RU2098493C1 - Process of production of anisotropic electrical sheet steel - Google Patents

Abstract

FIELD: production of anisotropic electrical sheet steel with especially low re-magnetization losses. SUBSTANCE: proposed process includes melting of steel by nitride variant with alloying with aluminium, copper and manganese, double cold rolling with decarbonization annealing in intermediate thickness, low-temperature annealing in continuous or bell-type furnace. Dressing of stripes is conducted after low-temperature annealing. As result of dressing of annealed stripes there takes place increase of inhibition phase thanks to more intensive release of copper-carrying phase from solid solution and decrease of planeness of stripes before deposition of protective coat which creates favorable preconditions for formation of optimal structure and texture during secondary recrystallization and obtainment of homogeneous priming layer in process of high-temperature annealing which in its turn makes it possible to diminish maximal watt specific losses by 5-6% and increase output from first class surface by 4-5 times. EFFECT: formation of optimal structure and texture, decreased specific losses. 1 tbl

Description

 The invention relates to ferrous metallurgy, in particular to the production of anisotropic electrical sheet steel used for the manufacture of magnetic circuits with low losses of electrical energy for magnetization reversal.

 Known methods for the production of anisotropic electrical thin-sheet steel, including smelting steel alloyed with aluminum, copper, manganese and titanium, double cold rolling of strips with decarburization annealing in an intermediate thickness and annealing in a final thickness before applying a protective coating (1-4).

The closest (prototype) is the method (4), including the smelting of steel chemical. composition, wt. carbon 0.035-0.040; silicon 2.80-3.20; manganese 0.18-0.27; aluminum 0.013-0.17; copper 0.50-0.60; nitrogen 0.006-0.015, hot rolling of strips to a thickness of 2.5 mm, etching, and the first cold rolling to a thickness of 0.70 mm, decarburization annealing in a humidified nitrogen-hydrogen atmosphere, the second cold rolling on a 20-roll mill to a nominal thickness of 0, 27 mm, degreasing and heat treatment in a continuous furnace at a temperature of 550-590 ^o C, applying a protective coating, high-temperature annealing in a bell furnace, straightening annealing and applying an insulating coating.

ρ 0,5•10¹³-1,0•10¹⁴ шт/см, что позволяет достигнуть высокого выхода стали высшей категории качества по магнитным свойствам.The disadvantage of this method is the low yield of lots of steel of the highest quality category: grade 5409 according to GOST 21427-1-83 is not more than 0.4% yield of steel of the 1st class of surface according to TU 14-106-416-92 is not more than 5%
Studies of the fine structure of the metal of various melts melted and formed by known methods have shown that the size and density (P) of the phases
inhibitors that stabilize the primary recrystallization matrix during heating and determine the predominant growth of grains with a rib texture (110) [001] during secondary recrystallization vary widely α 30-50

ρ 0.5 • 10 ¹³ -1.0 • 10 ¹⁴ pcs / cm, which allows to achieve a high yield of steel of the highest quality category in magnetic properties.

 In the production of anisotropic sheet steel according to known methods, cold-rolled strips in a final thickness before applying a protective coating have an increased local leakage. This is due to the fact that the second cold rolling of metal with a relative compression of more than 60% having an increased deformation resistance is carried out mainly on mills with a small diameter of the work rolls, and a decarburized strip is used as the initial billet, on the surface of which there is always uneven length and width of the strip the film is mainly made of silicon oxides.

 In addition, the cross sections of the original strip in most cases are asymmetric due to the uneven length of the barrel of wear of the work rolls during hot and cold rolling of high silicon steel, which makes it difficult to obtain flat strips.

 Local non-flatness is not corrected during low-temperature heat treatment in a continuous furnace and prevents the application of an even layer of protective coating, obtaining a coiling density of coils before annealing in a bell furnace, which is one of the reasons for the low yield of finished steel with a class 1 surface.

 The described disadvantages are inherent in other known methods for the production of anisotropic electrical sheet steel with decarburization in an intermediate thickness (2-4).

