Efficient non-oriented electrical steel for industrial motor and preparation method

Abstract

The invention discloses high-efficiency non-oriented electrical steel for an industrial motor and a preparation method. The high-efficiency non-oriented electrical steel comprises the following chemical components in percentage by weight: not less than 0.0010% and not more than 0.0020% of C, not less than 2.2% and not more than 2.5% of Si, not less than 0.3% and not more than 0.7% of Mn, not less than 0.3% and not more than 0.6% of Als, not less than 0.0010% and not more than 0.0020% of Ti, not less than 0.0020% and not more than 0.0040% of C and Ti, and the balance of Fe and inevitable impurities. Precious metal elements and rare earth elements are not added, so that the production cost is greatly reduced; according to the produced non-oriented silicon steel, the magnetic performance P1.5 / 50 is equal to 2.09-2.21 W / kg, the magnetic performance B50 is equal to 1.70-1.72 T, the iron loss and magnetic induction ratio P1.5 / 50 / B50 is equal to 1.21-1.30, the lower the value is, the better the magnetic performance is, and therefore the iron loss and magnetic induction of the product are considered at the same time.

Description

Technical Field

[0001] The invention belongs to the technical field of full-process non-oriented silicon steel production and preparation, and specifically relates to a high-efficiency non-oriented electrical steel for industrial motors and a preparation method thereof. Background Art

[0002] The huge competitive pressure and challenges faced by the international community in my country's motor industry are increasing. From the perspective of international and domestic development trends, it is very necessary to promote China's high-efficiency motors. This is also a requirement for product development, so that my country's motor products can keep up with the international development trend, and it is also conducive to promoting the technological progress of the industry and the need for product exports. Under the influence of a series of market factors, the profit margins of most motor companies in my country have been further compressed. Against the background of high costs and further strengthening of environmental protection supervision, high-efficiency and energy-saving motors are the inevitable direction of the development of the motor industry. As an important component of industrial motors, the performance improvement method of high-efficiency non-oriented silicon steel for industrial motors is particularly important.

[0003] Iron loss and magnetic induction are two important performance indicators of non-oriented silicon steel, that is, the lower the iron loss and the higher the magnetic induction, the better the magnetic properties. However, the two cannot be taken into account at the same time. Therefore, reducing iron loss and improving magnetic induction is a key issue faced in the development of high-efficiency non-oriented silicon steel.

[0004] Chinese invention patent application CN 110777299 A discloses a method for preparing Ce-containing high magnetic induction non-oriented silicon steel. By adding rare earth element Ce to optimize the texture and grain size of the finished product, the magnetic induction of the finished product has been improved. The iron loss P 1.5 / 50 At 3.432W / kg, magnetic induction B 50 Around 1.78 T. The patent application adds rare earth elements, which can improve the magnetic induction of the finished product, but will bring extremely high production costs in industrial production, and it is difficult to apply it in large-scale industrial production.

[0005] Chinese invention patent CN 114214561 B discloses a non-oriented silicon steel strip for ultra-high efficiency variable frequency air conditioner compressor and its manufacturing method, which mainly adds segregation element Sn, cooperates with heat treatment processes such as continuous casting, hot rolling, normalizing and continuous annealing, and excellent cold rolling plate shape control technology to achieve a high-efficiency non-oriented silicon steel product with a thickness of 0.30-0.35mm and excellent magnetic properties. The Sn element added in this invention patent is costly, and the addition of Sn element will lead to a decrease in hot working performance and affect product quality. Summary of the invention

[0006] The purpose of the present invention is to provide a high-efficiency non-oriented electrical steel for industrial motors and a preparation method thereof, in view of the deficiencies in the prior art.

[0007] To achieve the above object, the present invention provides a high-efficiency non-oriented electrical steel for industrial motors, the chemical composition of which includes, by weight percentage: 0.0010%≤C≤0.0020%, 2.2%≤Si≤2.5%, 0.3%≤Mn≤0.7%, 0.3%≤Als≤0.6%, 0.0010%≤Ti≤0.0020%, 0.0020%≤C+Ti≤0.0040%, and the rest is Fe and unavoidable impurities.

[0008] Furthermore, the C is preferably 0.0017-0.0019%.

[0009] Furthermore, the Ti content is preferably 0.0017 to 0.0018%.

[0010] Furthermore, the C+Ti is preferably 0.0034-0.0036%.

