Ultrahigh magnetic induction oriented silicon steel strip and preparation method thereof

Abstract

The invention provides an ultrahigh magnetic induction oriented silicon steel strip and a preparation method thereof, and the ultrahigh magnetic induction oriented silicon steel strip comprises the following chemical elements in percentage by mass: 0.04%-0.055% of C, 0.01%-0.015% of S, 0.005%-0.009% of N, 0.01%-0.02% of Ni, 0.01%-0.02% of Co, less than or equal to 1.605% of non-ferromagnetic elements Si, Mn and Al, and the balance of Fe and inevitable impurity elements. The magnetic performance is improved by adding ferromagnetic elements Ni and Co and inhibiting the total content of non-ferromagnetic elements Si, Mn and Al. Wherein the added Ni and Co elements are beneficial to refinement of the grain structure of a hot-rolled plate, are also beneficial to stable operation of secondary recrystallization, and inhibit growth of secondary grains with large orientation deviation, so that the magnetic induction performance of the silicon steel strip is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of the rolling of grain-oriented silicon steel strip, and particularly relates to a high ultra-high magnetic induction grain-oriented silicon steel strip and a preparation method thereof. Background Art

[0002] Flexible low-frequency AC power transmission technology is a new technology for future applications such as long-distance wide-area networking power transmission, onshore large-scale new energy collection and transmission, medium- and long-distance offshore wind power transmission, and flexible interconnection of urban power grid partitions. In technology research and development and demonstration projects, it is found that the core equipment, the low-frequency transformer, has problems such as large volume, heavy weight, and high load loss, which become one of the important factors affecting the technical economy of the flexible low-frequency AC power transmission system. To avoid low-frequency saturation of the transformer, the volume, weight, and load loss of the low-frequency transformer used in flexible low-frequency power transmission are all greater than those of the power-frequency AC, which will affect the project cost. Under the conditions of the same voltage level and capacity, when the frequency is reduced from 50 Hz to 20 Hz, compared with the power-frequency transformer, the weight of the 220 kV low-frequency transformer increases by 70%, the floor area increases by 21%, the volume increases by 34%, and the load loss of the transformer increases by 33%. Therefore, reducing weight, volume, and load loss is an urgent problem to be solved in the development of low-frequency transformer technology, and the magnetic properties of the grain-oriented silicon steel used as the core material are the most core factors restricting weight, volume, and load loss.

[0003] However, a relatively large deviation angle of Gaussian grain orientation and a relatively low content in the grain-oriented silicon steel material tend to deteriorate the magnetic properties of the grain-oriented silicon steel and reduce its magnetic induction value B 800 . The existing magnetic induction value B of the grain-oriented silicon steel 800 The limit value is about 1.95 T, which cannot meet the technical development requirements of the volume, weight, and load loss of the low-frequency transformer.

[0004] Therefore, it is necessary to provide a new ultra-high magnetic induction grain-oriented silicon steel strip and a preparation method thereof. Summary of the Invention

[0005] The purpose of the present invention is to solve the technical problem of the poor magnetic induction performance of the existing silicon steel strip.

[0006] The purpose of the present invention is achieved by adopting the following technical solutions: The present invention provides an ultra-high magnetic induction grain-oriented silicon steel strip, which, by mass percentage, comprises the following chemical elements: C: 0.04% - 0.055%, S: 0.01% - 0.015%, N: 0.005% - 0.009%, Ni: 0.01% - 0.02%, Co: 0.01% - 0.02%, the sum of the contents of the non-ferromagnetic elements Si, Mn, and Al ≤ 1.605%, and the balance is Fe and inevitable impurity elements.

[0007] Preferably, in the non-ferromagnetic elements, Si is 0.3% - 1.5%, Mn is 0.01% - 0.08%, and Al is 0.015% - 0.025%.

[0008] Preferably, the chemical elements include: C: 0.055%, Si: 0.3%, Mn: 0.08%, S: 0.015%, Al: 0.025%, N: 0.009%, Ni: 0.02%, Co: 0.010%, and the balance is Fe and inevitable impurity elements.

