Non-oriented silicon steel, high temperature ramp rate annealing process therefor, and manufacturing method therefor

Abstract

A high temperature ramp rate annealing process for a non-oriented silicon steel, comprising the following steps: (1) placing a silicon steel in a protective atmosphere, heating the silicon steel to a high temperature ramp rate inflection point at a heating rate of 70-200°C / s, and then heating the silicon steel to an annealing temperature at a heating rate of 10-30°C / s; (2) maintaining the temperature in the protective atmosphere; and (3) cooling the temperature-maintained non-oriented silicon steel.

Description

A non-oriented silicon steel and its high temperature variation rate annealing process and preparation method Technical Field

[0001] The present invention belongs to the technical field of metal materials, and in particular relates to a non-oriented silicon steel and a high temperature variation rate annealing process and a preparation method thereof. Background Art

[0002] Electricity is an indispensable energy source in modern society, the most common and important. The production, transmission, and use of electrical energy are inseparable from generators, transmission transformers, motors, and various electrical equipment and components such as ballasts, amplifiers, voltage regulators, relays, and rectifiers. Electromagnetic principles enable the conversion of mechanical energy into electrical energy, voltage into current, and the driving of electromechanical devices. A key component of these devices is the electromagnet core, the raw material of which is electrical steel, a cornerstone of the power and electrical industry.

[0003] Silicon steel is the most widely used soft magnetic material in industry, and industrial non-oriented silicon steel is the most widely used electrical steel, widely used in various motors. The performance of non-oriented silicon steel sheets not only directly affects power loss but also determines the performance, size, weight, and cost of products such as motors and transformers. Therefore, reducing iron loss and magnetic anisotropy and improving magnetic induction have become key research areas for silicon steel.

[0004] Summary of the Invention

[0005] The purpose of the present invention is to provide a non-oriented silicon steel with excellent magnetic properties and a manufacturing process thereof.

[0006] To this end, the present invention provides a high temperature variation rate annealing process for non-oriented silicon steel, comprising the following steps:

[0007] (1) placing the silicon steel in a protective atmosphere, heating it to a high temperature change rate turning point at a heating rate of 70-200°C / s, and then heating it to an annealing temperature at a heating rate of 10-30°C / s;

[0008] (2) Keep warm under a protective atmosphere;

[0009] (3) Cooling the non-oriented silicon steel after the insulation treatment.

[0010] Specifically, the high temperature ramp rate turning point X is 720-930°C; and the annealing temperature is 900-1100°C.

[0011] Specifically, the silicon steel includes the following components: C: 0-0.003%, Si: 1.0-4.5%, Al: 0.022-1.0%, Mn: 0.12-0.93%, N: 0-0.003%, S: 0-0.003%, P: 0-0.005%, and the rest is Fe and unavoidable impurities.

[0012] Specifically, the protective atmosphere is a nitrogen-hydrogen mixed atmosphere with an oxygen content of ≤0.5%.

[0013] Specifically, the holding temperature is 950-1050° C., and the holding time is 10-40 seconds.

[0014] Specifically, during the cooling process, the cooling rate between the holding temperature and the high temperature variation rate turning point is 15°C / s, and the cooling rate between the high temperature variation rate turning point and 30°C is 30°C / s.

[0015] Specifically, the dew point temperature during the annealing process is ≤-60°C.

[0016] Specifically, in the above step (1), before heating the silicon steel, the surface of the silicon steel is further cleaned for the first time using a first organic solvent, then cleaned for the second time using deionized water, and finally cleaned for the third time using a second organic solvent; the first organic solvent includes acetone, and the second organic solvent includes anhydrous ethanol.

[0017] The present invention also provides a method for preparing non-oriented silicon steel, comprising the following steps: smelting molten steel according to a set composition, casting the molten steel into a billet, hot rolling, normalizing pickling, and cold rolling the billet, and then annealing using any of the above-mentioned annealing processes to obtain non-oriented silicon steel.

[0018] The methods for smelting molten steel include smelting methods such as electric furnace and converter, the methods for forming molten steel into billets include continuous casting and rolling, ESP, CSP and thin strip continuous casting, and the cold rolling includes continuous rolling and single-stand reversible rolling.

[0019] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0020] The high temperature variation rate annealing process for non-oriented silicon steel provided by the present invention heats the silicon steel at a high temperature variation rate, thereby achieving complete recrystallization while obtaining relevant favorable textures and reducing harmful gamma-ray textures in the silicon steel, thereby significantly improving the magnetic properties of the non-oriented silicon steel, thereby producing high-performance non-oriented silicon steel with superior iron loss and magnetic induction to ordinary non-oriented silicon steel, thereby better meeting the application requirements of new energy motors.

[0021] The present invention will be described in further detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a comparison of RD magnetic properties at different temperature points; (a) iron loss, (b) magnetic induction.

[0023] Figure 2 is a comparison of TD magnetic properties at different temperature points; (a) iron loss, (b) magnetic induction.

