JPS6044395B2 - Annealing separator for grain-oriented silicon steel sheets - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an annealing separator for improving the magnetic properties of grain-oriented silicon steel sheets.

A grain-oriented silicon steel sheet is a silicon steel sheet whose <001> axes, which are easily magnetized, are aligned at high density in the rolling direction by secondary recrystallization through high-temperature annealing at 1200°C.

The annealing separator is used to prevent the steel sheets from seizing together during this high-temperature annealing, but the annealing separator also plays an important role in improving the magnetism of grain-oriented silicon steel. the current,
The unidirectional silicon steel sheet manufactured as a grain-oriented silicon steel sheet utilizes a phenomenon in which (110) <001> crystals with a <001> axis grow preferentially during high-temperature secondary recrystallization.

This secondary recrystallization process has a low surface energy (110
) plane grows preferentially and AIN, MnS are dispersed in the steel.
It is believed that (110)<001> crystals grow preferentially because they erode other crystals whose growth is suppressed by nonmetallic inclusions such as. Therefore, in order to produce grain-oriented silicon steel sheets with excellent magnetic properties, the state of dispersion of non-metallic inclusions such as AIN and MnS in the steel and the speed of decomposition of these non-metallic inclusions are important. The decomposition of nonmetallic inclusions during high-temperature annealing is influenced by the oxide film on the surface of the steel sheet, impurities in the annealing separator, and the annealing atmosphere. The present invention aims to improve the magnetism by controlling the oxide film on the surface of the steel sheet. In particular, it attempts to maintain a uniform oxide film on the surface of the steel sheet by controlling the oxidizing properties of the high-temperature annealing atmosphere. During high-temperature annealing, the decomposition of magnesia (water-containing) used as an annealing separation agent creates an oxidizing atmosphere containing water, and Fayalite (Fe
2Si00), Sillca (SiO2), Aluminum
Oxides such as rkl (Al2O3) and manganese oxide (Mn00) are formed on the surface of the steel sheet.

These oxide films contain nonmetallic inclusions (A
]N, MnS, etc.) and change the growth behavior of secondary recrystallization. Particularly in the case of grain-oriented silicon steel sheets that can obtain high magnetic flux density, the density of the oxide film on the surface of the steel sheet is important because AIN is affected by the N2 partial pressure in the annealing atmosphere. The oxide film on the surface of the steel sheet is formed by decarburization annealing, but the oxide film formed by decarburization annealing is easy to manage, but the oxide film formed by high temperature annealing is due to the hydration of magnesia, an annealing separator. Because of this instability, the oxidizing properties of the high-temperature annealing atmosphere fluctuate, leading to deterioration of magnetism.

Therefore, in the present invention, we investigated measures to reduce the influence of the oxide film formed during high-temperature annealing as much as possible, and found that if a metal powder that is poorly soluble in water and has strong oxidation is added to the annealing separator magnesia, the decomposition of hydrated magnesia can be prevented. It has been found that oxidation of the steel sheet during high-temperature annealing can be suppressed because the H2O thus generated can be removed by reaction with the metal powder.

According to this method, it is only necessary to control the oxide film during decarburization annealing, and grain-oriented silicon steel with stable magnetism can be manufactured.
The metal powder used in the present invention is Al, which has a higher oxidizing power than Fe, has a stronger oxidizing power than Fe, is sparingly soluble in water, and can improve the properties of electrical steel sheets. Si, Ti, Cr, Zr, Nb
, Sn, W, MO, and other metal powders are suitable.

A metal that oxidizes weaker than Fe, which accounts for about 97% of grain-oriented silicon steel sheets, is not suitable because the steel sheet oxidizes earlier. Furthermore, metals that are easily soluble in water become hydroxides and release water during high-temperature annealing, which is not preferable. The amount of these metal powders added is 0.1 to 10% of the magnesia used as the annealing separator.
Add % by weight.

If the amount added is less than 0.1%, there is no effect of suppressing oxidation of the steel plate annealed at high temperature, and if it is added more than 10%, Fayalite (Fe2SiO4) formed by decarburization annealing is reduced too much, which is not preferable. Next, the present invention will be specifically explained.

The material of the present invention contains 2-4% Sl, AlO. Ol~0.0
5%, MnO. O2~0.20%, NO. OO3~0.
010%, CO. Ol~0.1%, SO. Ol~0.0
3% and other unavoidable components is used.

This steel ingot is produced by hot rolling, hot rolling plate annealing, pickling, and cold rolling according to the general manufacturing method! The plate is rolled to a thickness of 0.2 to 0.35 T$. Then, this silicon steel plate is decarburized and annealed using a mixed gas of H2 and N2 containing water vapor. After decarburization annealing, the magnesia slurry of the present invention is applied to the steel plate. This magnesia slurry liquid contains AI, Si, Ti, Cr, Zr.
, Nb, Sn, 5W, and MO. The magnesia that is the main component of the annealing separator in the present invention may be light magnesia that is easily soluble in water, or magnesia clinker that is insoluble in water.

