ORIENTED SILICON STEEL AND MANUFACTURING METHOD THEREFOR

Description

TECHNICAL FIELD

[0001] The present invention relates to an oriented silicon steel and manufacturing method thereof, in particular to an oriented silicon steel having low magnetostriction and manufacturing method thereof.

BACKGROUND

[0002] Oriented silicon steel is a soft magnetic material characterized by sharp {110}<001> orientation (i.e., Gaussian grains). Oriented silicon steel, which is an important functional material, is commonly used in the manufacture of transformer cores.

[0003] In the prior art, according to the different magnetic properties and Gaussian grain orientation degree, oriented silicon steel can be divided into common oriented silicon steel (abbreviated as CGO) and high magnetic oriented silicon steel (abbreviated as Hi-B); compared with CGO silicon steel, Hi-B silicon steel has lower iron loss, higher magnetic induction intensity, and smaller magnetostriction. In recent years, with the increasing attention to transformer noise performance, transformer noise performance has become a key indicator for manufacturers. Since the magnetostriction of oriented silicon steel has a decisive influence on the noise performance of transformers, oriented silicon steel with low magnetostriction has become a research hotspot.

[0004] In the production process of the oriented silicon steel, the prior art mainly reduces the magnetostriction of the oriented silicon steel by the following three technical routes: 1) increasing the Gaussian grain orientation degree of the oriented silicon steel product; 2) decreasing the thickness of the oriented silicon steel product; and 3) applying a high tensile coating. All these three technical routes can reduce the magnetostriction of oriented silicon steel.

[0005] CN111748731A (disclosed on Oct. 9, 2020, "Oriented silicon steel with low magnetostriction and manufacturing method thereof") produces preferred grain orientation (magnetic domain structure rearrangement) triggered by a portion of magnetic inhomogeneity due to partly sequential structural arrangement by hot stretching and magnetic annealing of a silicon steel substrate under specific conditions, so that the unidirectional magnetic anisotropy along the rolling direction is increased (i.e., the volume of the 180° magnetic domain wall is increased, and the volume of the 90° magnetic domain wall is decreased), which reduces the volume of the 90° magnetic domains of the oriented silicon steel product, and thus reduces the magnetostriction of the oriented silicon steel, which in turn reduces the overall noise level of the transformer. The application performed magnetic annealing under the following conditions: a magnetic annealing temperature of 750-200°C, a magnetic field oriented in the direction of rolling or transverse, and a pulsed field (50ms, 1-10 Hz) with a magnitude of 2500 A/m DC magnetic field + 50,000 A/m short-time pulsed magnetic field. The resulting oriented silicon steel product has an L_vA(17/50)<55 dB(A).

[0006] CN105220071A (disclosed on Jan. 6, 2016, "Oriented silicon steel with low noise characteristic and manufacturing method thereof") discloses an oriented silicon steel having 0.1%≤Cu≤0.5% and 0.01%≤S≤0.05% in the oriented silicon steel substrate, and the atomic ratio Cu/S satisfies: 5≤Cu/S≤10. During the manufacturing process of the oriented silicon steel, the coating tension on the steel surface, and the grain size of the product are strictly controlled. The L_vA(17) of the resulting oriented silicon steel product is less than 55 dB(A), and the vibration generated by the core of the transformer made of this oriented silicon steel is small, so that the overall noise level of the transformer is reduced.

[0007] CN107881411A (disclosed on April 6, 2018, "Silicon steel product with low iron loss for low-noise transformer, and manufacturing method thereof") discloses a low-iron-loss and low-noise oriented silicon steel. The application reduces iron loss and reduces magnetostriction/reduces noise by strictly controlling the vertical reflectivity R of the magnesium silicate bottom layer of the oriented silicon steel substrate to visible light to 40-60%, while ensuring that the magnesium silicate bottom layer has a uniform brightness. The vibration noise of magnetostriction of the final product is less than 60 dB(A), which is particularly suitable for transformers.

[0008] It can be seen that the magnetostriction can be reduced to some extent by controlling both the 90° magnetic domain distribution and the coating tension level. However, both of these methods require the use of additional external equipment or conditions to reduce the magnetostriction, and the reduction magnitude in magnetostriction is not significant. For example, although in CN111748731A, affecting the 90° magnetic domains by adding a magnetic field can increase the volume of the 180° magnetic domain wall, the reduction magnitude of the magnetostriction by the externally applied conditions at a later stage is relatively limited if the Gaussian texture of the oriented silicon steel substrate itself is not sharp enough. In addition, the method of refining the magnetic domains by increasing the coating tension has the same problem, and the method also has very high requirements on the coating properties. In addition, in some prior art, the magnetostriction can be reduced to some extent by reducing the thickness of the silicon steel sheet. However, due to the high silicon content of silicon steel, rolling the silicon steel to a thinner thickness would be more difficult and also result in increased costs.

[0009] Accordingly, the prior art for reducing magnetostriction by increasing the coating tension and reducing the thickness of the silicon steel have significant limitations. In contrast, by improving the Gaussian grain orientation degree of the oriented silicon steel itself (e.g., by optimizing the chemical composition and adjusting the production process to improve the Gaussian grain orientation degree of the oriented silicon steel product), i.e., by lowering the deviation angle of the Gaussian grains, thereby increasing the magnetic induction intensity, it is possible to fundamentally reduce the magnetostriction of the oriented silicon steel. In addition, in the context of the "carbon peaking and carbon neutrality" strategic objective, energy saving and environmental protection is also one of the focuses of the current production process. How to ensure the high quality and stable production of oriented silicon steel under the premise of reducing energy consumption will become one of the important R&D direction of oriented silicon steel.

