JPS59104482A - Manufacture of rapidly-cooled thin strip of silicon steel excellent in iron loss property - Google Patents

Abstract

PURPOSE:To obtain the titled rapidly-cooled thin strip of silicon steel improved in an iron loss property, by applying the aqueous slurry of an annealing parting agent prepd. by compounding hydrous siliceous mineral powder in Al2O3 powder to the surface of a rapidly-cooled thin strip of silicon steel, coiling the coated strip, and then coil annealing it. CONSTITUTION:Molten steel containing 4.0-8.0wt% Si is rapidly solidified by continuously supplying it onto a cooling body. The aqueous slurry of a mixture prepd. by compounding 5-50% hydrous silicate mineral powder such as serpentine in Al2O3 powder is applied as an annealing parting agent onto the surface of said rapidly-cooled thin strip. Thereafter, the coated strip is dried with heat, coiled and finally finish annealed at 1,100-1,300 deg.C. By this method, the burning of Al2O3 particles is practically eliminated, so that the exfoliation of the annealing parting agent after annealing is facilitated. Consequently, the rapidly-cooled thin strip of silicon steel improved in an iron loss property is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a silicon steel quenched ribbon having excellent iron loss characteristics.

Traditionally, so-called silicon steel sheets have been used as iron core materials for power transformers, power distribution pole transformers, rotating machines, lamp ballasts, etc. for more than three-quarters of a century because they have excellent soft magnetic properties and are easy to use. It has been widely used for a long time.

However, the manufacturing process for such silicon steel sheets is extremely complicated, so even with modern technology, it is quite difficult to manufacture, requiring sophisticated technology, and in addition, the manufacturing cost is higher than that of other steel types. There was a disadvantage in comparison.

By the way, recently, molten metal is continuously supplied from a circular hole-shaped or slit-shaped nozzle to the surface of a cooling body, such as a roller, whose cooling surface is updated at high speed, and the molten metal is rapidly solidified. A method for manufacturing ribbons has been developed.

By using such a quenched ribbon manufacturing method, 4% by weight of Sl (hereinafter simply referred to as % High-silicon steel containing more than a certain degree (shown by ) can now be easily made into ribbon, and currently
High-silicon steel electromagnetic ribbons with a content of 6.5% are actually manufactured. Moreover, this manufacturing method has the great advantage of being able to significantly reduce the energy required for manufacturing and the manufacturing cost, since all complicated rolling steps can be omitted.

Although the silicon steel ribbon thus obtained can be used in the quenched state, the magnetic properties may not be sufficient depending on the application, and in such cases it is usually heated at 1100 to 1350°C. Magnetic properties can be improved by performing annealing treatment in a temperature range of about 100%.

Specifically, this annealing treatment is performed on the surface of the ribbon after rapid solidification.
After applying an annealing separator and winding it into a coil, it is finished annealed at a high temperature in a batch furnace or the like.

Finish annealing at such high temperatures causes tertiary recrystallization using surface energy as the main grain boundary driving force, and after the completion of tertiary recrystallization annealing, it is immediately cooled, the separating agent is removed, and the product sheet is processed. However, depending on the application, an insulating film may be further formed.

By the way, aluminum oxide powder has conventionally been mainly used as the annealing separator as described above.

This aluminum oxide powder is excellent as a separating agent when annealing is performed at a temperature of about 1000°C, but
During annealing at temperatures as high as 1850°C, which is the subject of this invention, aluminum oxide particles are baked onto the surface of the steel sheet and cannot be removed to a satisfactory extent in the subsequent separation agent removal process. There were many. When we investigated this seizure phenomenon in detail, we often found that aluminum oxide particles were embedded in the surface of the steel sheet. The reason why such seizure occurs has not yet been clearly elucidated, but as will be explained in detail later, aluminum oxide is inert and has poor thermal conductivity, so it does not expand or contract. This is thought to be because the atmosphere cannot be sufficiently circulated between the coil layers.

The residual fine particles on the surface of the steel sheet due to such seizure not only significantly deteriorate the magnetic properties of the steel sheet.
This was a major impediment to the subsequent formation of an insulating film.

The present invention advantageously solves the above problems by using silicate ore powder containing water of crystallization in aluminum oxide powder as an annealing separator during final annealing of silicon steel quenched ribbon at high temperatures. By adding and blending the appropriate amount, it is possible to effectively prevent seizure of aluminum oxide particles during annealing, and at the same time, it is extremely easy to peel off and remove the separating agent, which in turn helps improve magnetic properties. Based on new knowledge.

That is, this invention continuously supplies molten steel containing 4.0 to 8.0% Si onto a cooling body whose cooling surface is updated and moves at high speed, rapidly solidifies it into a thin ribbon, and then A water slurry of a mixture of aluminum oxide powder and hydrated silicate mineral powder added in a range of 5 to 50% as an annealing separator is applied to the surface of the quenched ribbon, and then heated and dried. After winding it into a coil,
This is a patented method for producing rapidly solidified silicon steel ribbon, which is characterized by final annealing in a temperature range of 350°C.

In this invention, serpentinite, talc, bentonite, kaolin, acid clay, activated clay, and the like are advantageously suitable as the hydrous silicate minerals that are the constituent components of the annealing separator, and their particle sizes include aluminum oxide powder. Approximately 1 to 10 μm is suitable.

This invention will be specifically explained below.

First, in this invention, Sl is contained in a range of 4.0 to 8.0%, but if the Si content is less than 4.0%, the desired magnetic properties cannot be obtained; %, the magnetic flux density decreases significantly.