[0024] FIG3 is a metallographic microstructure photograph of each silicon steel; (a) Comparative Example 1; (b) Comparative Example 2; (c) Comparative Example 3; (d) Example 1.

[0025] FIG4 is an IPF-Z diagram and a typical texture distribution diagram: (a, b) Comparative Example 1; (c, d) Comparative Example 2; (e, f) Comparative Example 3; (g, h) Example 1.

[0026] Figure 5 is an ODF diagram of φ2=45°: (a) Comparative Example 1; (b) Comparative Example 2; (c) Comparative Example 3; (d) Example 1. DETAILED DESCRIPTION

[0027] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Although the representative embodiments of the present invention have been described in detail, it will be understood by those skilled in the art that various modifications and changes can be made to the present invention without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the embodiments, but should be defined by the appended claims and their equivalents.

[0028] The present invention provides a high temperature variation rate annealing process for non-oriented silicon steel, comprising the following steps:

[0029] (1) Silicon steel contains the following components: C: 0-0.003%, Si: 1.0-4.5%, Al: 0.022-1.0%, Mn: 0.12-0.93%, N: 0-0.003%, S: 0-0.003%, P: 0-0.005%, and the remainder is Fe and unavoidable impurities. Silicon steel thickness ranges from 0.10mm to 0.65mm.

[0030] The target silicon steel surface is cleaned for the first time using a first organic solvent, then cleaned for the second time using deionized water, and finally cleaned for the third time using a second organic solvent; the first organic solvent includes acetone, and the second organic solvent includes anhydrous ethanol.

[0031] The cleaned silicon steel is placed in a furnace and heated in a protective atmosphere using gas, electric, radiant tube, or induction heating at a heating rate of 70-200°C / s to the high-temperature-rate turning point, then heated at a heating rate of 10-30°C / s to the annealing temperature. The high-temperature-rate turning point X is 720-930°C; the annealing temperature is 900-1100°C.

[0032] The protective atmosphere is preferably a nitrogen-hydrogen mixed atmosphere, with a nitrogen content of 0-100%, a hydrogen content of 0-100%, and an oxygen content of ≤0.05%.

[0033] (2) Keep warm under a protective atmosphere; the holding temperature is 950-1050°C and the holding time is 10-40s.

[0034] The protective atmosphere is preferably a nitrogen-hydrogen mixed atmosphere, with a nitrogen content of 0-100%, a hydrogen content of 0-100%, and an oxygen content of ≤0.05%.

[0035] (3) The non-oriented silicon steel after the insulation treatment is cooled by gas cooling or other methods, and the gas cooling includes at least one of nitrogen and hydrogen.

[0036] During the cooling process, the cooling rate from the holding temperature to the high temperature variation rate turning point X is 15°C / s, and the cooling rate from the high temperature variation rate turning point to 30°C is 30°C / s.

[0037] The dew point temperature during the annealing process is ≤-60℃.

[0038] The present invention also provides a method for preparing non-oriented silicon steel, comprising the following steps: smelting molten steel according to a set composition, casting the molten steel into a billet, hot rolling, normalizing pickling, and cold rolling the billet, and then annealing using any of the above-mentioned annealing processes to obtain non-oriented silicon steel.

[0039] The methods for smelting molten steel include electric furnace and converter smelting methods, the methods for forming molten steel into billets include continuous casting and rolling, ESP, CSP and thin strip continuous casting methods, and the cold rolling includes continuous rolling and single-stand reversible rolling.

[0040] The effects of the non-oriented silicon steel and the high temperature variation rate annealing process and preparation method thereof of the present invention are studied below through specific examples.

[0041] Example 1:

[0042] This embodiment provides a high-performance non-oriented silicon steel, which is prepared by the following steps.

[0043] S1. Molten steel is smelted according to the set composition and cast into ingots.

[0044] S2. hot rolling the ingot and coiling it.

[0045] S3. Cold rolling the hot coil to obtain target silicon steel with a thickness of 0.35 mm.

[0046] The target silicon steel includes the following components in mass percentage: C: 0.003%; Si: 2.9%; Al: 0.75%; Mn: 0.15%; N: 0.0025%; S: 0.0015%; P: 0.002%, and the rest is Fe and unavoidable impurities.

[0047] S4. In an air environment, first use acetone to clean the target silicon steel surface, then rinse its surface with deionized water, and finally clean it with anhydrous ethanol. Use a hair dryer to dry the silicon steel to remove oil and other stains on the silicon steel surface.

[0048] S5. Place the cleaned silicon steel in a furnace, wherein the oxygen content in the furnace is 0.02% and the nitrogen content is 99.98%.

[0049] The steel was heated from 30°C to 800°C at a heating rate of 100°C / s, and then heated to 980°C at a heating rate of 20°C / s to allow the silicon steel grains to recover and recrystallize.

[0050] The dew point temperature is -60℃.

[0051] S6. Keep the temperature at 980℃ for 30s to allow the grains to completely recrystallize and grow.

[0052] The oxygen content in the furnace is 0.02%, the nitrogen content is 99.98%, and the dew point temperature is -60℃.