[0010] Based on the above reasons, the present inventor expects to develop a new type of oriented silicon steel with low magnetostriction and a manufacturing method thereof, which can essentially improve the magnetic induction intensity of the oriented silicon steel and reduce the magnetostriction of the oriented silicon steel (by lowering the deviation angle of the Gaussian grains) on the basis of a green and consumption-reducing production process through the high-level design of the chemical composition of the oriented silicon steel and the rational optimization of the production process. This enables a high level of matching between high magnetic induction intensity and low magnetostriction of the oriented silicon steel.

SUMMARY

[0011] An objective of the present invention is to provide an oriented silicon steel and a manufacturing method thereof. The oriented silicon steel has an excellent matching of magnetic properties (especially in terms of high magnetic induction intensity and low magnetostriction), while at the same time the consumption of energy media in the production process is substantially reduced.

[0012] The first aspect of the present invention provides an oriented silicon steel, comprising, in addition to 90% or more of Fe and inevitable impurities, the following components in percentage by mass:
C: 0.020-0.080%, Si: 2.00-4.50%, Mn: 0.01-0.10%, S≤0.005%, acid soluble aluminum Als: 0.010-0.040%, N: 0.002-0.015%, Nb: 0.006-0.120%, and at least one selected from P: 0.01-0.10%, Sn: 0.01-0.30%, and Cu: 0.01-0.50%.

[0013] Preferably, the oriented silicon steel comprises the following components in percentage by mass:
C: 0.020-0.080%, Si: 2.00-4.50%, Mn: 0.01-0.10%, S≤0.005%, acid soluble aluminum Als: 0.010-0.040%, N: 0.002-0.015%, Nb: 0.006-0.120%, and at least one selected from P: 0.01-0.10%, Sn: 0.01-0.30%, and Cu: 0.01-0.50%; the balance of Fe and inevitable impurities.

[0014] Preferably, the oriented silicon steel has a thickness of 0.15-0.30 mm

[0015] Preferably, the oriented silicon steel has a magnetic induction intensity of B8>1.95 T and a magnetostrictive vibration velocity sound pressure level of L_vA <50 dB(A).

[0016] Another aspect of the present invention provides a manufacturing method for the above oriented silicon steel, comprising the following steps:

1) Smelting and casting a molten steel to produce a slab;

2) Heating the slab;

3) Hot rolling, including roughing rolling, coiling and holding and finishing rolling;

4) Cold rolling;

5) Decarburizing annealing;

6) Nitriding;

7) Applying an annealing separator;

8) High-temperature annealing;

9) Applying an insulation coating and performing scoring to produce an oriented silicon steel.

[0017] Preferably, in step 1), a thickness of the slab is 180-250 mm.

[0018] Preferably, in step 2), a heating temperature of the slab is 900-1150°C.

[0019] The present application uses an post-inhibitor process that performs nitriding treatment, so that the content of inhibitor elements in the slab is relatively low. The heating temperature in step 2) is conducive to energy consumption reduction and obtaining sufficient inhibitor at the same time. When the heating temperature of the slab is lower than 900°C, the inhibitor elements cannot be effectively solid-solutionized; when the heating temperature of the slab is higher than 1150°C, it will increase the energy consumption and the heat load of the heating furnace. Therefore, the heating temperature of the slab in step 2) is preferably controlled to be 900-1150°C.

[0020] Preferably, a thickness of the intermediate slab at the end of rough rolling is 35-50 mm

[0021] Preferably, in step 3), an end temperature of rough rolling is higher than 950°C, a coiling temperature is 800-1050°C, a coiling time is 30-200s, and an initial temperature of finishing rolling is lower than 1050°C.

[0022] The present application sets an end temperature of rough rolling to be higher than 950°C, which can ensure that a coiling temperature is 800-1050°C, a coiling time is 30-200s, and an initial temperature of subsequent finishing rolling is lower than 1050°C. At this coiling temperature, the layers of the hot-rolled plate themselves heat each other during the post-coiling and holding process, so there is no need for additional heating; in addition, the coiling between rough rolling and finishing rolling enable a more thorough recrystallization of the hot-rolled plate structure, and at the same time can precipitate part of the inhibitors dispersively. When the coiling temperature is lower than 800 °C or the coiling time is less than 30s, the desired recrystallization effect of the structure of the hot-rolled plate cannot be achieved; when the coiling temperature is higher than 1050°C or the coiling time is more than 200s, the grain organization of the intermediate slab and the precipitated inhibitors will be coarsened, which adversely affects the development of the subsequent structure and Gaussian texture. Therefore, it is preferred to set the temperature and/or time of the hot rolling process within the above range.

[0023] Preferably, after step 3) and before step 4), a normalizing annealing treatment is carried out, and the normalizing annealing temperature does not exceed 1000°C, preferably 800-1000°C, more preferably 800-980°C, and a normalizing annealing time is 20-200s.