Further, in this invention, in addition to the above-mentioned Sl, Mn, Co, and N1 are added to improve magnetic properties, and S, SerTe, and Sb are added as grain growth suppressing components.
.

Sn, As, Mo, TarTi,
Zr, V, Nb and AI? etc. can be contained in small amounts.

Now, the molten steel adjusted to a predetermined composition is rapidly solidified to form a thin ribbon.
Any conventionally known method such as the twin roll method or the rotating drum method can be used, and thickness -ll. It is made into a quenched ribbon at a temperature of 50 to 500 μ-rnm.

Next, high-temperature finishing annealing is performed to improve the magnetic properties, and as an annealing separation agent at this time, a water slurry of a mixture of 5 to 50% of the above-mentioned hydrated silicate mineral powder added to aluminum oxide powder is used. That's why.

By using an annealing separator with such a mixing ratio,
Even if finish annealing is then performed at a high temperature of 1,100 to 1,350°C, there will be almost no burn-through of the aluminum oxide particles, and it is also extremely easy to remove flakes after annealing.The reason for this is that can be considered as follows.

That is, during the temperature rise during annealing, the water in the hydrated silicate mineral powder begins to evaporate at around 400°C, and completely disappears when the temperature rises further. Therefore, gaps are created between the coil layers, which improves the circulation of atmosphere between the coil layers. As a result, the surface of the steel plate is activated, and the aluminum oxide powder no longer seizes.

However, if the proportion of hydrated silicate mineral powder in the annealing separator is less than 5%, the formation of gaps between the coil layers during final annealing is small and sufficient atmosphere circulation cannot be achieved; However, the circulation of the atmosphere will not be so good, and it will be rather uneconomical. Therefore, the blending amount of the water-containing silicate mineral powder was set in the range of 5 to 507°.

Furthermore, if the final annealing temperature is less than 1100°C, there is a disadvantage that it takes a long time to complete the tertiary recrystallization;
If the temperature exceeds .degree. C., there is a risk that the surface layer will melt if the surface softening of the steel sheet is severe, and it will also put stress on the equipment, so the final annealing temperature was set in the range of 1100 to 1 to 850.degree.

Examples of the present invention will be described below.

Examples 1 to 2 Molten steel containing 6.5% Si and the remainder substantially Fe was formed into a thin strip by a twin roll method, and a strip having a width of 4
A silicon steel ribbon having a thickness of 50 mm and a thickness of 110 μm was prepared. The surface of this ribbon was smooth and had a metallic luster.

Next, on the surface of this ribbon, aluminum oxide powder (Ag2O3) only, aluminum oxide powder + 20% serpentine powder (Ae2o8 + 20% 3Mg0-
28iO□-2H20) and aluminum oxide powder +
30% activated clay powder (Ae208+80%Ag2s1.
A water slurry of each of the three types o□o(oH')2-llH2O) was applied, then heated and dried, wound into a coil, and then placed in a box-type annealing furnace at 1150
A final annealing was performed at ℃ for 3 hours.

Thereafter, the separating agent was peeled off and removed, but this separating agent removal could be easily carried out and almost no burning of Ag2O3 occurred.

Table 1 summarizes the results of investigating the number of seizing Ae203 per 1 mm2 and iron loss characteristic W1%0 of each silicon steel ribbon obtained in Table 1.

Table 1 As is clear from Table 1, the silicon steel ribbon obtained according to the present invention can reduce the number of seizing Ae208 particles, which was 22 per 1 mm2, to 1 or less, and moreover, Loss characteristics are significantly improved.

Examples 3 to 4 Molten steel containing Si: 6.7%, Mn: 0.5% and the remainder substantially having a composition of Fe was formed into a thin strip by a twin roll method, and the plate width was soOmm and the plate thickness was 180μ77L
A quenched ribbon of high-yield steel of I was prepared. Next, on the surface of this ribbon, talc (Mga
S 140'. A water slurry made by adding (OH)2) and bentonite powder at 30% each was applied at a rate of 15p per unit area of 1 m2, then heated and dried, wound into a coil, and then placed in a box annealing furnace. Final annealing was performed at 1150°C for 3 hours.

The subsequent peeling and removal of the separating agent can be easily carried out.
The number of Ae203 particles seized per -1mlrL'' and the iron loss characteristic W1815o of each of the obtained ribbons were as shown in Table 2.

Table 2 The silicon steel ribbons obtained using the annealing separator according to the present invention, especially in Example 8, are shown in All! There was no seizure of the 208 particles, and the iron loss value was clearly reduced to approximately that of a wing compared to the conventional example of Clothe 1 mentioned above.

As described above, according to the present invention, it is possible to almost completely prevent the annealing separation and simultaneous seizure, which was considered unavoidable in the past, during finish annealing of rapidly solidified silicon steel ribbon at high temperatures, and it is also possible to improve iron loss characteristics. Helpful.

Claims (1)

[Claims] Molten steel containing LSi: 4.0 to 8.0% by weight is continuously supplied onto a cooling body whose cooling surface is updated and moved at high speed,
A mixture of aluminum oxide powder and hydrated silicate mineral powder added in an amount of 5 to 50% by weight as an annealing separator is added to the surface of the obtained quenched dynamic zone after quenching and solidifying it into a thin ribbon. A method for manufacturing a patented silicon steel quenched ribbon, characterized by applying a water slurry of 1,000 to 1,000 ℃, followed by heating and drying, winding into a coil, and final annealing in a temperature range of 1,100 to 1,350°C.