SU1180393A1 - Method of producing cold-rolled isotropic electrical steel - Google Patents

Abstract

1. A method for producing cold rolled isotropic electrotechnical steel, including a head of steel containing 0.02-1.5% silicon, 0.001-0.4% aluminum, hot rolling with a rolling end temperature depending on the chemical composition, winding at 680 720 0 cold rolling, intermediate and final annealing, characterized in that; In order to increase the magnetic properties of the cold-rolled metal by increasing the uniformity of the structure, the temperature of the rolling end is set in the single-phase austenitic or ferritic region and, depending on this temperature and silicon and aluminum content, rolling in the last pass is carried out with a degree of deformation in the range of 4-40% , 2. The method according to claim 1, that is, with the fact that at a rolling end temperature of 750-850С, corresponding to the ferritic region, and a silicon content of 1.0-1.5% and aluminum. Nor 0.20-0.40% rolling in the last S pass is carried out with a degree of deformation of 4-14%. CO 3. The method according to claim 1, characterized in that, at a rolling end temperature of 851-920 ° C, corresponding to the austenitic region, and a silicon content of 0.02-0.99% and aluminum 0.001-0.19% rolling the last pass is carried out with a degree of deformation of 21-40%, 00. 4. The method according to claim 1, characterized in that at a temperature of 300 the end of rolling 750-800 ° C, corresponding to the ferritic region, and holding silicon 0, 02-0.99% and aluminum 0.001-0.19%. Rolling in the last pass is carried out with a degree of deformation of 4-14%.

Description

one

The invention relates to ferrous metallurgy, in particular, to electrical steel obtained, and can be used in the manufacture of isotropic cold-rolled sheets of nimble and alloyed steels used for the manufacture of cores of electric motors.

The aim of the invention is to increase the magnetic properties of cold rolled electrical steel by increasing the homogeneity of the structure.

To ensure a high level of the magnetic characteristics of cold rolled isotropic electrical steel, it is necessary to obtain a homogeneous grain structure in hot rolled steel (Dmax less than 3)

A ferrite grain size of 40– 60 µm. In this case, during the final annealing of the cold rolled metal, the grains grow, leading to the development of a cubic component in the texture of the finished metal and to a high level of magnetic characteristics.

Obtaining a homogeneous structure of hot rolled strips is associated with the hot rolling mode.

Upon completion of the hot rolling of steel in the austenitic region, obtaining a homogeneous structure is achieved when the strain value exceeds 21% - the lower limit of the strain value. The upper limit of the degree of deformation in the last pass, equal to 40%, is due to technical difficulties (the impossibility of ensuring the required profile of the strip, an increase in the maximum allowable limits of the power rolling parameters).

Upon completion of metal rolling in a single-phase ferritic state, the formation of a homogeneous coarse-grained structure occurs after degrees of deformation in the range of 4-14%, which is likely due to the development of recrystallization after critical degrees of deformation. In this case, the orientation of the hot rolled strip {100 Ok, {110 {001, beneficial from the point of view of obtaining high magnetic properties in cold-rolled metal. Reducing the degree of deformation by less than 4%

803932

to obtain a different-grained structure, characterized by a surface area with large grains D 80 200 microns and a fine-grained matrix of 5 central metal layers. In addition, when deformed below 4%, the hot rolling process becomes unstable. An increase in the degree of deformation in the last pass of more than 14% results in a fine-grained structure of hot rolled steel. In this case, in the texture of the central layers, there is an increase in the octahedral components characteristic of the deformation texture and unfavorable in terms of obtaining the high magnetic properties of the finished metal, the temperature range of hot rolling in the region corresponding to

- single-phase ferritic state, on the one hand, is determined by the completeness of the recrystallization processes, on the other - by the position of critical points corresponding to

. the beginning of phase recrystallization,

In alloyed electrical steels x containing 1.0-1.5% silicon and 0.2-0.4% aluminum, the critical points lie above 850 ° C,

For this group of steels, the end of the hot rolling occurs in the ferritic or in the mixed ferritic austenitic state. The temperature limit of the end of the hot rolling is 850-750 ° C,

5 in steel with a silicon content of 0.02-0.99% and aluminum 0.001-0.19%, the critical point Ar lies at a temperature less than, which is the upper limit of the end of rolling,

 The lower temperature limit corresponds to 750 ° C. At lower temperatures at the end of rolling, recrystallization processes are difficult, and, in addition, they deteriorate

 plastic characteristics of the metal, it is difficult to winding into rolls.