[0024] By conducting extensive research, the present inventors have surprisingly found that normalizing annealing of hot-rolled plates at an annealing temperature of about 1100-1200°C, as routinely performed according to the present prior art, not only results in an oversized grain structure of the normalized plates, but also leads to coarsening of the inhibitors and ultimately deteriorates the magnetic properties.

[0025] By coiling and holding the rough-rolled plate at a temperature of 800-1050°C, it is possible to achieve a proportion of more than 10% for Gaussian grains with a deviation angle less than 3° in the steel plate after decarburizing annealing while no subsequent normalizing annealing treatment is performed or the normalizing annealing is performed at a normalizing annealing temperature of no more than 1000°C, thereby obtaining an oriented silicon steel product with desired Gaussian grain orientation degree and magnetic induction intensity. In contrast, the proportion of Gaussian grains with a deviation angle less than 3° in the steel plate after decarburizing annealing is significantly lower (i.e., significantly less than 10%) if the rough-rolled plate is not coiled and held, or if the normalizing annealing temperature after coiling and holding is higher than 1000°C.

[0026] Preferably, in step 4), a cold rolling reduction ratio is >80%.

[0027] Preferably, in step 5), a decarburizing annealing temperature is 800-900°C. When the decarburizing annealing temperature is lower than 800°C, the decarburization effect is not obvious; when the decarburizing annealing temperature is higher than 900°C, the primarily recrystallized grain is too coarse, affecting the secondary recrystallization.

[0028] Preferably, in step 5), a proportion of Gaussian grains with a deviation angle less than 3° in the steel plate after decarburizing annealing is more than 10%. The "proportion of Gaussian grains with a deviation angle less than 3° in the steel plate after decarburizing annealing" herein refers to the ratio (in %) of the number of Gaussian grains with a deviation angle less than 3° to the total number of Gaussian grains.

[0029] The "deviation angle" herein refers to the deviation angle of the Gaussian grain orientation. The deviation angle and ratio of Gaussian grains are observed and counted by a scanning electron microscope with an electron backscatter diffraction (EBSD) system.

[0030] Preferably, in step 6), an amount of nitriding is 50-280 ppm.

[0031] The present application uses a post-inhibitor process that performs nitriding treatment. In other words, a nitriding treatment must be performed prior to high-temperature annealing in order to form inhibitors that sufficient to inhibit growth of the primary recrystallized grain. When the amount of nitriding is lower than 50 ppm, the amount of inhibitor formation is insufficient; when the amount of nitriding is higher than 280 ppm, it will adversely affect the formation of the magnesium silicate bottom layer during the high-temperature annealing process. Based on these considerations, the amount of nitriding in step 6) of the present invention is strictly controlled to 50-280 ppm.

[0032] In step 7), the annealing separator may be an annealing separator commonly used in the art, preferably MgO.

[0033] Preferably, in step 8), an annealing temperature is 1100-1250°C and an annealing time is greater than 25 hours.

[0034] In step 9), the insulation coating may be formed using a coating fluid commonly used in the art, such as forming the insulation coating by applying a coating fluid comprising phosphate, colloidal silicon dioxide, and chromic anhydride; the scoring may be performed using a scoring method commonly used in the art, such as laser scoring, electrochemical scoring, tooth roller scoring, high-pressure water beam scoring, or the like.

[0035] Compared with the prior art, the oriented silicon steel and the manufacturing method thereof according to the present invention realize the following beneficial effects:
The present inventor found that the orientation degree of the Gaussian grain nuclei in the primary recrystallization has a decisive influence on the orientation degree of the Gaussian grain and magnetic induction intensity of the product through a large number of experiments. Therefore, the present inventor optimizes the design of the relevant process parameters, so that the proportion of Gaussian grains with a deviation angle less than3° in the steel plate after decarburizing annealing is more than 10%, thereby obtaining an oriented silicon steel product with desired Gaussian grain orientation degree and magnetic induction intensity.

[0036] The present invention obtains an oriented silicon steel with a matched high magnetic induction intensity and low magnetostriction under the premise of an environmental-friendly and consumption-reducing production process. The oriented silicon steel in the present invention has excellent magnetic properties (magnetic induction intensity of B8>1.95 T, magnetostrictive vibration velocity sound pressure level of L_vA<50 dB(A)), which has good economic benefits and application prospects.

DETAILED DESCRIPTION

[0037] By conducting extensive research, the present inventors surprisingly discovered that by designing the chemical composition of the oriented silicon steel above, an oriented silicon steel with excellent overall performance (especially high magnetic induction intensity and low magnetostriction) can be obtained. Specifically, the design principle of each aforementioned chemical elements is as follows. In the present application, the element contents are expressed in percentage by mass unless explicitly stated otherwise.

[0038] C: The addition of an appropriate amount of C ensures that an appropriate proportion of the γ phase is obtained in the hot rolling or normalizing process, which is conducive to the precipitation of fine dispersed inhibitors. When the C content in the steel is lower than 0.020%, the proportion of γ phase is low, which is unfavorable to the precipitation of the inhibitor; when the C content in the steel is higher than 0.080%, the decarburization cost is increased. Based on these considerations, the C content in the oriented silicon steel of the present invention is controlled to 0.020-0.080%, preferably 0.022-0.073%.

