JPS5956582A - Stick-off coating for annealing for grain oriented silicon steel sheet - Google Patents

Abstract

PURPOSE:To manufacture a grain oriented silicon steel sheet having superior magnetism and a superior glass film, by using a stick-off coating for annealing obtd. by adding a specified amount of Sb2(SO4)3 to MgO. CONSTITUTION:This stick-off coating for annealing for a grain oriented silicon steel sheet is obtd. by adding 0.1-2.0pts.wt. fine-grained Sb2(SO4)3 to 100pts.wt. MgO powder. Th grain oriented silicon steel sheet cold rolled to the desired thickness after steel making, hot rolling and annealing is subjected to decarburization annealing. It is coated with a slurry of the protective coating material and dried. The coated steel sheet is coiled and annealed at a high temp. The grain oriented silicon steel sheet having superior magnetism and a uniform superior glass film can be obtd. by using the protective coating material.

Description

DETAILED DESCRIPTION OF THE INVENTION This relates to a 1+t% blunt separating agent for a grain-oriented electrical steel sheet.

A oriented silicon copper plate is a silicon steel plate that is not easily magnetized and whose ooi> axes are aligned with high density in the rolling direction, and is produced by secondary recrystallization by high-temperature annealing at 1000° C. or higher. The annealing agent F41il is used to prevent the steel plate from burning during high-temperature annealing, and currently Magnesia is used. The reason for this is that Mn in the steel used as a growth promoter for secondary recrystallization of grain-oriented silicon steel sheets.
This is because Magnenya has the function of removing S and the function of forming an insulating film called a glass film.

Magnesia used as an annealing separator has a great influence on the magnetism and performance of glass coatings due to this secondary recrystallization, and therefore, many inventions have been disclosed regarding additives and impurities in magnesia.

The present invention is based on the knowledge that by adding antimony sulfate to magnesia, an annealing separator, grain-oriented electrical steel sheets with excellent magnetism and glass coating can be produced.

Magnesia, an annealing separator, contains a small amount of magnesium oxide as an impurity, and it was found that this amount of magnesium oxide affects the properties of grain-oriented silicon steel sheets. It is thought that the impurity magnesium sulfate is due to sulfuric acid in the seawater used as a raw material for Magnesia, and is converted to magnesium sulfate through calcination.

The present inventors investigated various sulfates for improving the magnetism and glass coating of grain-oriented silicon steel sheets, and found that antimony sulfate is even better than magnesium sulfate. The reason why antimony sulfate is excellent as an additive is that among sulfates, alkaline salts such as sodium sulfate cannot be used because they inhibit the formation of a glass film, and sulfates that are soluble in water are not suitable for addition. Whereas it becomes stable and undesirable,
This is because antimony acid does not inhibit the formation of a glass film and is insoluble in water, so the amount added can be controlled accurately.

According to the present invention, the amount of antimony sulfate to be added to Magnesia is 0.1 to 2 () parts by weight per 100 parts by weight of Magnesia. Addition exceeding the 2.0 type foil portion deteriorates both the magnetic properties and the properties of the glass film. Further, if it is less than 0.1 part by weight, no improvement in magnetism can be expected, so it is limited to this range. The particle size of the antimony sulfate to be added is preferably 100 μm or less.

(The magnesha used as the γ55 part release agent has the same effect whether it is a light magnesha made by firing at a low temperature or a magnesha clinker made by firing at a high temperature.
In particular, magnesia clinker fired at a high temperature has very little sulfate, so it has a remarkable effect.

The annealing separator of the present invention is effective even when contained in combination with titanium oxide or a zolon compound.

Next, an example of a method for producing a grain-oriented silicon steel sheet using the annealing separator of the present invention will be described.

Grain-oriented silicon steel plate is a hot topic in steel manufacturing! 1L plate-fired, cold-rolled, charcoal annealed, and Takagata annealed. The annealing separator of the present invention can be applied to the target plate J[? A grain-oriented silicon steel sheet that has been cold-rolled is coated with a slurry liquid on a decarburization annealing plate.

The coating weight of the annealing separator is 5 to 20 g/ln'', and the sheet is dried at 200 to 300° C. to remove moisture. The silicon steel plate coated with the annealing separator is wound into a coil and annealed at a high temperature.

The effects of the annealing separator of the present invention will be shown below using an example of M11.

Example I C: 0.049%, 81: 2.97%, acid soluble At: 0
．． A silicon steel ingot containing 0.028CH, S: 0.025% was hot-rolled to a thickness of 2.3, annealed at 1130° C. for 2 minutes, and then pickled. The steel sheet was then cold rolled to a thickness of 0.297 mm and then decarburized and annealed at 850°C for 150 minutes in a humid atmosphere.This steel plate was compounded with 25 parts of Tl0 to 100 parts of Mg0, and further antimony sulfate 5b2 (S04 )3
An annealing separator containing 0 to 3 parts of annealing agent was applied to a steel plate. The hydration water content of the annealing separator at this time was 2.7%. This steel plate was subjected to final finish annealing at 1200°C for 20'hr. The results are shown in Table 1.

Table 1 Example 2 C: 0.045%, st: 3. ts%, Mn: 0.06
A silicon steel ingot containing S: 8% and S: 0.023% was hot rolled to a thickness of 2.15'. This was pickled and transferred for 6s.
After cold rolling to % and annealing at 980°C, the final plate Jw,
It was cold rolled to 0.29-. Next, decarburization annealing was performed at 830° C. for 120 minutes in a humid atmosphere. After applying an annealing separator containing 20 to 3 parts of acid anhydride to 100 parts of Mg by electric resistance welding to this steel plate, final finish annealing was performed at 200° C. for 20 hours. Table 2 shows the glass film and magnetic properties of the samples after annealing.

Table 2 Example 3 C: 0.050%, Sl: 3.10%, A/! , :0.
028%, S: (1,025%) was hot-rolled to a thickness of 2.3, hot-rolled at 1130° C. for 2 minutes, and then pickled.

Next, it was cold rolled to a thickness of 0299, and then rolled to a thickness of 150°C at 850°C.
Second P1120/H2: Decarburization annealing in hydrogen gas of 0.46.

This steel plate was mixed with 100 parts by weight of Magnesia, 5 parts of magnesium hydroxide, 5 parts of titanium oxide, 0.4 g of borax, and further added with 0 to 3 parts of antimony sulfate and annealed. A separating agent was applied.

The coating mass is 15 g/m2. This steel plate is heated to 1200℃
20 hours of pot temperature annealing was performed. The results are shown in Table 3.

Table 3 Patent applicant: Nippon Steel Corporation

Claims (1)

[Claims] Antimony sulfate is 0.1 parts per 100 parts by weight of magnesha.
1-2. Annealing separator for grain-oriented silicon steel sheet characterized by containing an oil li part