RU2540243C2 - Production method of high-permeability electrical isotropic steel - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention relates to ferrous metallurgy, and namely to production of high-permeability electrical isotropic steel used for production of magnetic cores of electrical machines. In the production method of high-permeability electrical isotropic steel, which involves melting, steel pouring, hot rolling, heat treatment of a hot-rolled strip, etching, cold rolling and heat treatment of the cold-rolled strip, at steel melting there met is the ratio of 0.16%≤Al+P≤0.50% at the following content of components, wt %: carbon not more than 0.04, silicone 0.10-2.50, aluminium 0.10-0.23, phosphorus 0.06-0.27, manganese not more than 0.40, sulphur not more than 0.010, nitrogen not more than 0.008, iron and inevitable impurities are the rest. The strip obtained after etching is subject to cold rolling at deformation degree equal to 70-80%.

EFFECT: improvement of magnetic properties of high-permeability electrical isotropic steel.

1 ex, 1 tbl

Description

The invention relates to ferrous metallurgy, specifically to the production of cold-rolled electrical isotropic steel used for the manufacture of magnetic circuits of electrical machines (electric motors, generators, chokes, etc.).

A characteristic feature of the quality of such steel is a higher level of magnetic induction and relative peak magnetic permeability. In many respects, these characteristics are achieved by optimizing the structural and texture states of steel, which are largely determined by the chemical composition and technology of metal processing.

One way to increase the values of magnetic induction and relative peak magnetic permeability is to increase the fraction of cubic orientations of the steel texture (200), (310), which provide a significant improvement in the magnetic properties of the metal along and across the rolling direction.

In this case, the (111) texture, which worsens the magnetic properties and the rib texture (220), leading to anisotropy of the magnetic properties along and across the rolling direction, should be weakly developed or suppressed.

In order to reduce the development of textures (111) and (220), additives of special elements, such as phosphorus, are used, which allows you to control the texture.

Phosphorus, segregating along the grain boundaries, provides a smaller hardening of the grains of cubic orientations during cold rolling, which reduces their surface energy. In the process of heat treatment of cold rolled steel, grains of cubic orientations, possessing minimal energy, grow due to grains with orientations (111) and (220).

When phosphorus is introduced into steel, it is necessary to take into account the level of metal alloying with aluminum, since their ratio affects the texture formation of steel and the processability of rolling processing.

A known method of manufacturing an electrotechnical isotropic steel is given in the German patent, application No. 19918484, C21D 8/12 of 04/23/1999, in which aluminum and phosphorus are used to improve magnetic properties.

The method includes hot rolling a steel slab containing, wt.%: Carbon 0.06; silicon 0.02-2.5; aluminum no more than 0.40; manganese 0.05-1.0; phosphorus 0.08-0.25 to a thickness of not more than 3.5 mm, annealing of the hot-rolled strip at a temperature of 650-850 ° C, etching and cold rolling to a thickness of 0.2-1.0 mm with a total deformation of not more than 85%, recrystallization annealing of cold rolled steel at a temperature of 580-780 ° C and training with compression of 15%.

However, this method does not take into account the influence of the chemical composition, the ratio of aluminum and phosphorus in the metal is chosen arbitrarily, which affects the development of cubic components of the texture, an increase in the pole density of cubic orientations (200) and (310) is not achieved in the entire claimed range of the degree of deformation during cold rolling, and at the final stage of the technological process produce training. This reduces the level of magnetic induction and relative peak magnetic permeability.

The technical problem to which the invention is directed is to improve the magnetic properties of cold-rolled electrical isotropic steel, namely, increasing the degree of isotropy while reducing the anisotropy of specific magnetic losses, increasing the level of magnetic induction and relative peak magnetic permeability.

To solve the problem in the proposed method for the production of highly permeable electrical isotropic steel, including smelting, steel casting, hot rolling, heat treatment of a hot rolled strip, pickling, cold rolling and heat treatment of a cold rolled strip, the ratio of 0.16% ≤Al + P≤0 , 50%, with the following content of components, wt.%:

carbon no more than 0,04 silicon 0.10-2.50 aluminum 0.10-0.23 phosphorus 0.06-0.27 manganese no more than 0.40 sulfur no more than 0,010 nitrogen no more than 0,008 iron and inevitable impurities rest

where Al is the aluminum content in steel, wt.%; P is the phosphorus content in steel, wt.%. Obtained after etching, a strip of such steel is subjected to cold rolling at a degree of deformation equal to 70-80%.

To obtain a highly permeable electrotechnical isotropic steel with a high level of magnetic properties, it is necessary to form the optimal grain size in the metal and increase the pole density of the cubic texture orientations (200) and (310).

The results of our studies suggest that in order to obtain the optimal micrograin size and increase the pole density of the cubic orientations (200) and (310) in the texture of cold-rolled strips, it is necessary to use steel with a certain ratio of aluminum to phosphorus, and cold rolling of such steel must be carried out at a degree of deformation 70-80%.

Based on laboratory and industrial experiments, the boundary conditions for the content of the main elements in steel were established. The proposed method extends to electrical isotropic steels with a silicon content of Si = 0.10-2.50%. The lower limit is due to an increase in the specific magnetic losses of the finished steel due to a decrease in the electrical resistivity of the metal with a silicon content of less than 0.10%, and the upper limit is due to a decrease in the processability of rolled products due to an increase in the hardness of the metal with an increase in the ratio (Al + P) of more than 0, fifty%.