[0039] Si: Si is the main element to reduce iron loss. In order to ensure the quality of silicon steel product, the Si content in steel should not be too low or too high. When the Si content in the silicon steel is lower than 2.00%, it is difficult to obtain the desired low iron loss in the oriented silicon steel product; when the Si content in the steel is higher than 4.50%, it leads to difficulties in cold rolling and a reduction in the product yield. Based on these considerations, the Si content in the oriented silicon steel of the present invention is controlled to 2.00-4.50%, preferably 2.19-4.29%.

[0040] Mn: The addition of an appropriate amount of Mn can form a small amount of MnS auxiliary inhibitor in the continuous casting and hot rolling process, which can effectively improve the microstructure and rollability of the oriented silicon steel. In order to ensure the performance of the oriented silicon steel, the Mn content in steel must be strictly controlled. When the Mn content is less than 0.01%, it is detrimental to obtaining the desired microstructure and rollability of the silicon steel; when the Mn content is higher than 0.10%, the slab heating temperature will be significantly increased, and it is easy to form coarse MnS inhibitors. Based on these considerations, the Mn content in the oriented silicon steel of the present invention is controlled to 0.01-0.10%, preferably 0.01-0.09%.

[0041] S: S can form auxiliary inhibitors such as MnS and Cu₂S. However, it should be noted that the S content in steel should not be too high. When the S content in the steel is too high, it will significantly increase the slab heating temperature, which is not favorable to production. Based on these considerations, the S content in the oriented silicon steel of the present invention is controlled to S ≤ 0.005%, preferably ≤ 0.004%.

[0042] Acid soluble aluminum Als: Acid soluble aluminum Als is an important component in the formation of the main inhibitor AlN. When the acid soluble aluminum Als content in steel is lower than 0.010%, it will lead to insufficient inhibitor; when the acid soluble aluminum Als content in steel is higher than 0.040%, it will lead to coarse inhibitor AlN. Therefore, the acid soluble aluminum Als content in the silicon steel needs to be strictly controlled. Based on these considerations, the acid soluble aluminum Als content in the oriented silicon steel of the present invention is controlled to 0.010-0.040%, preferably 0.012-0.039%.

[0043] N: The addition of an appropriate amount of N can properly inhibit grain growth. The addition of N in silicon steel can cooperate with acid soluble aluminum Als to form AlN before nitriding, thereby effectively inhibiting the growth of the primary recrystallized grains. When the N content in the steel is lower than 0.002%, the growth of the primary recrystallized grains cannot be effectively inhibited; when the N content in the steel is higher than 0.015%, the difficulty of steelmaking will be significantly increased. Based on these considerations, the N content in the oriented silicon steel of the present invention is controlled to 0.002-0.015%, preferably 0.003-0.014%.

[0044] Nb: In order to reduce the slab heating temperature, the Mn and Cu contents are relatively low, but this leads to insufficient precipitation of MnS and Cu₂S. Therefore, in order to compensate for the lack of inhibition ability of the inhibitor, an appropriate amount of Nb is added into the silicon steel. Nb can form auxiliary inhibitor Nb (C, N), and play the role of auxiliary inhibitor. In addition, due to the relatively low solid solution temperature of Nb (C, N), it can also reduce the heating temperature of the slab. When the Nb content in the steel is lower than 0.006%, the inhibitor Nb (C, N) formed cannot fully realize the inhibitory effect; when the Nb content in the steel is higher than 0.120%, the occurrence of secondary recrystallization is hindered as the inhibitory effect is too strong. Based on these considerations, the Nb content in the oriented silicon steel of the present invention is controlled to 0.006-0.120%, preferably 0.006-0.118%.

[0045] P and Sn: P and Sn are both grain boundary segregation elements. The addition of an appropriate amount of P and Sn in silicon steel can act as auxiliary inhibitor. When the P and Sn contents in the steel are each lower than 0.01%, the auxiliary inhibitor effect cannot be fully realized; when the P and Sn contents in the steel are higher than 0.10% and 0.30%, respectively, the decarburization and nitriding will be adversely affected. Based on these considerations, the P content in the oriented silicon steel of the present invention is controlled to 0.01-0.10%, preferably 0.02-0.08%, and the Sn content is controlled to 0.01-0.30%, preferably 0.02-0.25%.

[0046] Cu: The addition of an appropriate amount of Cu in silicon steel can not only form auxiliary inhibitors such as Cu₂S, but also effectively expand the γ-phase region, thus facilitating the precipitation of other inhibitors. However, it should be noted that the Cu content in steel should not be too low or too high. When the Cu content in the silicon steel is lower than 0.01%, the above effect cannot be fully realized; when the Cu content in the silicon steel is higher than 0.50%, the production cost will be increased. Based on these considerations, the Cu content in the oriented silicon steel of the present invention is controlled to 0.01-0.50%, preferably 0.02-0.48%, for example 0.02-0.39%.

[0047] The oriented silicon steel and the manufacturing method thereof of the present invention will be further explained and illustrated below in connection with specific Examples. However, the following description is an illustrative description for explaining the present invention and is not intended to limit the technical scope of the present invention to the description.

Examples 1-12

[0048] The oriented silicon steel of Examples 1-12 of the present invention is manufactured by the following steps:

1) Smelting and casting a molten steel according to the composition shown in Table 1 below, producing a slab with a thickness of 180-250 mm.

