JPS6319257B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention contains 2-8% Si and has <100
The present invention relates to a method for manufacturing a (100) in-plane non-oriented silicon steel ribbon in which a crystal structure in which the axes are accumulated in the normal direction of the plate is formed during solidification. Silicon steel sheets containing approximately 3% Si have excellent soft magnetic properties and are therefore widely used as core materials for electrical equipment such as transformers, rotating machines, and generators. Such silicon steel plates are produced by hot rolling steel ingots or continuous casting slabs into hot coils, which are then cold rolled and annealed to produce finished products with a predetermined thickness (0.28 to 0.50 mm). . In general, as the Si content increases in a silicon steel sheet, the saturation magnetic flux density decreases, but the magnetostriction decreases, resulting in a decrease in hysteresis loss.Also, since the electrical resistance increases, the eddy current loss decreases, which is desirable from an application standpoint. Characteristics arise. In particular, when the Si content is about 6.5%, magnetostriction virtually disappears and the best soft magnetic properties are exhibited. For this reason 1950
Attempts have been made since the 1990s to produce high-silicon steel sheets containing about 6% Si, but no results have been achieved to date because industrial rolling is virtually impossible. By the way, recently one of the inventors of the present application, for example,
No. 53-114847, No. 53-141290, etc., proposed a method for continuously manufacturing ribbons directly from molten steel, which is an extremely brittle material. According to this method, molten steel of a predetermined composition is immediately spouted from a nozzle onto a rotating body such as a roll rotating at high speed or a moving body such as a belt moving at high speed.
Thin strips with a thickness of 300 μm can be obtained continuously.
With this method, there is no rolling process, so 6.5%Si
Not only can even brittle materials such as silicon steel be easily made into thin strips, but also finished or semi-finished products can be manufactured in a single process, so manufacturing costs are much lower than in conventional processes. The economic and industrial benefits are significant. Now, in order to use such a thin ribbon as an iron core material for power transformers or rotating equipment, it is necessary to have a so-called (100) in-plane nondirectional structure in which the <100> axis, which is the direction of easy magnetization, is aligned parallel to the plate surface. This is desirable. Regarding this point, according to the invention described in the above-mentioned Japanese Patent Application No. 141290/1980, when a thin ribbon produced by rapid solidification is annealed at 1000 to 1300°C, a sharp (100)
A high-silicon steel ribbon having an in-plane oriented structure and excellent magnetic properties can be obtained. However, it is technically difficult to industrially anneal the ribbon at such a high temperature in a conventional box furnace or continuous furnace, and the drawback remains that it increases manufacturing costs. An object of the present invention is to provide a method for manufacturing a (100) in-plane non-oriented silicon steel ribbon, which eliminates and improves the drawbacks of the method for manufacturing a high-silicon iron ribbon, and the present invention is directed to the following: The above object can be achieved by the method described in the following. Next, the present invention will be explained in detail. As a result of various manufacturing experiments of silicon steel ribbon, the present inventors found that when molten silicon steel is rapidly solidified using twin rolls, under certain manufacturing conditions, the solidification structure itself becomes non-uniform in the (100) plane. The present invention was completed based on the knowledge that a directional tissue is formed. That is, the present invention continuously supplies molten steel containing 2.0 to 8.0% Si from a pouring nozzle between a pair of cooling rolls rotating at high speed, and the flux of molten steel supplied between the pair of cooling rolls is In producing a silicon steel ribbon by rapidly cooling and solidifying while forming a pool without expanding, the cross section of the spout tip of the nozzle is either circular or slit-shaped; When the cross section is circular, the hole diameter is D
(mm), when the cross section is slit-shaped, the length in the narrow direction is D (mm), and the diameter of the cooling roll is R (mm), then the D/R ratio is
This is a method for manufacturing a (100) in-plane non-oriented silicon steel ribbon made of silicon steel having a diameter of less than 0.006. Next, the present invention will be explained using experimental data. Molten steel containing 3.5% Si and the remainder substantially Fe is passed through a circular nozzle 3 between two stainless steel rolls 1 and 2 with the same diameter rotating at a circumferential speed of 10 m/sec as shown in Figure 1. More squirts and ribbons 4
was manufactured. In the above device, when twin rolls with a diameter R of 50 mm and a nozzle with a hole diameter D of 1.0 mm are used,
and twin rolls with diameter R of 400mm, hole diameter D of 0.5mm
The cross-sectional structure of the ribbon obtained when using the nozzle is shown in Fig. 2 A, B, and the (200) pole figure is shown in Fig. 2 C, D.