где
Δh сумма предельных отклонений по толщине, мм;
h номинальная толщина готовой стали, мм;
Исследования показали, что дрессировка отожженных полос стимулирует выделение из твердого раствора медьсодержащих фаз Cu₅Si; CuMnO₄, что при последующем нагреве увеличивает суммарную плотность фаз-ингибиторов на этапе первичной рекристаллизации с (0,5-2,0)•10¹³ до 3,0•10¹³-1,0•10¹⁴ /см³ и обеспечивает за счет этого улучшение магнитных свойств.The elimination of these drawbacks is achieved by the fact that in the method, including double cold rolling with decarburization annealing in the intermediate thickness, the second cold rolling is performed at the nominal thickness with a plus tolerance equal to the sum of the maximum deviations in thickness, and before applying the protective coating, the annealed strips are trained with a relative compression E, determined by the formula:

Where
Δh is the sum of the maximum deviations in thickness, mm;
h is the nominal thickness of the finished steel, mm;
Studies have shown that the training of annealed bands stimulates the release of copper-containing phases Cu ₅ Si from a solid solution; CuMnO ₄ , which upon subsequent heating increases the total density of phase inhibitors at the stage of primary recrystallization from (0.5-2.0) • 10 ¹³ to 3.0 • 10 ¹³ -1.0 • 10 ¹⁴ / cm ³ and ensures due to this improvement in magnetic properties.

 The use of training reduces one and a half to two times the amount of flatness of the strips before applying the protective coating, increases the uniformity of the soil layer of silicon, magnesium and iron oxides formed during high-temperature annealing in a tightly wound roll, and the surface quality of the finished steel.

According to the proposed technology, the composition is smelted, wt. carbon 0.030-0.045; silicon 2.80-3.20; manganese 0.18-0.30; aluminum 0.013-0.025; copper 0.40-0.60; nitrogen 0.006-0.015; the rest is iron and inevitable impurities. Continuously cast slabs are rolled onto cold-rolled strips 0.70 mm thick, decarburized in a continuous furnace in a humidified nitrogen-hydrogen mixture and re-rolled to a nominal thickness of 0.23 and 0.27 mm with a positive tolerance of 0.02 mm, then annealed in a bell or continuous furnace at a temperature of 550-800 ^o C. After annealing, the strips are trained with a relative compression of 8.7-10.5% and a protective coating of low-hydrated magnesium oxide is applied. The tightly wound rolls are annealed at a temperature of 1150 ^o C in a bell furnace in dry hydrogen and a nitrogen-hydrogen mixture. After high-temperature annealing, an electrically insulating magnesium phosphate coating is applied to the strips, followed by rectifying annealing in a continuous furnace.

 The results obtained in comparison with the known method i.e. without training are presented in the table.

 The table shows that the proposed method for the production of thin strips of anisotropic electrical steel can reduce the maximum specific cotton losses by 5-6% and increase the yield of steel with a class 1 surface according to TU 14-106-416-92 by 4-5 times.

Claims (1)

 A method for the production of anisotropic electrical steel, including the smelting of steel composition, wt. Carbon 0.030 0.045
Silicon 2.80 3.30
Manganese 0.15 0.30
Aluminum 0.013 0.025
Copper 0.40 0.60
Nitrogen 0.006 0.015
Iron Else
and unavoidable impurities, hot rolling, etching, double cold rolling with decarburization annealing in the intermediate thickness, annealing in a bell or feed furnace, applying a protective coating, high-temperature annealing in dry hydrogen or a nitrogen-hydrogen mixture, straightening annealing and applying an insulating coating, characterized in that the second cold rolling is carried out at a nominal thickness with a positive tolerance equal to the sum of the maximum deviations in thickness, and before applying the protective coating, produce essirovku strips annealed at 550 ^o 800 C with a relative compression E, defined by the formula

where Δh is the sum of the maximum deviations in thickness, mm;
h is the nominal thickness of the finished steel, mm

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