2) Heating the slab at a temperature of 900-1150°C.

3) Rough rolling, coiling and holding and finishing rolling of the slab: an end temperature of rough rolling was higher than 950°C, a coiling temperature was 800-1050°C, a coiling time was 30-200s, and an initial temperature of finishing rolling was lower than 1050°C.

4) Cold rolling to a finished plate thickness of 0.15-0.30 mm, wherein a cold rolling reduction ratio was >80%.

5) Decarburizing annealing at a temperature of 800-900°C.

6) Nitriding, wherein the amount of nitriding was 50-280 ppm.

7) Applying an annealing separator.

8) High-temperature annealing, wherein an annealing temperature was 1100-1250°C and an annealing time was greater than 25 hours.

9) Applying an insulation coating and performing scoring to produce an oriented silicon steel with a thickness of 0.15-0.30 mm.

[0049] It should be noted that Examples other than Example 10 and Example 11 were also subjected to a normalizing annealing treatment (normalizing annealing temperature was not more than 1000°C, normalizing annealing time was 20-200s) between steps 3) and 4).

Comparative Examples 1-20

[0050] Comparative Examples 1-20 used similar process steps to manufacture the oriented silicon steel, wherein the Comparative Examples other than Comparative Example 16 were also subjected to a normalizing annealing treatment between steps 3) and 4). However, the chemical composition and the process parameters of the oriented silicon steel of Examples 1-12 satisfy the claimed scope of the present invention, whereas at least one of the chemical composition and/or the process parameters of Comparative Examples 1-20 does not satisfy the claimed scope of the present invention.

[0051] The chemical compositions of the oriented silicon steels of Examples 1-12 and Comparative Examples 1-20 are shown in Table 1.

Table 1 (wt%, the balance is Fe and inevitable impurities)

Number	C	Si	Mn	S	Als	N	Nb	P	Sn	Cu
Example 1	0.031	3.25	0.02	0.004	0.029	0.003	0.009	0.04	0.08	0.02
Example 2	0.052	3.51	0.04	0.004	0.027	0.006	0.011	0.08	0.15	-
Example 3	0.073	3.81	0.06	0.004	0.021	0.008	0.033	-	-	0.15
Example 4	0.066	3.03	0.08	0.004	0.018	0.011	0.062	0.06	-	-
Example 5	0.048	2.84	0.09	0.004	0.033	0.013	0.097	-	0.20	-
Example 6	0.022	2.19	0.01	0.004	0.036	0.014	0.118	-	0.25	0.18
Example 7	0.045	4.29	0.05	0.004	0.012	0.009	0.006	0.02	-	0.29
Example 8	0.037	3.28	0.08	0.004	0.039	0.007	0.088	-	0.02	0.39
Example 9	0.041	2.99	0.09	0.004	0.028	0.009	0.028	0.05	-
Example 10	0.033	3.27	0.08	0.004	0.033	0.006	0.055	-	0.17	-
Example 11	0.052	3.18	0.06	0.004	0.030	0.011	0.072	-	-	0.32
Example 12	0.051	3.16	0.05	0.004	0.029	0.010	0.061	0.03	0.012	0.48
Comparative Example 1	0.015	3.25	0.06	0.004	0.028	0.011	0.029	0.05	-	-
Comparative Example 2	0.038	1.5	0.02	0.004	0.029	0.011	0.033	0.05	0.15	-
Comparative Example 3	0.036	3.35	0.06	0.004	0.027	0.011	0.032	-	-	-
Comparative Example 4	0.033	3.45	0.06	0.004	0.006	0.010	0.045	-	0.26	0.18
Comparative Example 5	0.027	3.44	0.05	0.004	0.027	0.001	0.033	-	0.26	0.28
Comparative Example 6	0.038	3.65	0.04	0.004	0.033	0.012	0.004	0.07	-	-
Comparative Example 7	0.037	3.62	0.04	0.004	0.032	0.011	0.160	0.06	-	-
Comparative Example 8	0.032	3.6	0.18	0.004	0.036	0.011	0.028	-	0.21	-
Comparative Example 9	0.09	4.62	0.06	0.004	0.038	0.011	0.022	-	0.25	-
Comparative Example 10	0.033	3.4	0.06	0.004	0.045	0.019	0.031	0.09	-	0.28
Comparative Example 11	0.029	3.32	0.07	0.006	0.030	0.012	0.058	0.04	0.20	-
Comparative Example 12	0.036	3.13	0.08	0.004	0.026	0.011	0.062	0.06	-	-
Comparative Example 13	0.032	3.18	0.08	0.004	0.028	0.011	0.090	0.06	-	-
Comparative Example 14	0.04	3.14	0.07	0.004	0.029	0.010	0.082	-	0.09	-
Comparative Example 15	0.037	3.17	0.06	0.004	0.033	0.008	0.067	-	0.22	0.09
Comparative Example 16	0.032	3.28	0.08	0.004	0.035	0.006	0.089	-	0.14	-
Comparative Example 17	0.035	3.33	0.06	0.004	0.027	0.007	0.054	0.04	0.18	-
Comparative Example 18	0.037	3.45	0.07	0.004	0.032	0.012	0.048	0.05	-	-
Comparative Example 19	0.032	3.31	0.07	0.004	0.029	0.011	0.059	0.06	-	-
Comparative Example 20	0.033	3.30	0.07	0.004	0.031	0.011	0.049	0.06

[0052] Specific process parameters for Examples 1-12 and Comparative Examples 1-20 in the above process steps are shown in Tables 2-1 and 2-2.