[0009] Based on the same inventive concept, the present invention also provides a method for preparing the ultra-high magnetic induction oriented silicon steel strip, comprising the following steps: hot rolling process, normalizing process, cold rolling process, decarburizing annealing process, and high-temperature annealing process.

[0010] Preferably, the starting rolling temperature in the hot rolling process is 1180°C - 1300°C, and the final rolling temperature is 950°C - 1050°C.

[0011] Preferably, the total rolling force in the hot rolling process is 10T - 30T, and the thickness of the strip after hot rolling is 2.0mm - 2.3mm.

[0012] Preferably, the normalizing temperature in the normalizing process is 1000°C - 1050°C, the normalizing time is 2min - 5min, the atmosphere is N2, and the gas flow rate is 1 - 10L / min.

[0013] Preferably, the atmosphere in the normalizing process is N2, and the gas flow rate is 1L / min - 10L / min.

[0014] Preferably, the rolling rate in the cold rolling process is 150m / min - 250m / min, and the number of rolling passes is 4 - 8 times.

[0015] Preferably, the thickness of the strip after cold rolling in the cold rolling process is 0.25mm - 0.35mm.

[0016] Preferably, the annealing temperature in the decarburizing annealing process is 850°C - 880°C, the annealing time is 3min - 5min, and the annealing atmosphere is wet nitrogen-hydrogen mixed gas.

[0017] Preferably, in the nitrogen-hydrogen mixed gas in the decarburizing annealing process, the ratio is 1:3 - 1:1, the gas flow rate is 4L / min - 8L / min, and the dew point temperature is 15°C - 30°C.

[0018] Preferably, the annealing temperature in the high-temperature annealing process is 1100°C - 1200°C, and the annealing duration is 10h - 40h.

[0019] Preferably, the annealing atmosphere in the high-temperature annealing process is a nitrogen-hydrogen mixture, with the nitrogen ratio being 50%-75% and the gas flow rate being 2L / min-5L / min.

[0020] Preferably, the magnetic induction value B of the strip obtained after the high-temperature annealing 800 ≥1.98T.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention provides an ultra-high magnetic induction oriented silicon steel strip and a preparation method. By mass percentage, it includes the following chemical elements: C: 0.04%-0.055%, S: 0.01%-0.015%, N: 0.005%-0.009%, Ni: 0.01%-0.02%, Co: 0.01%-0.02%. The sum of the contents of non-ferromagnetic elements Si, Mn, and Al is ≤1.605%, and the balance is Fe and inevitable impurity elements. In the silicon steel strip of the present invention, the magnetic induction performance is enhanced by adding ferromagnetic elements Ni and Co and suppressing the total content of non-ferromagnetic elements Si, Mn, and Al. Among them, the added Ni and Co elements are beneficial to refining the grain structure of the hot-rolled sheet, and also beneficial to the stable progress of secondary recrystallization, suppressing the growth of secondary grains with large orientation deviation angles, and thus improving the magnetic induction performance of the strip.

[0022] In the preparation method of the present invention, the hot-rolling temperature is controlled within the range of 1180°C-1300°C, avoiding the disadvantages of high energy consumption cost, short furnace life, many product surface defects, and large burning loss caused by the conventional high-temperature hot-rolling technology of ≥1350°C. It also avoids the problem of low Goss texture content and too large orientation deviation angle due to excessive rolling shear resistance during the low-temperature hot-rolling process of 1150°C-1200°C. This preparation method is simple in operation and high in production efficiency. Compared with the silicon steel strip prepared by the existing process, the silicon steel strip prepared by the present invention has better magnetic induction performance, and its magnetic induction value B 800 ≥1.98T, meeting the application requirements of electrical equipment such as low-frequency transformers. Description of the Drawings

