SU1101458A1 - Method for producing anizotropic electrical steel - Google Patents

Abstract

THE METHOD OF MANUFACTURE OF ANISOTROPICAL ELECTROTECHNICAL STEEL, including smelting, casting, hot rolling, cooling, pickling, single or multiple cold rolling with intermediate annealing, decarburizing and final annealing, are distinguished by and. In order to increase the magnetic properties while simplifying the method of steel production, cooling after hot rolling is carried out at a speed of up to 800-870 ° C with further cooling to a temperature not higher than 600 ° C at a rate of 15- 100 ° C / s. i

Description

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00 The invention relates to ferrous metallurgy, in particular, to the production of anisotropic electrical steel used for the manufacture of magnetic circuits of electrical apparatus. In order to ensure high technical and economic indicators of electrical equipment, such steel should have low specific losses, high magnetic permeability. These characteristics of the steel are mainly determined by the degree of perfection of the (110) (001) crystallographic texture, with its increasing the values of these characteristics are improved. There are known methods for producing anisotropic electrical steel (which determine the deformation modes and the temperature-speed modes of the hot rolling. A known method of producing an electrical sheet, according to which, in order to increase the magnetic properties of steel, after hot rolling, additional hot treatment is carried out with a reduction rate of 3–20% at 400–900 ° C for 2–20. Such treatment improves the magnetic properties, but complicates the technology and significantly increases the cost of steel. The closest to the invention to the technical essence and the achieved results is a method including the smelting and casting of metal, hot rolling of ingots on the slab heating, rolling on a strip, etching, single or multiple cold rolling with intermediate heat treatments and final annealing. To form the inhibitor phase of the required size of the structure and texture of the strips and to obtain high magnetic properties of the steel, slabs are heated up to 1170–1220 ° C at a rate of 6–10 ° C / min, cooled in air to 1120 ° C at a rate of 12–20 ° C / min, heating to 1370-1440 ° C at a rate of 2.5-4 ° C / min, rolling to an intermediate thickness with a relative reduction of 75-90%, with simultaneous cooling to 1000-1100 ° C at a speed of 90120 ° C / min, heating of intermediate rolls up to 1070-1170 ° С at a rate of 9О-120 С / min, final rolling with a relative reduction of 85-95% with one temporal cooling to a temperature not lower than 900 ° C at a speed of 200-300 ° e / min 2. The disadvantage of the known method is its complexity, which consists in heating the metal three times, which, due to its abundant temperature-time parameters, causes implementation, significantly increasing the cost of steel. At the same time, the magnetic properties of the steel are low, in particular, the specific losses for strips with a thickness of 0.5 mm are 1.25-1.5 W / kg for 0.35 mm - 0.95 - 1-10 W / kg. The scope of the invention is to increase the magnetic properties while simplifying the method for producing steel. This goal is achieved by the fact that according to the method of production of electrical steel, including smelting, casting, hot rolling, cooling, pickling, single or multiple cold rolling with intermediate annealing, decarburizing and final annealing, cooling after hot rolling is carried out at a speed of up to 800 -870s with further cooling to a temperature not higher with a speed of 15t-100 ° C / s. Typically, metal for making anisotropic electrical steels contains 0.030-0.050% carbon and up to 3.5% silicon. Despite the fact that silicon is an element that strongly narrows the Y region, when the metal is heated above 780 ° C, the A-Jf transformation occurs in its microvolumes. The amount of f-phase increases to 1150 ° C and reaches 2030%. When the metal is cooled, the amount of the β phase decreases due to its decomposition with the formation of a carbon-containing phase. The type and amount of this phase depends on the conditions and rate of cooling of the metal on the temperature of the α-phase. Studies have shown that to obtain a high level of magnetic properties, it is necessary to have in the hot rolled strip a fully recrystallized structure and 5-10% of a solid carbon-containing phase such as Martensite or Beynit. This ensures the formation of optimal parameters of the inhibitory phase, texture-and-structure of the primary recrystallization. The proposed cooling modes for the strip after hot rolling provide a fully recrystallized metal with 5-10% of the solid carbon-containing phase. Cooling at a rate from the end of rolling temperature to 800-87 ° С ensures complete recrystallization in the metal, deformed during hot rolling, and obtaining a structure of uniform grain size. When cooled at a rate of less than 1 ° C / s, the growth of some grains starts at the expense of others, which causes a deterioration in the magnetic properties of the finished steel. The maximum cooling rate, the crtor ensures complete recrystallization of lG ° C / c. When cooled at a higher rate, the recrystallization process does not completely go through, which also causes a deterioration of the magnetic properties. The required amount of phase, from which 5-10% of the solid carbon-containing phase is separated, exists at 800-870 ° C. The cooling rate of 15-i is 100 ° C / s, from 800-870 ° C to temperatures not higher than 5 to obtain 10% solid carbonaceous phase type Beynit, Martensite. When cooled at a rate of less than 15 C / s, a less efficient carbon phase such as Trostit, Sorbit, and Perlite is formed. Cooling at a rate higher than technically difficult to do, causes an increase in the brittleness of the metal at the subsequent redistribution and does not contribute to a further increase in the level of magnetic properties. When the metal is cooled to temperatures not higher than b00 ° C, changes occur in the amount and type of carbon-containing phase but occur. Cooling to a temp, ratur above 600 ° C causes obtaining less effective Trostite, Sorbitol, Perlite. - Apply p. Steel of composition,%: carbon 0.040; silicon 3.0; 0.018; nitrogen 0,002.

Table C would be subjected to hot rolling from 1320 ° C to a 2.2 mm strip thickness with a rolling end temperature of 9501000 ° C. The cooling modes for the end rolling temperature are given in Table 1; magnetic properties — in Table 2. After hot pickled strips were etched in hot 50% hydrochloric acid, cold rolling to tol followed (skins 0.35 and 0.30 mm, decarbonised (extraordinary annealing in wet) (TR. + 2 (HS) nitrogen-hydrogen atmosphere at C for 5 min and high-temperature annealing at 1150 ° C for 5 h. Table 2 shows that the specific loss in STYLES obtained by the proposed method is less than even in steel obtained by The reduction in the number of operations in the manufacture of electrical steel simplifies the production process, which ultimately This leads to a reduction in the cost of the hoist. The economic effect of introducing the invention is 185 thousand rubles. The proposed method will increase the annual output of 3406 steel by 2.8%, which with an annual output of 180 thousand tons of electrical steel will be 5 thousand tons.

5 5 5 1

60 60 60 60 60

10 5 5 15 100

400 400 600 200 400 400 350

T. a b l and c a

Claims (1)

METHOD FOR PRODUCING ANISOTROPIC ELECTRICAL STEEL, including smelting, casting, hot rolling, cooling, pickling, single or multiple cold rolling with intermediate annealing, decarburization and final annealing, characterized in that, in order to increase the magnetic properties of the steel while simplifying the steel cooling after hot rolling is carried out at a speed of 1-10 ° C / s to 800-870 ° C with further cooling to a temperature not higher than 600 ° C at a speed of 15-100 ° C / s. - '' in $ ω