Table 2-1

Number	Step 1	Step 2	Step 3					Whether performing normalizing annealing	Product thickness [mm]
	Slab thickness [mm]	Slab heating temperature [°C]	Rough rolling end temperature [°C]	Plate thickness after rough rolling [mm]	Coiling temperature [°C]	Coiling time [s]	Finishing rolling initial temperat ure [°C]
Example 1	190	1140	960	36	900	40	1040	Yes	0.30
Example 2	220	1090	980	48	1000	60	1000	Yes	0.27
Example 3	210	1150	970	44	980	80	980	Yes	0.23
Example 4	200	1130	1000	38	890	130	990	Yes	0.20
Example 5	240	1120	1100	42	820	160	1030	Yes	0.18
Example 6	250	1140	990	39	870	180	1015	Yes	0.27
Example 7	190	1020	1110	40	930	70	990	Yes	0.27
Example 8	200	1000	1000	49	950	90	995	Yes	0.27
Example 9	195	960	1000	48	1010	100	1000	Yes	0.27
Example 10	180	920	990	42	1040	150	1000	No	0.27
Example 11	235	940	980	45	1020	190	1010	No	0.27
Example 12	210	1000	1000	48	1015	120	1000	Yes	0.27
Comparative Example 1	220	1130	1000	40	1000	150	1000	Yes	0.27
Comparative Example 2	220	1130	1000	40	1000	150	1000	Yes	0.27
Comparative Example 3	200	1130	1020	45	1000	160	980	Yes	0.27
Comparative Example 4	220	1130	1000	45	1000	80	900	Yes	0.27
Comparative Example 5	220	1120	1010	40	1010	90	800	Yes	0.27
Comparative Example 6	210	1130	1030	38	980	100	890	Yes	0.27
Comparative Example 7	220	1100	1000	40	1000	120	1000	Yes	0.27
Comparative Example 8	230	1130	1000	40	900	120	1000	Yes	0.27
Comparative Example 9	230	1130	1000	40	900	120	1000	Yes	0.27
Comparative Example 10	230	1130	1000	40	900	120	1000	Yes	0.27
Comparative Example 11	200	1110	990	45	1000	110	1020	Yes	0.27
Comparative Example 12	220	1120	930	40	900	120	1000	Yes	0.27
Comparative Example 13	240	1110	1000	55	1000	130	1010	Yes	0.27
Comparative Example 14	230	1050	1000	45	1060	130	1020	Yes	0.27
Comparative Example 15	220	1090	1000	45	1010	210	1010	Yes	0.27
Comparative Example 16	190	1120	990	45	1010	180	1060	No	0.27
Comparative Example 17	240	1100	990	45	1020	160	1030	Yes	0.27
Comparative Example 18	200	1110	970	30	1010	28	1000	Yes	0.27
Comparative Example 19	220	1010	980	40	790	170	1020	Yes	0.27
Comparative Example 20	210	890	980	40	1000	180	1010	Yes	0.27

Table 2-2

Number	Normalizing annealing temperature	Normalizing annealing time	Step 4	Step 5	Step 6	Step 7	Step 8
			Cold rolling reduction ratio [%]	Decarburizing annealing temperature [°C]	Amount of nitriding [ppm]	Annealing separator	High-temperature annealing temperature [°C]	High-temperature annealing time [h]
Example 1	980	190	88	840	60	MgO	1110	30
Example 2	950	100	89	860	100	MgO	1140	36
Example 3	940	180	90	830	120	MgO	1250	28
Example 4	880	150	92	880	160	MgO	1220	29
Example 5	970	90	93	820	150	MgO	1200	38
Example 6	960	140	89	810	180	MgO	1180	34
Example 7	900	160	89	840	190	MgO	1150	31
Example 8	800	80	89	850	80	MgO	1100	26
Example 9	850	30	89	840	270	MgO	1150	30
Example 10	-	-	89	840	250	MgO	1150	30
Example 11	-	-	89	840	200	MgO	1150	30
Example 12	850	80	89	840	200	MgO	1150	30
Comparative Example 1	900	100	89	840	180	MgO	1200	30
Comparative Example 2	900	120	89	840	180	MgO	1200	30
Comparative Example 3	950	100	89	840	180	MgO	1200	30
Comparative Example 4	980	110	89	840	180	MgO	1200	30
Comparative Example 5	940	100	89	840	180	MgO	1200	30
Comparative Example 6	900	90	89	840	180	MgO	1200	30
Comparative Example 7	950	100	89	840	180	MgO	1200	30
Comparative Example 8	960	100	89	840	180	MgO	1200	30
Comparative Example 9	960	100	89	840	180	MgO	1200	30
Comparative Example 10	960	100	89	840	180	MgO	1200	30
Comparative Example 11	980	140	89	845	170	MgO	1200	30
Comparative Example 12	960	100	89	840	180	MgO	1200	30
Comparative Example 13	980	110	89	830	170	MgO	1200	30
Comparative Example 14	990	160	89	845	200	MgO	1200	30
Comparative Example 15	990	150	89	840	180	MgO	1200	30
Comparative Example 16	-	-	89	845	170	MgO	1200	30
Comparative Example 17	1010	150	89	840	170	MgO	1200	30
Comparative Example 18	950	210	89	840	220	MgO	1200	30
Comparative Example 19	950	15	89	910	290	MgO	1200	30
Comparative Example 20	960	150	89	780	40	MgO	1200	30

[0053] In step 5), the steel plates after decarburizing annealing of Examples 1-12 and Comparative Examples 1-20 were sampled, then the proportion of Gaussian grains with a deviation angle less than 3° of each sample was observed and analyzed by a scanning electron microscope with an electron backscatter diffraction (EBSD) system.