Additionally, a TiO2,B compound may be added as necessary. Silicon steel plate coated with magnesia slurry is 200
Dry at ~300°C to remove water and wind into coils. Next, the silicon steel sheet is annealed at a high temperature of 1200° C. in a mixed gas of H2 and N2 to undergo secondary recrystallization, and the atmosphere is changed to an H2lOO% atmosphere to remove impurities in the steel to obtain a grain-oriented silicon steel sheet. Next, examples will be shown.

Example 1 S13.0%, AlO. O28%, MnO. O8O%,
NO. OO8%, SO. O24%, CO. A silicon steel ingot with a composition of O6O% was cold-rolled for 0.2h by hot rolling, hot-rolled plate annealing, pickling, and cold rolling, and then H2O/H2 = 0.46, H2
/N2=3 decarburizing atmosphere 8500Cx150sec
Decarburization annealing was performed.

15f of slurry of the following composition was applied to the surface of this decarburized annealed plate.
1 d was applied. magnesia 1
00fr Titanium oxide 5 Metallic titanium 5 The silicon steel plate coated with this annealing separator was high-temperature annealed at 1200° C. for 2 hours.

Example 2 A decarburized annealed plate produced in the same manner as in Example 1 was coated with 15y1 of Slurly having the following composition, and annealed at a high temperature of 1200° C. for 2 hours.

Magnesia 100yr Titanium oxide 7 Metallic silicon
2 Metal tin
2 Comparative Example 1 A decarburized annealed plate produced in the same manner as in Example 1 was coated with 15 fI of a slurry having the composition below, and annealed at a high temperature of 1200° C. for two cycles.

Magnesia 100gr titanium oxide 5f1r Example 3 S13.3%, AlO. O27%, MnO. O7O%,
NO. OO8%, SO. O24%, CO. A silicon steel ingot with a steel composition of O7O% was cold rolled to 0.23T1rIf& by hot rolling, hot rolling sheet annealing, pickling, and cold rolling.
= 0.40, H2/N2 = 3 decarburizing atmosphere at 850°C
Decarburization annealing was performed for 150 seconds.

Then, a slurry of the following composition was applied to this decarburized annealed plate.
It was coated with Y1 and annealed at 1200°C for two cycles.
Magnesia 100f1r titanium oxide 5 metal zirconium
4 Example 4 A decarburized annealed plate produced in the same manner as in Example 3 was coated with a slurry having the following composition for 12yI, and annealed at a high temperature for a heating time of 120.

Magnesium clinker 100yr Magnesium hydroxide 5 Titanium oxide
5 Metallic aluminum 3 Metallic tungsten 3 Comparative example 2 A decarburized annealed plate produced in the same manner as in Example 3 was coated with 12y1rf1 slurry having the following composition, and annealed at 1200° C. for 2 hours at a high temperature.

Magnesia 100fr titanium oxide
5 Example 5 S13.3%, MnO. O8O%, SO. O25%, C
O. A silicon steel ingot with a composition of 5% O was heated to 0.23 mole by hot-rolling, pickling, cold-rolling, annealing, cold-rolling and charcoal annealing. A slurry having the following composition was coated at 12f1I on a silicon steel plate.

The silicon steel plate coated with this annealing separator was subjected to high-temperature annealing at 1200° C. for 2 hours. magnesia
100g titanium oxide 1 metal zirconium 3 Example 6 A decarburized annealed plate produced in the same manner as in Example 5 was coated with 10f1d of a slurry having the following composition, and high-temperature annealing was performed at 1200° C. for 20 hours.

Magnesia 100yr titanium oxide
1 Niobium metal
3 Metallic Chromium 3 Metallic Molybdenum 1 U Intersection 3 A decarburized annealed plate produced in the same manner as in Example 3 was coated with 12ml of slurry having the same composition, and was annealed at a high temperature of 1200°C.

Magnesia 100yr titanium oxide
The magnetism of grain-oriented silicon steel sheets made by one or more methods is shown in k1.

From the results in Table 1, Examples 1 and 2 were compared to Comparative Example 1 and Example 3.
-4 had better magnetism than Comparative Example 2, and Examples 5-6 had better magnetism than Comparative Example 3.

Claims (1)

[Claims] 1 Al, Si, Ti, Cr, Zr, Nb, Sn, W,
An annealing separator for grain-oriented silicon steel sheets, containing 0.1 to 10% by weight of one or more metal fine powders selected from Mo based on magnesium oxide.