be harmful to the magnetic properties.

Ti and V are added to improve cold workability due to precipitation of carbides, and for this purpose, each should be added at 0.02%.
However, if it exceeds 0.10%, the density of precipitated particles will increase, which will actually deteriorate cold workability.

In order to uniformly disperse Ti and V carbides in the steel with a suitable density, according to the present invention, 1150-1250
℃ to decompose and dissolve Tic and V(, into solid solution), followed by hot rolling at 700 to 550° C. with a rolling reduction of 20% or more.

If the warm rolling conditions are outside the above range, the amount of Ti and V carbides precipitated will not be sufficient or will precipitate excessively, making it impossible to achieve the object of the present invention. Preferably, in the warm rolling in the present invention, the rolling temperature is 700 to 550.
Temperature near the recrystallization temperature within the range of °C, reduction rate of 40 to 7
It is 0% rolling, and its details are not particularly specified.

Cold rolling is performed to obtain a (110) (001) recrystallized Mi weave, and if it is outside the range of 50 to 70%, a (110) (001) recrystallized Mi weave will not be obtained and magnetic Characteristics do not improve. This two-time cold rolling method including intermediate annealing is a well-known method for 3% Si silicon steel.
(110) (00
1] A unidirectional silicon steel plate with a uniform grain size of 110 (001) is manufactured using secondary recrystallization. However, it is not easy to use inhibitors for high-Si steel, but if you take advantage of the small surface energy of the (110) plane of iron in vacuum or soft hydrogen, you can obtain it by cold rolling twice.
0) (001) (110) of primary recrystallization texture
(110) (001) by the surface energy method in which (001) oriented grains grow by eroding other grains.
A secondary recrystallized texture can be obtained. For this purpose, it is desirable that the plate thickness be 0,:'+m or less, and the annealing temperature must also be 1150°C or higher. When the plate thickness is more than 0.2 ms, it is difficult to produce penetrating grains that penetrate the plate thickness even at high temperatures of 1150° C. or higher, making secondary recrystallization by the surface energy method difficult. A high vacuum of 10-' torr or higher is required, and if dry hydrogen is used, the dew point must be kept below -10°C or the surface will oxidize (100°C or higher).
) The surface energy of crystal grains in the in-plane direction decreases110)
Growth of crystal grains in the plane direction is inhibited.

The present invention will be explained in more detail by way of examples.

Example 1 Based on silicon steel as shown in Table 1, Tj, ■, Cff
Various variations of 1 were melted into steel ingots with a width of 700IllI and a plate thickness of 50IIIm. This was heated to 1200° C., and if the finishing temperature was lower than 700° C., it was reheated and finished to a plate thickness of 5II. This steel plate was heated to 700°C, and if the rolling finish temperature was below 400°C, it was reheated to perform warm rolling to a plate thickness of 2a+m. After removing rolling scale by pickling this rolled plate in an aqueous sulfuric acid solution, the first cold rolling was performed at a rolling reduction rate of 60%, and the rolling plate was heated to
Intermediate annealing for 1 minute, followed by second cold rolling at a reduction rate of 6
0%, the average depth of edge cracks occurring at both ends of the plate was measured, and this value was used to evaluate cold workability.

These results are summarized in graphs in FIGS. 1 to 6. It was confirmed that the cold workability was significantly excellent with the contents of Ti, V, and C defined by the present invention.

FIGS. 1 and 2 are graphs showing the effects of Ti, C, v, and C on cold workability, respectively, for Steel A (4.5% Si).

Figures 3 and 4 are for steel B (5,5% Si), and Figures 5 and 6 are for steel C (6,5% Si).
) is a graph showing the results of cold workability for each.

In the figures, O indicates no edge cracking, × indicates edge cracking of 5 mm or more at maximum, and Δ indicates an intermediate case.

Example 2 Example 1 was then repeated for steel D-F having a composition within the scope of the present invention as shown in Table 2. However, in this example, the first cold rolling was performed at a reduction rate of 60%, the intermediate temperature was 800°C for 5 minutes, and the second cold rolling was performed at a reduction rate of 55% with a thickness of 0.2 ms.
After rolling to 850℃X in wet hydrogen with dew point of 10℃
5 x 10-' following decarburization annealing of 5a+in
Vacuum annealing at 1200°C x 3H in a torr vacuum,
Its magnetic properties were measured.

The results are shown in Table 3. As shown in Table 3, the high-Si silicon steel sheet according to the present invention has good magnetic properties. As can be seen from the results shown in section 2, the high density (110) (00
1) Development of secondary recrystallized texture is observed.

Table 3 Magnetic properties Example 2 was repeated for Steel F in Table 2.

However, in this case, the degree of dispersion of TiC and VC was varied by changing the heating temperature and warm rolling conditions prior to hot rolling, and the effects thereof were evaluated. The results are summarized in Table 4.

Table 4

[Brief explanation of the drawing]

Figures 1 to 6 are graphs showing cold workability in relation to Tr, V and C contents when the silicon content is varied; and Figure 7 is a graph showing the cold workability of steel E of Example 2. The first (200) pole figure of
Figure 2■ (wt%)! Figure a Ti (1,114%) Figure 4 Calt da) Figure 5 Figure 6 ■ (Tana 2) Figure 7

Claims (1)

[Claims] In weight%, C: 0.02 to 0.08%, Si: 4.0 to 6.5%,
sol, Al: 0.002-0.02%, further Ti: 0.02-0.10% and V: 0.02-0
．． A steel having a composition of 10% of at least one kind, the balance of accompanying impurities and Fe is heated to 1250 to 1150°C and hot rolled, then warm rolled at 700 to 550°C with a reduction rate of at least 20%, and then Unidirectional high-Si silicon, characterized in that the first cold rolling is performed at a reduction rate of 50 to 70%, and the second cold rolling is performed after intermediate annealing at 750 to 850°C. Method of manufacturing steel plates.