[0023] Figure 1 is the electron microscope magnification diagram of the structure before hot rolling of the ultra-high magnetic induction oriented silicon steel strip in Example 2 of the present invention; Figure 2 is the electron microscope magnification diagram of the structure after hot rolling of the ultra-high magnetic induction oriented silicon steel strip in Example 2 of the present invention; Figure 3 is the electron microscope magnification diagram of the secondary recrystallization structure of the ultra-high magnetic induction oriented silicon steel strip in Example 1 of the present invention; Figure 4 is the electron microscope magnification diagram of the secondary recrystallization structure of the ultra-high magnetic induction oriented silicon steel strip in Example 2 of the present invention; Figure 5It is the electron microscope magnification view of the secondary recrystallization structure of the ultra-high magnetic induction oriented silicon steel strip in Embodiment 3 of the present invention; Figure 6 It is the electron microscope magnification view of the secondary recrystallization structure of the ultra-high magnetic induction oriented silicon steel strip in Embodiment 4 of the present invention. Specific embodiments

[0024] The following embodiments are provided to better further understand the present invention, which is not limited to the best embodiment, and does not limit the content and protection scope of the present invention. Any product that is the same as or similar to the present invention obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with other prior art features falls within the protection scope of the present invention.

[0025] For those steps or conditions of specific experiments not specified in the present invention, the operations or conditions of the conventional experimental steps described in the literature in this field can be followed.

[0026] The present invention provides an ultra-high magnetic induction oriented silicon steel strip, which includes the following chemical elements by mass percentage: C: 0.04% - 0.055%, S: 0.01% - 0.015%, N: 0.005% - 0.009%, Ni: 0.01% - 0.02%, Co: 0.01% - 0.02%, the sum of the contents of non-ferromagnetic elements Si, Mn, and Al ≤ 1.605%, and the balance is Fe and inevitable impurity elements.

[0027] Specifically, among the non-ferromagnetic elements, Si: 0.3% - 1.5%, Mn: 0.01% - 0.08%, Al: 0.015% - 0.025%.

[0028] Among them, the preparation method of the ultra-high magnetic induction oriented silicon steel strip of the present invention includes: S1 hot rolling process, S2 normalizing process, S3 cold rolling process, S4 decarburizing annealing process, and S5 high-temperature annealing process.

[0029] In the step S1 hot rolling process, the starting rolling temperature is 1180°C - 1300°C, the final rolling temperature is 950°C - 1050°C, the total rolling force is 10T - 30T, and the thickness of the strip after hot rolling is 2.0mm - 2.3mm.

[0030] In the step S2 normalizing process, the normalizing temperature is 1000°C - 1050°C, the normalizing time is 2min - 5min, the atmosphere is N2, and the gas flow rate is 1L / min1 - 10L / min.

[0031] In the step S3 cold rolling process, the rolling rate in the cold rolling process is 150m / min - 250m / min, the number of rolling passes is 4 - 8 times, and the thickness of the strip after cold rolling in the cold rolling process is 0.25mm - 0.35mm.

[0032] In the decarburization annealing process of step S4, the annealing temperature is 850°C - 880°C, the annealing time is 3 min - 5 min, the annealing atmosphere is a wet nitrogen-hydrogen mixture, the ratio in the nitrogen-hydrogen mixture is 1:3 - 1:1, the gas flow rate is 4 L / min - 8 L / min, and the dew point temperature is 15°C - 30°C.

[0033] In the high-temperature annealing process of step S5, the annealing temperature is 1100°C - 1200°C, the annealing duration is 10 h - 40 h, the annealing atmosphere is a nitrogen mixture, the nitrogen ratio is 50% - 75%, and the gas flow rate is 2 L / min - 5 L / min.

[0034] The chemical element ratios and preparation process parameters of the ultra-high magnetic induction oriented silicon steel strip in the above different ranges are selected to obtain the following specific embodiments.

[0035] Examples 1 - 4 Table 1 shows the comparison of the chemical element ratios and preparation process parameters of the ultra-high magnetic induction oriented silicon steel strips in Examples 1 - 4 as follows: Table 1

[0036] See the following table

[0037] Comparative Example 1 The difference in the chemical element content of the silicon steel strip in this Comparative Example 1 from that in Example 1 is that in this Comparative Example 1, the elements Ni: 0.002% and Co: 0.004%, and the content of both is ≤0.005%. The content of the added non-ferromagnetic elements is Si: 1.65%, Mn: 1.0%, Al: 0.030%, and the total content of the non-ferromagnetic elements is 2.68% (exceeding 1.6%).

