SU1717649A1 - Process for producing cold-rolled isotropic electrical steel - Google Patents

Abstract

The invention relates to metallurgy and can be used in the production of isotropic electrical steel. The purpose of the invention is to improve the ductility and improve the magnetic properties of steel. The method of production of electrical steel containing 3.3-3.7% silicon and 0.3-0.7% aluminum includes hot rolling on a tackle with a thickness of 1.6-2.2 mm in the temperature range of 800-950 ° C. C, normalization of hot rolled strip, cold rolling and final heat treatment. The coiling temperature after bitter rolling is established depending on the ratio of the silicon and aluminum content, the thickness of the hot rolled strip and the temperature of the end of the hot rolling, and the normalization temperature - depending on the ratio of the silicon content and. aluminum, the thickness of hot rolled steel and coiling temperature according to certain ratios of m. 2 tab. cl

Description

The invention relates to ferrous metallurgy, more specifically to the production of cold rolled isotropic electrical steel.

The structure of hot rolled rolled steel made of tropic electrical steel, while keeping the sum of the main alloying elements of more than 3.2%, is an important characteristic that determines its magnetic force and the possibility of further processing, as well as the level of magnetic components of the finished steel.

Formation of a given structure; hot-rolled rolled strip is largely determined by the influence of chemical compositions, tempera; torsional deformation conditions of hot rolling, the thickness of the rolled and the subsequent normalization treatment.

A known method for the production of isotropic electrical steel, according to which the use of slabs made of electrical steel, containing,%: Si 40; AI 1.0. After hot rolling, the strip is wound at 750-1000 ° C and subjected to recrystallization in coils due to its own heat. Then the strip is subjected to pickling, cold rolling and final annealing.

A disadvantage of the known technical solution is that, in the production of upgraded isotropic steel, it cannot provide the optimal structure of a hot rolled rolled steel that has undergone normalization.

Xi

processing without taking into account chemical composition in the range of specified coiling temperatures.

Closest to the invention is a method for the production of isotropic electrical steel, including hot rolling a steel containing,%: silicon, 2.6-3.3; aluminum 0.3-0.8, into a strip with a thickness of 1.9-2.5 mm, winding of the strips at temperatures determined depending on the silicon content and the thickness of the rolled core by the ratio:

Themes 650 + (100 ± 20) 9.4 (3.16 - Si) (H -2.0), 8 (H - 2.0) + 0.94,. where SI is the silicon content; H is the thickness of the strip after hot rolling, cold rolling of the strips with preliminary annealing of the rolled stock or without it, and final heat treatment.

The disadvantage of this method is that the ratio presented in it reflects only the mutual influence of the temperature of the end of rolling, the thickness of the rolled stock and the silicon content without taking into account the existing strong interaction between the coiling temperature and the temperature of the subsequent normalization treatment. This leads to an uncontrollable recrystallization process in the normalization treatment of a hot rolled rolled stock and, as a result, does not allow for an optimal structure to obtain the necessary ductility in a cold state and improve the magnetic properties of the finished steel.

The purpose of the invention is to increase the plasticity and improve the magnetic properties.

The goal is achieved by the fact that according to the method of production of cold-rolled isotropic electrical steel containing,%: silicon 3.3-3.7; aluminum 0.3-0.7, which includes hot rolling on a rolled-wire with a thickness of 1.6-2.2 mm in the temperature range of 800; -9500С, winding of strips at a temperature determined depending on the silicon content and thickness of cold rolling and final heat treatment, the coiling temperature additionally depends on the aluminum content and the temperature of the end of the hot rolling by the ratio

(TKP-870)

Csi

CAI

8.0

3.25

X

(H-1.9) IH-1.91

after winding, normalization is carried out at a temperature determined by the ratio:

Tn (930 - 950) + 9 ---- 50- - LAI1.0

T

cm

536 1: - 21.7J

33 Csi

CAI

15

20

25

thirty

35

40

45

50

55

where Tem - optimal coiling temperature, ° C;

TCP - the end of rolling temperature, ° 0;

Tn optimal normalization temperature, ° C;

GSI — silicon concentration, May.%;

CAI - aluminum concentration, wt.%;

H is the strip thickness after hot rolling, mm.

When implementing the proposed method, it is possible to achieve a positive effect by increasing the plasticity level of the normalized hot rolled rolled stock and creating a favorable texture (100), leading to an improvement in the magnetic properties of the finished product.