are shown respectively. Under the conditions of a roll diameter R = 50 mm and a nozzle hole diameter D = 1.0 mm having a circular cross section, columnar crystals grow at an angle of approximately 20° from the plate normal, resulting in a crystal grain size of <100 mm.
>The axes are also accumulated in a direction tilted in the longitudinal direction of the ribbon at an angle of about 20° from the plate normal. On the other hand, under the conditions of roll diameter R = 400 mm and nozzle hole diameter D = 0.5 mm, columnar crystals grow almost perpendicular to the plate surface, and as a result, the solidified structure has already become a (100) in-plane non-directional structure. There is. When used as a laminated core material, the structure shown in FIG. 2B is preferable for use compared to that of A, since magnetization may occur in different directions within the plane of the plate. Next, it contains 6.5% Si and the rest is impurities (O55ppm,
C50ppm, N60ppm, P0.01%, Mn0.01%,
Molten steel consisting of (Al0.006%, S0.005%) and Fe is
Thin strips were produced by ejecting the mixture onto twin rolls of various sizes from a nozzle having a slit-shaped cross section with a gap length of 20 mm and a gap length of 0.5 to 4 mm. The inclination angle θ of the <100> axis from the plate normal as seen from the (200) pole figures of these thin strips (more precisely, the angle between the direction that gives the highest value of [200] intensity and the plate normal), The relationship between the roll diameter and the gap length in the narrow direction of a nozzle having a slit shape is shown in FIG. As is clear from the figure, the larger the roll diameter and the smaller the gap length in the narrow direction of the nozzle, the smaller θ becomes, resulting in a better (100) in-plane non-directional structure.
In particular, in the condition range where θ is within 5 degrees, D/R<0.006 from FIG. 3, and within this range, a (100) in-plane non-directional structure is obtained. As will be seen from the Examples described below, such a relationship holds true regardless of the silicon content within the composition range where γ transformation does not occur. Therefore, in the present invention, the ratio D/ For R,
It was limited to a range smaller than 0.006. The reason why a good (100) in-plane non-directional structure can be obtained by setting D/R to less than 0.006 according to the present invention is considered to be as follows. In other words, in the twin-roll method, the solidified shell grows in the radial direction of the rolls, and this direction
100>, but if we consider the position where solidification starts (θ position in Figure 4), the <100> axis will be aligned in the normal direction of the plate if θ is as small as possible. Considering cos θ here, cos θ is expressed by the following formula cos θ=R−D/R=1−D/R. Therefore, the smaller D/R is, the smaller θ is. That is, the smaller D/R is, the more the <100> axis becomes parallel to the normal direction of the plate, in other words, the (100) plane becomes parallel to the plate surface. Therefore, in the present invention, the lower limit of D/R is not particularly defined. In addition, when using rolls with different diameters as the twin rolls, the diameter R of the rolls is the diameter of the smaller one of the twin rolls. This is because the inclination of the columnar solidified structure with respect to the plate normal direction is substantially determined by the smaller roll diameter. Furthermore, since it is necessary to prevent γ transformation from occurring after solidification, the Si content must be 2.0% or more. On the other hand, if the Si content exceeds 8.0%, the magnetostriction will increase and the magnetic properties will also change. The Si content must be within the range of 2.0 to 8.0%, since it is practically meaningless and disadvantageous because it deteriorates when exposed to heat. The silicon steel ribbon having a (100) in-plane non-directional structure produced in this way can be used as is or by cutting it and incorporating it into a laminated core.
In order to exhibit higher performance, this ribbon must be further annealed at a temperature below 1000°C, preferably within the range of 700 to 900°C, to remove the strain introduced during rapid cooling and increase the crystal grain size. is desirable. Although the crystal grains grow due to the annealing, the (100) in-plane non-oriented structure is maintained almost as it is. Also, when incorporating it as an iron core, a high space factor may be required depending on the application, and in such cases, the rapidly cooled ribbon is cold or warm rolled to give a smooth surface. , 1000°C, preferably 700-950°C. The silicon steel ribbon thus obtained can be subjected to a coating treatment for insulation, if necessary, to produce a finished product. Next, the present invention will be explained with reference to examples. Example 1 Molten steel containing 6.3% Si, 0.8% Al, 0.1% Mn and the remainder substantially Fe is passed through a slit-shaped nozzle with a width of 25 mm and a gap length of 1.5 mm through a slit-shaped nozzle with a diameter of 400 rpm rotating at 600 rpm.
The mixture was ejected between twin rolls of mm diameter, rapidly cooled, solidified, and rolled to obtain a ribbon with a thickness of 150 μm. This ribbon exhibited a good (100) non-oriented texture. This ribbon is annealed at 900℃ for 5 minutes.
(a), or by cold rolling the rapidly solidified ribbon.
The magnetic properties of the ribbon (b), which was made to a thickness of 100 μm and annealed at 900° C. for 5 minutes, were as shown in Table 1 below.