[0053] S7. Cool the non-oriented silicon steel after the heat preservation treatment to complete the structural transformation.

[0054] During the cooling process, the cooling rate between 980°C and 800°C is 15°C / s, and the cooling rate between 650°C and 30°C is 30°C / s.

[0055] The oxygen content in the furnace is 0.02%, the nitrogen content is 99.98%, and the dew point temperature is -60℃.

[0056] Comparative Example 1:

[0057] The comparative example of the present invention provides a silicon steel, which adopts a preparation method similar to that of Example 1, except that the turning point of the high temperature variation rate in step S5 is at 700°C, the heating rate from 30-700°C is 30°C / s, and the heating rate from 700-980°C is 20°C / s.

[0058] Comparative Example 2:

[0059] The comparative example of the present invention provides a silicon steel, and the preparation method adopted is similar to that of Example 1, except that in step S5, the heating rate from 30-800℃ is 30℃ / s, and from 800-980℃ is 20℃ / s, and the turning point of the high temperature change rate is 800℃.

[0060] Comparative Example 3:

[0061] The comparative example of the present invention provides a silicon steel, which adopts a preparation method similar to that of Example 1, except that in step S5, the heating rate from 30-700℃ is 100℃ / s, and from 700-980℃ is 20℃ / s, and the turning point of the high temperature change rate is 700℃.

[0062] Example 2:

[0063] This example tests the properties of the silicon steel provided in Example 1 and Comparative Examples 1-3. The RD and TD magnetic properties are shown in Figures 1-2; the metallographic microstructure is shown in Figure 3; the IPF diagram and texture distribution diagram are shown in Figure 4; and the ODF diagram is shown in Figure 5. As can be seen from Figures 1-5, the high temperature ramp rate annealing process for non-oriented silicon steel provided by the present invention, by subjecting the silicon steel to a high temperature ramp rate heating treatment, allows the silicon steel to achieve complete recrystallization while simultaneously obtaining relevant favorable textures and reducing harmful gamma-ray textures, thereby significantly improving the magnetic properties of the non-oriented silicon steel. This results in the production of high-performance non-oriented silicon steel with superior iron loss and magnetic induction to conventional non-oriented silicon steel, better meeting the application requirements of new energy motors.

[0064] The above examples are merely illustrative of the present invention and do not limit the scope of protection of the present invention. Any design that is identical or similar to the present invention falls within the scope of protection of the present invention.

Claims

1. A high temperature variation rate annealing process for non-oriented silicon steel, characterized in that: The following steps are involved: (1) placing the silicon steel in a protective atmosphere, heating it to a high temperature change rate turning point at a heating rate of 70-200°C / s, and then heating it to an annealing temperature at a heating rate of 10-30°C / s; (2) Keep warm under a protective atmosphere; (3) Cooling the non-oriented silicon steel after the insulation treatment.

2. The high temperature variable rate annealing process for non-oriented silicon steel according to claim 1, wherein: The high temperature variation rate turning point is 720-930°C; the annealing temperature is 900-1100°C.

3. The high temperature variable rate annealing process for non-oriented silicon steel according to claim 1, wherein: The silicon steel comprises the following components in percentage by mass: C: 0-0.003%, Si: 1.0-4.5%, Al: 0.022-1.0%, Mn: 0.12-0.93%, N: 0-0.003%, S: 0-0.003%, P: 0-0.005%, and the rest is Fe and unavoidable impurities.

4. The high temperature variable rate annealing process for non-oriented silicon steel according to claim 1, wherein: The protective atmosphere is a nitrogen-hydrogen mixed atmosphere with an oxygen content of ≤0.05%.

5. The high temperature variable rate annealing process for non-oriented silicon steel according to claim 1, wherein: The holding temperature is 950-1050° C., and the holding time is 10-40 seconds.

6. The high temperature variable rate annealing process for non-oriented silicon steel according to claim 1, wherein: During the cooling process, the cooling rate between the holding temperature and the high temperature change rate turning point is 15°C / s, and the cooling rate between the high temperature change rate turning point and 30°C is 30°C / s.

7. The high temperature variable rate annealing process for non-oriented silicon steel according to claim 1, wherein: The dew point temperature during the annealing process is ≤-60°C.

8. The high temperature variable rate annealing process for non-oriented silicon steel according to claim 1, wherein: In the step (1), before heating the silicon steel, the surface of the silicon steel is first cleaned with a first organic solvent, then cleaned with deionized water for a second time, and finally cleaned for a third time with a second organic solvent; the first organic solvent includes acetone, and the second organic solvent includes anhydrous ethanol.

9. A method for preparing non-oriented silicon steel, characterized in that: The following steps are involved: Molten steel is smelted according to a set composition, cast into ingots, hot-rolled, normalized and pickled, and cold-rolled, and then annealed using the annealing process according to any one of claims 1 to 8 to obtain non-oriented silicon steel.

10. A non-oriented silicon steel, characterized in that: The non-oriented silicon steel is prepared by the preparation method according to claim 9.

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