[0054] The proportion of Gaussian grains with a deviation angle less than 3° in the steel plates after decarburizing annealing of Examples 1-12 and Comparative Examples 1-20 are shown in Table 3.

Table 3

Number	Proportion of Gaussian grains with deviation angle less than 3° in steel plates after decarburizing annealing (%)
Example 1	12
Example 2	18
Example 3	21
Example 4	19
Example 5	17
Example 6	13
Example 7	14
Example 8	11
Example 9	22
Example 10	19
Example 11	20
Example 12	18
Comparative Example 1	8.2
Comparative Example 2	8.3
Comparative Example 3	8.4
Comparative Example 4	7.7
Comparative Example 5	6.1
Comparative Example 6	7.8
Comparative Example 7	6.4
Comparative Example 8	7.6
Comparative Example 9	6.8
Comparative Example 10	6.9
Comparative Example 11	8.9
Comparative Example 12	7.1
Comparative Example 13	7.9
Comparative Example 14	8.8
Comparative Example 15	9.2
Comparative Example 16	9.4
Comparative Example 17	3.6
Comparative Example 18	4.5
Comparative Example 19	4.8
Comparative Example 20	5.8

[0055] As shown in Table 3, the proportion of Gaussian grains with a deviation angle less than 3° in the steel plate after decarburizing annealing of Examples 1-12 is 11%-22%. In contrast, the proportion of Gaussian grains with a deviation angle less than 3° in the steel plate after decarburizing and annealing of Comparative Examples 1-20 is 3.6%-9.4%, which is significantly lower than those of Examples 1-12.

[0056] The oriented silicon steel products manufactured in Examples 1-12 and Comparative Examples 1-20 were sampled, and the magnetic properties of each sample were measured and analyzed to obtain the magnetic induction intensity B8 and the magnetostrictive vibration velocity sound pressure level L_vA of each oriented silicon steel sample.

[0057] In the present application, the related test methods for the magnetic properties of the oriented silicon steel are described below:
Magnetic property test: the magnetic induction intensity of the oriented silicon steel of Examples 1-12 and Comparative Examples 1-20 is determined in accordance with the national standard GB/T 13789-2008 "Method for Measuring the Magnetic Properties of Electrical Steel Sheets (Strips) with a Monolithic Tester".

[0058] Magnetostriction test: In accordance with IEC Technical Report IEC/TP 62581, the magnetostrictive vibration velocity sound pressure level L_vA of Examples 1-12 and Comparative Examples 1-20 is determined by a non-contact laser Doppler vibrometer at B=1.7 T and f=2 MPa (in the actual working conditions of the transformer, the compressive stress applied to the oriented silicon steel is 2-3 MPa). Herein, L_vA is the magnetostrictive vibration velocity sound pressure level of oriented silicon steel under the test conditions described above. The unit is dB(A)

[0059] The magnetic induction intensity B8 and the magnetostrictive vibration velocity sound pressure level L_vA of the oriented silicon steels of Examples 1-12 and Comparative Examples 1-20 are shown in Table 4.

Table 4

Number	B8 [T]	LvA [dB(A)]
Example 1	1.956	48
Example 2	1.962	46
Example 3	1.969	44
Example 4	1.958	45
Example 5	1.959	46
Example 6	1.956	47
Example 7	1.957	46
Example 8	1.954	48
Example 9	1.970	43
Example 10	1.967	45
Example 11	1.972	44
Example 12	1.965	45
Comparative Example 1	1.933	53
Comparative Example 2	1.912	58
Comparative Example 3	1.914	58
Comparative Example 4	1.891	60
Comparative Example 5	1.860	61
Comparative Example 6	1.908	58
Comparative Example 7	1.805	62
Comparative Example 8	1.899	58
Comparative Example 9	1.811	63
Comparative Example 10	1.899	60
Comparative Example 11	1.934	53
Comparative Example 12	1.913	55
Comparative Example 13	1.927	55
Comparative Example 14	1.932	55
Comparative Example 15	1.936	52
Comparative Example 16	1.939	51
Comparative Example 17	1.825	63
Comparative Example 18	1.804	64
Comparative Example 19	1.807	64
Comparative Example 20	1.819	63

[0060] As shown in Table 4, the magnetic induction intensity B8 of Examples 1-12 is 1.954-1.972 T, and the magnetostrictive vibration velocity sound pressure level L_vA is 43-48 dB(A). In contrast, the magnetic induction intensity B8 of Comparative Examples 1-20 is 1.805-1.939 T (apparently lower than Examples 1-12), and the magnetostrictive vibration velocity sound pressure level L_vA is 51-64 dB(A) (apparently higher than Examples 1-12).