The range of alloying steel with aluminum is set equal to 0.10-0.23%. The lower limit is due to a decrease in the effect on the structural and texture state of finished steel with an aluminum content of less than 0.10%, and the upper limit is due to an increase in the number of non-metallic inclusions based on finely dispersed Al ₂ O ₃ oxide with an aluminum content of more than 0.23%, which leads to a decrease magnetic induction and relative peak magnetic permeability.

The range of phosphorus content in the metal, equal to 0.06-0.27%, is established based on the limits of the ratio of aluminum to phosphorus 0.16% ≤Al + P≤0.50%. The lower limit of phosphorus content is due to a decrease in the effect of suppressing textures (111) and (220) in the strip surface with a decrease in the ratio of aluminum to phosphorus (Al + P) of less than 0.16%, and the upper limit is due to a decrease in the ductility of metal during cold rolling of hot rolled products with a ratio aluminum and phosphorus (Al + P) more than 0.50%.

The range of the degree of deformation during cold rolling is set equal to 70-80%.

The lower limit is due to an increase in the anisotropy of the specific magnetic losses of the finished steel due to an increase in the fraction of rib texture (220) in the finished metal at a degree of deformation of less than 70%, and the upper limit is due to a decrease in the processability of rolled metal processing due to an increase in the rigidity of the metal at a degree of deformation of more than 80% .

Analysis of the patent literature shows the absence of distinctive features of the claimed method with the signs of known technical solutions. Based on this, it is concluded that the claimed technical solution meets the criterion of "inventive step".

The application of the invention improves the magnetic properties of cold-rolled highly permeable electrical isotropic steel, including reducing the anisotropy of specific magnetic losses ΔP _{1.5 / 50} by 5-8%, increasing magnetic induction by 0.02-0.04 T and the relative peak magnetic permeability μ _{1.5 / 50} for 400-600 units.

The following is an embodiment of the invention that does not exclude other variations within the scope of the claims.

Example

Smelted electrical isotropic steel with a ratio of aluminum and phosphorus (Al + P) = 0.265% with a carbon content of 0.034%; silicon 1.60%; aluminum 0.17%; phosphorus 0.095%; manganese 0.17%; sulfur 0.003%; nitrogen 0.005%; iron and unavoidable impurities are the rest. Steel was poured into slabs and hot rolled to a thickness of 2.2 mm. The hot-rolled strip was subjected to heat treatment in the normalization unit, pickling and cold rolling to a thickness of 0.50 mm with a degree of deformation of 77%.

Next, the cold-rolled strip was subjected to final heat treatment in a continuous annealing unit.

Implementation options for the production of highly permeable electrical isotropic steel in a thickness of 0.50 mm with different contents of silicon, aluminum and phosphorus are shown in table 1.

Table 1. Technological processing parameters and magnetic properties of highly permeable electrical isotropic steel No. p / p The content of elements,% The degree of deformation during cold rolling,% Magnetic properties Si Al P Al + P ΔP _{1.5 / 50} ,% B ₂₅₀₀ , T µ _{1,5 / 50} one 0.10 0.10 0.26 0.36 70.0 3.0 1.70 3120 2 0.16 0.15 0.24 0.39 75.0 3.0 1,69 2930 3 0.21 0.23 0.27 0.50 80.0 4.0 1.68 2845 four 0.94 0.18 0.18 0.36 78.0 5,0 1,67 2615 5 1.28 0.20 0.14 0.34 80.0 5,0 1,66 2525 6 1,60 0.17 0,095 0.265 77.0 6.0 1.65 2310 7 2.15 0.10 0.06 0.16 74.0 7.0 1,64 2265 8 2,50 0.23 0.27 0.50 71.0 7.0 1,63 2150 9* 0.09 0.08 0.27 0.35 69.0 9.0 1.68 2510 10* 0.20 0.23 0.28 0.51 80.0 11.0 1.65 2350 eleven* 0.91 0.25 0.17 0.42 75.0 12.0 1,63 2130 12* 1,62 0.19 0.08 0.27 60.0 11.0 1,62 1860 13* 2.17 0.11 0.06 0.17 65.0 12.0 1,60 1745 fourteen** 2,50 0.24 0.28 0.52 81.0 - - - Note: * - processing without taking into account the operational parameters of steel production; ** - brittle metal, not processed

Claims (1)

A method for the production of highly permeable electrotechnical isotropic steel, including smelting, steel casting, hot rolling, heat treatment of a hot rolled strip, etching, cold rolling and heat treatment of a cold rolled strip, characterized in that the steel is melted at the following content of components, wt.%:
carbon no more than 0,04 silicon 0.10-2.50 aluminum 0.10-0.23 phosphorus 0.06-0.27 manganese no more than 0.40 sulfur no more than 0,010 nitrogen no more than 0,008 iron and inevitable impurities rest
and at a ratio of 0.16 ≤ Al + P ≤ 0.50, where Al is the aluminum content in steel, wt.%, P is the phosphorus content in steel, wt.%, and the strip obtained after etching is subjected to cold rolling at a degree of deformation, equal to 70-80%.