[0038] The preparation method of the silicon steel strip in this Comparative Example 1 is exactly the same as the process parameters of the preparation method in Example 1, so it will not be elaborated here.

[0039] Comparative Example 2 The chemical element content of the silicon steel strip in this Comparative Example 2 is exactly the same as that in Example 2, so it will not be elaborated here.

[0040] The difference in the preparation method of the silicon steel strip in this Comparative Example 2 from that in Example 2 is that in the S1 hot rolling process, the starting rolling temperature is 1140°C and the final rolling temperature is 900°C, and the other preparation process parameters are exactly the same as the process parameters of the preparation method in Example 2, so it will not be elaborated here.

[0041] Comparative Example 3 The difference in the chemical element content of the silicon steel strip in Comparative Example 3 from that in Example 4 is that the nitrogen content in the chemical elements is 0.003%.

[0042] The process parameters of the preparation method of the silicon steel strip in Comparative Example 3 are exactly the same as those in Example 4, so they will not be elaborated here.

[0043] Result Test The magnetic induction B of the ultra-high magnetic induction grain-oriented silicon steel strip samples in Examples 1 to 4 and Comparative Examples 1 to 3 was respectively 800 The test results are shown in Table 2: Table 2

[0044] Table 2 is a comparison table of the magnetic induction values B of the ultra-high magnetic induction grain-oriented silicon steel strips in Examples 1 - 4 and Comparative Examples 1 - 3 800 comparison table.

[0045] It can be seen from the comparison that the magnetic induction value B of the ultra-high magnetic induction grain-oriented silicon steel strip prepared by the present invention 800 all exceeds 1.98. The magnetic induction performance of the ultra-high magnetic induction grain-oriented silicon steel strip in Example 2 is the best, and its value B 800 reaches 1.995 (the highest value).

[0046] Among them, when the Ni and Co contents in Comparative Example 1 are less than the set range values of the present invention, Ni: 0.01% - 0.02%, Co: 0.01% - 0.02%, the magnetic induction value of the grain-oriented silicon steel in Comparative Example 1 significantly drops to 1.901.

[0047] When the starting rolling temperature in Comparative Example 2 is 1140°C and the final rolling temperature is 900°C, which are significantly lower than the starting rolling temperature of 1180°C - 1300°C and the final rolling temperature of 950°C - 1050°C in the preparation method of the present invention, the magnetic induction value of the grain-oriented silicon steel in Comparative Example 2 is affected after hot rolling treatment, and it significantly drops to 1.893 (the lowest value).

[0048] When the N content in Comparative Example 3 is less than the set range value of the present invention, N: 0.005% - 0.009%, the magnetic induction value of the grain-oriented silicon steel in Comparative Example 3 also significantly drops to 1.914.

[0049] As Figure 1 and Figure 2 shown, by comparing the grain refinement structures of the silicon steel strip before and after hot rolling in Example 2, it can be seen that the grain structure in the grain-oriented silicon steel material in this Example 2 is smaller.

[0050] As Figures 3 to 6As shown, they are respectively the metallographic diagrams of the secondary recrystallization structure of the materials of the ultra-high magnetic induction grain-oriented silicon steel strips in Examples 1-4 after high-temperature annealing. By comparison, it can be seen that the organizational structure distribution of the secondary recrystallization structure of the silicon steel strips is uniform.

[0051] In summary, by adopting the chemical element component range of the ultra-high magnetic induction grain-oriented silicon steel strips of the present invention and combining processes such as hot rolling, normalizing, cold rolling, decarburization annealing, and high-temperature annealing, and by controlling the content of chemical components in the silicon steel strips within a specific proportion range (such as the total content of Ni, Co, N, and non-ferromagnetic elements) in combination with the preparation method (such as hot rolling temperature control), etc., the magnetic induction value of the grain-oriented silicon steel can be significantly improved. This preparation method is simple to operate and has high production efficiency, meeting the requirements of high-efficiency production of enterprises.

[0052] The above are only examples of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention are included in the scope of the claims of the present invention pending approval.