For the same group of steels, high magnetic properties are achieved at the end of hot rolling in the austenitic region at 850–920 ° C. The lower temperature limit is 850 ° C due to the position of the upper critical point Apj for this group of steels.

5 hot rolling in the temperature range corresponding to the austenitic state, more leads to an intensive growth of the layer thickness of the LINES311, worsening the etching of the strip, as well as to the coarsening of the grain structure of the hot rolled strip, reducing its plastic properties. The method was tested in the manufacture of cold-rolled isotropic electrical steel. The melting of isotropic electrical steel was carried out in a 300-ton converter. The chemical composition of the bottoms, as well as the corresponding critical points of Ar and Ar, are given in Table. 1. Hot rolling of slabs into a 2.2-2.5 mm thick strip is carried out on a 1700 continuous broadband mill with degrees of reduction in the last pass in the range of 2-40%. The temperature of the end of rolling with this vari93. 4 ruyut in the range of 750-920s. Next, pickling is carried out, first cold rolling with a reduction of 77-79%, intermediate annealing in cap furnaces in a protective gas atmosphere at a temperature of 600 ° C, second cold rolling at a training mill 1700 for a final thickness of 0.50+ O 03 mm with a degree of deformation 4 10%, final certification annealing at 830 C. Modes of implementation of the method and properties of steel are given in Table. 2. As can be seen from the table. 2, the application of the proposed method for producing cold-rolled isotropic electrical steel makes it possible to increase the uniformity of the structure of the hot-rolled strip and the level of the magnetic properties of the finished metal. Table 1

2. 3 0.03 0.99 0.40 4 0.03 0.02 0.040 50.03 0.02 0.040

745

The geometry of the strip is unsatisfactory, the cold limit was not made

2

four

45 58 53 1.2

eight

14

sixteen

35

1.64 6.2

Ferrite

1.2 1.61 8.0 0,0120,030,001792 892 882 0,014 0,030,19803 903 853 0,013 0,030,001730 830 780 1Table2

59 1.4 1.66 6.2

850 8

(by well-known

Continuation of table 2

ti

Claims (4)

1. METHOD FOR PRODUCING COLD-ISOTROPIC ELECTROTECHNICAL STEEL, including the smelting of steel containing 0.02-1.5% silicon, 0.001-0.4% aluminum, hot rolling with a temperature of the end of rolling, depending on the chemical composition, winding at 680-720 C , cold rolling, intermediate and final annealing, characterized in that; In order to increase the magnetic properties of the cold-rolled metal by increasing the uniformity of the structure, the temperature of the end of rolling is set in a single-phase austenitic or ferritic region and, depending on this temperature and the content of silicon and aluminum, rolling in the last pass is carried out with a degree of deformation in the range of 4-40%. 2. The method according to p. ^ Characterized in that at a temperature of rolling end of 750-850 ° C, 'corresponding to the ferritic region, and a silicon content of 1.0-1.5% and aluminum 0.20-0.40% rolling in the latter the passage is carried out with a degree of deformation of 4-14%. . 3. The method of pop. 1, characterized in that at a temperature of rolling end of 851-920 ° C, corresponding to the austenitic region, and a silicon content of 0.02-0.99% and aluminum 0.001-0.19%, rolling in the last pass is carried out with a degree of deformation of 21-40 % 4. The method according to π. 1, characterized in that at a temperature of the end of rolling 750-800 ° C, corresponding to the ferritic region, and a silicon content of 0.02-0.99% and aluminum 0.001-0.19%, rolling in the last pass is carried out with a degree of deformation 4-14%. SU „„ 1180393