Under laboratory conditions, the dependences of the mechanical properties of a hot rolled strip after normalization treatment — hardness, ductility (bends), tensile strength, yield strength, relative elongation, impact strength, structural characteristics — depth of the recrystallized zone and size in the recrystallization zone — are examined. , the magnetic properties of the finished steel - specific losses and induction from technological factors: the content of silicon and aluminum, the temperature of the end of rolling, the thickness of the mountains of the rolled strip temperature of sm ki and normalizing temperature and the dependence of the mechanical properties of hot rolled strip from structural characteristics.

The chemical composition of electrical steel is given in table 1.

Three melts of electrical isotropic steel with the chemical composition indicated in Table 1 are rolled in a hot rolling mill from slabs with a thickness of 150 mm to a strip with a thickness of 1.6, 1.9, and 2.2 mm. The heating temperature of the slab is 1180-1200 ° С. The temperature of the end of hot rolling is 800-950 ° C. The coiling temperature is changed by adjusting the supply of cooling water to the outlet roller table. After rolling the hot-rolled strip, it is subjected to normalized treatment. Further processing of the metal is carried out under industrial conditions according to the following technological scheme: etching, single cold rolling to a thickness of 0.5 mm, decarburization-recrystallization annealing at 950-980 ° C.

The parameters and ratios indicated in the proposed method allow to provide conditions for increasing the plasticity level of a normalized hot rolled rolled strip of 1.5.5 bends by creating a uniform fine-grained recrystallized structure for the entire thickness of the rolled strip with an average grain size of 70-80 microns and resulting improving the magnetic properties of the finished steel.

The experience of processing high-silicon steel shows that a sufficiently complete characteristic of ductility and manufacturability of the rolled stock is the number of bends. A metal having less than 1.5 bends cannot be processed without additional heating.

The results of steel processing are given in table 2.

The technical and economic advantages of the proposed method for the production of cold rolled isotropic electrical steel is that & n allows, to improve the manufacturability of hot rolled high-alloyed steel, which passed the normalization annealing and to produce steel with a high level of magnetic properties.

Claims (1)

The invention The method of production of cold-rolled isotropic electrical steel, containing mainly 3, 7% silicon and 0.3-0.7% aluminum, including hot rolling on rolled up 1.6-2.2 mm in the temperature range 800--950 ° C. coiling of the strip at a temperature determined depending on the silicon content and the thickness of the hot rolled strip, cold rolling and final heat treatment, characterized in that, in order to increase ductility and improve the magnetic properties, the coiling temperature additionally depends on the aluminum content and temperature end of hot rolling by ratio Csi cai -8,0 3.25 Themes 1.300 (TKP - 870) „„ X x (H-1.9) after winding, normalization is carried out at a temperature determined by the ratio T (930 - 950) + x T, CAI 1.6 cm 536 33 GSJ CAI 21.7 where the is the optimal coiling temperature, ° C; . TKp - the end of rolling temperature, ° C; Tn - optimal normalization temperature, ° С; Csi - silicon concentration, wt.%; CAI - aluminum concentration, wt.%; H — strip width after hot rolling, mm. Table 1 Continued tabl, 1 one 5 1  , Ml «, 71 4,71 4,71, 7t, 7t« i. , 71 , 71 8,10 8.10 8.10 -8.10 8.10 8.10 8.10 8.10 8.10 12.33 12.33 12.33 12.33 12.33 12.33 V 12.33 12.33 12.33 12.5 ft.3 , 6 .6 6, 9 ,9 ,9 2.2 2.2 2.2 1.6 .1,6, 1.6 1.9 1.9 1.9 2.2 2.2 2.2 .6 : t ,9 ,9 ,9 2.2 2.2 2.2 2.5 I, 1 950 870 800 950 870 800 950 870 800 950 870 800 950 870 800 950 870 800 950 870 800 950 870 800 950 870 800 750 650 550 650 650 650 550 650 750 650 650650 650 650 650 650 650 650 550 650 750 650 650 650 750 650 550 980 980 980 990 990 990 1050 99 940 1030 1030 1030 1030 1030 1030 1040 1040 1040 1050 1050 1050 1010 1010 1010 920 980 1030 Formation of increased brittleness T a b l i 5.0 6.1 7.5 oh oh 3.5 3.8 1.5 3.4 3.5 M 45 5.0 2.0 2.1 2.5 1.5 1.8 2.0 , 7 .6 ,five ,eight ,9 ,about ,one ,eight , 6 0.5 2.81 2.82 2.84 2, 2.82 2.83 2.80 2.8V 2.85 2.79 2 h 2.78 2.79 2.77 2.78 2.75 2.79 2.80 2.70 2.72 2.73 2.72 2.73 2.74 2.75 2.74 2.71