Claims

1. An ultra-high magnetic induction oriented silicon steel strip, characterized in that, By mass percentage, it includes the following chemical elements: C: 0.04% - 0.055%, S: 0.01% - 0.015%, N: 0.005% - 0.009%, Ni: 0.01% - 0.02%, Co: 0.01% - 0.02%. The sum of the contents of non - ferromagnetic elements Si, Mn, and Al is ≤1.605%, and the balance is Fe and inevitable impurity elements.

2. The ultra-high magnetic induction oriented silicon steel strip according to claim 1, characterized in that, Among the non - ferromagnetic elements, Si: 0.3% - 1.5%, Mn: 0.01% - 0.08%, Al: 0.015% - 0.025%.

3. The ultra-high magnetic induction oriented silicon steel strip according to claim 2, characterized in that, The chemical elements include: C: 0.055%, Si: 0.3%, Mn: 0.08%, S: 0.015%, Al: 0.025%, N: 0.009%, Ni: 0.02%, Co: 0.010%, and the balance is Fe and inevitable impurity elements.

4. A method for preparing an ultra-high magnetic induction oriented silicon steel strip according to any one of claims 1-3, characterized in that, It includes the following steps: hot - rolling process, normalizing process, cold - rolling process, decarburizing annealing process, and high - temperature annealing process.

5. The preparation method of the ultra-high magnetic induction oriented silicon steel strip according to claim 4, characterized in that, The starting rolling temperature in the hot - rolling process is 1180°C - 1300°C, and the final rolling temperature is 950°C - 1050°C.

6. The preparation method of the ultra-high magnetic induction oriented silicon steel strip according to claim 5, characterized in that, The total rolling force in the hot - rolling process is 10T - 30T, and the thickness of the hot - rolled strip is 2.0mm - 2.3mm.

7. The preparation method of the ultra-high magnetic induction oriented silicon steel strip according to claim 4, characterized in that The normalizing temperature in the normalizing process is 1000°C - 1050°C, the normalizing time is 2min - 5min, the atmosphere is N2, and the gas flow rate is 1 - 10L / min.

8. The preparation method of the ultra-high magnetic induction oriented silicon steel strip according to claim 7, characterized in that, The atmosphere in the normalizing process is N2, and the gas flow rate is 1L / min - 10L / min.

9. The method for preparing an ultra-high magnetic induction oriented silicon steel strip according to claim 4, characterized in that, The rolling rate in the cold - rolling process is 150m / min - 250m / min, and the number of rolling passes is 4 - 8 times.

10. The preparation method of the ultra-high magnetic induction oriented silicon steel strip according to claim 9, characterized in that, The thickness of the cold - rolled strip after cold - rolling in the cold - rolling process is 0.25mm - 0.35mm.

11. The preparation method of the ultra-high magnetic induction oriented silicon steel strip according to claim 4, characterized in that, The annealing temperature in the decarburizing annealing process is 850°C - 880°C, the annealing time is 3min - 5min, and the annealing atmosphere is wet nitrogen - hydrogen mixed gas.

12. The method for preparing the ultra-high magnetic induction oriented silicon steel strip according to claim 11, characterized in that, In the nitrogen - hydrogen mixed gas in the decarburizing annealing process, the ratio is 1:3 - 1:1, the gas flow rate is 4L / min - 8L / min, and the dew - point temperature is 15°C - 30°C.

13. The preparation method of the ultra-high magnetic induction oriented silicon steel strip according to claim 4, characterized in that, The annealing temperature in the high - temperature annealing process is 1100°C - 1200°C, and the annealing duration is 10h - 40h.

14. The method for preparing the ultra-high magnetic induction oriented silicon steel strip according to claim 13, characterized in that, The annealing atmosphere in the high - temperature annealing process is nitrogen mixed gas, the nitrogen ratio is 50% - 75%, and the gas flow rate is 2L / min - 5L / min.

15. The preparation method of the ultra-high magnetic induction oriented silicon steel strip according to claim 4, characterized in that, The magnetic induction value B of the strip obtained after the high-temperature annealing 800 ≥ 1.98 T.

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