[0061] As can be seen from Tables 1-4, the proportion of Gaussian grains with a deviation angle less than 3° in the steel plates after decarburizing annealing of Examples 1-12 is significantly higher than that of Comparative Examples 1-20, and their magnetic properties (in particular, the magnetic induction intensity B8 and L_vA) are significantly better than those of Comparative Examples 1-20.

[0062] After analyzing the proportion of Gaussian grains with a deviation angle less than 3° in the steel plate after decarburizing annealing, the present inventors surprisingly found that different combinations of hot rolling and normalizing annealing process parameters have a key influence on the deviation angle α of the Gaussian grain orientation in the steel plate after decarburizing annealing. The proportion of Gaussian grains with a deviation angle less than 3° in the steel plate after decarburizing annealing can be significantly increased, especially within the range of the chemical composition claimed in the present invention, by coiling and holding the rough-rolled plate at a temperature of 800-1050°C while subsequent low-temperature normalizing annealing (normalizing annealing temperatures of no more than 1000°C) is performed, or even no normalizing annealing treatment is performed. The present inventors have found through extensive experiments that the orientation degree of the Gaussian grain nuclei in the primary recrystallization has a decisive influence on the Gaussian grain orientation degree and the magnetic induction intensity of the product. As a result, the oriented silicon steel manufactured according to the method of the present invention shows a high level of matching between high magnetic induction intensity and low magnetostriction.

[0063] It should be noted that all the technical features recorded in this application may be freely combined or incorporated in any manner, unless they contradict each other. Various amendments and variations may be made to the present invention without departing from the scope of the invention, as will be apparent to those skilled in the art. For example, features shown or described as part of one embodiment may be used in conjunction with another embodiment to produce yet another embodiment. Accordingly, the present invention is intended to cover such amendments and variations as fall within the scope of the attached claims and their equivalents.

Claims

1. An oriented silicon steel, comprising, in addition to 90% or more of Fe and inevitable impurities, the following components in percentage by mass:
C: 0.020-0.080%, Si: 2.00-4.50%, Mn: 0.01-0.10%, S≤0.005%, acid soluble aluminum Als: 0.010-0.040%, N: 0.002-0.015%, Nb: 0.006-0.120%, and at least one selected from P: 0.01-0.10%, Sn: 0.01-0.30%, and Cu: 0.01-0.50%.

2. The oriented silicon steel as claimed in claim 1, characterized in that, the oriented silicon steel comprises the following components in percentage by mass:
C: 0.020-0.080%, Si: 2.00-4.50%, Mn: 0.01-0.10%, S≤0.005%, acid soluble aluminum Als: 0.010-0.040%, N: 0.002-0.015%, Nb: 0.006-0.120%, and at least one selected from P: 0.01-0.10%, Sn: 0.01-0.30%, and Cu: 0.01-0.50%; the balance of Fe and inevitable impurities.

3. The oriented silicon steel as claimed in claim 1 or 2, characterized in that, the oriented silicon steel has a thickness of 0.15-0.30 mm; preferably, the oriented silicon steel has a magnetic induction intensity of B8>1.95 T and a magnetostrictive vibration velocity sound pressure level of L_vA <50 dB(A).

4. A method for manufacturing the oriented silicon steel as claimed in any one of claims 1-3, comprising the following steps:

1) Smelting and casting a molten steel to produce a slab;

2) Heating the slab;

3) Hot rolling, including roughing rolling, coiling and holding, and finishing rolling;

4) Cold rolling;

5) Decarburizing annealing;

6) Nitriding;

7) Applying an annealing separator;

8) High-temperature annealing;

9) Applying an insulation coating and performing scoring to produce an oriented silicon steel.

5. The method as claimed in claim 4, characterized in that, in step 3), an end temperature of rough rolling is higher than 950°C, a coiling temperature is 800-1050°C, a coiling time is 30-200s, and an initial temperature of finishing rolling is lower than 1050°C.

6. The method as claimed in claim 4, characterized in that, after step 3) and before step 4), a normalizing annealing treatment is carried out, and the normalizing annealing temperature does not exceed 1000°C, preferably 800-1000°C, more preferably 800-980°C, and a normalizing annealing time is 20-200s.

7. The method as claimed in any one of claims 4-6, characterized in that, in step 2), a heating temperature of the slab is 900-1150°C.

8. The method as claimed in any one of claims 4-6, characterized in that, the method satisfies one or more of the following:

in step 1), a thickness of the slab is 180-250 mm;

in step 3), a thickness of the intermediate slab at the end of rough rolling is 35-50 mm;

in step 4), a cold rolling reduction ratio is >80%; and

in step 7), the annealing separator is MgO.

9. The method as claimed in any one of claims 4-6, characterized in that, in step 5), a decarburizing annealing temperature is 800-900°C; preferably, a proportion of Gaussian grains with a deviation angle less than 3° in the steel plate after decarburizing annealing is more than 10%.

10. The method as claimed in any one of claims 4-6, characterized in that, in step 6), an amount of nitriding is 50-280 ppm.

11. The method as claimed in any one of claims 4-6, characterized in that, in step 8), an annealing temperature is 1100-1250°C and an annealing time is greater than 25 hours.