[Table] Example 2 Molten steel having the same composition as Example 1 was jetted from a slit-shaped nozzle with a width of 25 mm and a gap length of 2.0 mm between twin rolls with a diameter of 200 mm rotating at 1200 rpm.
A ribbon with a thickness of 130 μm was obtained by rapid cooling, solidification, and rolling. The peak position of the (100) direction seen in the (200) pole figure of this thin strip was tilted approximately 14 degrees from the plate normal. The magnetic properties of the ribbons (c) and (d) obtained by subjecting this ribbon to the same treatment as in Example 1 were as shown in Table 2.

[Table] Example 3 Contains Si2.3%, Mn0.5%, balance O2.5ppm,
Molten steel consisting of impurities of 50ppm C, 50ppm N, 80ppm Al and Fe is ejected from a multi-hole nozzle with a hole diameter of 0.5mm and a hole spacing of 3mm between twin rolls with a diameter of 100mm rotating at 2000rpm, rapidly cooled and solidified to obtain a ribbon with a thickness of 70μm. Ta. This ribbon (E) had a good (100) in-plane non-directional structure. This thin strip (E) and this thin strip are heated at 920℃, 3
The magnetic properties of the ribbon (f) annealed for 1 minute were as shown in Table 3.

[Table] Example 4 Molten steel having the same chemical composition as Example 2 was jetted between twin rolls of 800 mm in diameter rotating at 300 rpm from a multi-hole nozzle with a hole diameter of 2 mm and a hole spacing of 8 mm, and was rapidly cooled and solidified to form a ribbon with a thickness of 90 μm. I got it. This ribbon (g) had a good (100) in-plane non-directional structure. This thin strip (g)
This ribbon is annealed at 920℃ for 3 minutes.
The magnetic properties of (H) were as shown in Table 4.

[Table] According to the present invention, a silicon steel ribbon having a (100) in-plane non-oriented structure and excellent magnetic properties can be economically produced.

[Brief explanation of the drawing]

Fig. 1 is an explanatory longitudinal cross-sectional view of the twin rolls and nozzle used to carry out the method of the present invention, Fig. 2 A and B are views showing the longitudinal cross-sectional structures of two types of ribbons, Fig. 2 C , D are pole figures of a ribbon having structures corresponding to A and B, respectively, and Figure 3 shows the relationship between the gap length (mm) D of the slit-shaped nozzle and the diameter (mm) R of the twin rolls. FIG. 4 is an explanatory diagram of the solidification form of molten metal in the twin roll method.

Claims (1)

[Claims] 1. Molten steel containing 2.0 to 8.0% Si is continuously supplied from a pouring nozzle between a pair of cooling rolls rotating at high speed, and the molten steel flow is supplied between the pair of cooling rolls. In manufacturing a silicon steel ribbon by rapidly cooling and solidifying the molten metal while forming a pool without expanding the bundle, the cross section of the spout tip of the nozzle is either circular or slit-shaped. , when the cross section is circular, the hole diameter is D (mm), when the cross section is slit shape, the length in the narrow direction is D (mm), and the diameter of the cooling roll is R ( 1. A method for producing a (100) in-plane non-oriented silicon steel ribbon, characterized in that the D/R ratio is smaller than 0.006 (mm).