[0011] A method for preparing the high-efficiency non-oriented electrical steel for industrial motors as described above is also provided as follows:

[0012] 1) Pre-treating the molten iron, smelting in a converter, and vacuum treating the slab according to the chemical composition described above, and then continuously casting the slab into a slab with a thickness of 200 to 300 mm;

[0013] 2) Hot rolling: the final rolling temperature of hot rolling is 830-880°C and rolled into a hot-rolled plate with a thickness of 2.2-2.6 mm. After air cooling and water cooling, the temperature is reduced to the coiling temperature of 650-680°C;

[0014] 3) Normalized pickling: heat the strip to 450-550℃ with an open flame for 30-45s, then rapidly heat to 920-950℃ at a rate of 15-20℃ / s and keep warm for 2-5min; the temperature of the pickling solution is 75-80℃;

[0015] 4) cold rolling on a reversible rolling mill with multiple passes to a target thickness of 0.35 mm;

[0016] 5) Finished product annealing, heating to 900-980°C at a heating rate of 40-50°C / s for 90-100s, with the hydrogen volume fraction in the furnace controlled at 5-10%; the dew point in the furnace controlled at ≤-10°C; after annealing, the insulating coating is applied by a coating roller and the insulating coating is cured;

[0017] Magnetic properties of the steel obtained 1.5 / 50 =2.09~2.21W / kg, B 50 =1.70~1.72T, iron loss magnetic induction ratio: P 1.5 / 50 / B 50 =1.21~1.30.

[0018] Furthermore, the hot rolling final rolling temperature is 860-880° C. to form a hot rolled plate with a thickness of 2.2-2.4 mm.

[0019] Furthermore, the coiling temperature is 650-660°C.

[0020] Furthermore, the open flame heating temperature is 480-500°C.

[0021] Furthermore, the heating rate of the finished product annealing is 45-50°C / s, and the temperature is heated to 950-980°C.

[0022] Furthermore, the insulating coating is cured at 440-570°C.

[0023] For the two important magnetic performance indicators of non-oriented silicon steel: iron loss and magnetic induction, there is a "seesaw" law between the two, and the two cannot be optimized at the same time. Non-oriented silicon steel contains many randomly oriented grains, and the easy magnetization directions of different grains are different. Improving the magnetic induction often requires optimizing the grain orientation, but this will make the magnetic domain structure more orderly, resulting in increased hysteresis loss, that is, increased iron loss; in addition, in non-oriented silicon steel, the addition of silicon can increase the resistivity of silicon steel, reduce eddy current loss, and thus reduce iron loss. However, excessive silicon content will inhibit the improvement of magnetic induction. When adding other alloying elements to improve the magnetic induction, the iron loss may increase due to changes in the crystal structure or the formation of new phases. Cold rolling can refine the grains, improve the texture, and improve the magnetic induction, but excessive rolling will cause stress and defects inside the material, increase the resistance to the movement of the magnetic domain wall, increase the hysteresis loss, and increase the iron loss; annealing can eliminate stress and improve the magnetic domain structure to reduce iron loss, but if the annealing temperature and time are not properly controlled, the grains will grow unevenly, affecting the magnetic induction. Therefore, it is difficult to achieve both high magnetic induction and low iron loss in the production process of conventional non-oriented silicon steel. Currently, the addition of rare earth elements and metal elements such as Sn can effectively improve the magnetic induction. Combined with high-temperature heat treatment technology, non-oriented silicon steel products with lower iron loss and higher magnetic induction can be obtained, but the cost is relatively high.

[0024] Normalization is an important process in the production of non-oriented silicon steel, which has a great influence on the performance. Rapid heating can optimize the texture components and form a {100} texture. However, too fast a heating rate will also cause thermal stress due to the large temperature difference between the surface and the middle, which will also lead to the refinement of the material grain size, which is not conducive to iron loss. A faster heating rate during continuous annealing can improve the texture of the finished product, which is beneficial to the magnetic properties, but will also lead to a smaller grain size, which is beneficial to medium and high frequency iron losses. However, for industrial motors, due to their operating conditions, medium and high frequency iron losses are generally not a concern.

[0025] Therefore, the present invention controls the amount of fine inclusions by controlling the content of impurity elements C and Ti, reduces the "pinning" of fine inclusions on the magnetic domain wall, and reduces the resistance to magnetic domain rotation and domain wall movement, thereby optimizing the electromagnetic properties; by controlling the normalizing and continuous annealing heating rates, the generation of unfavorable textures is suppressed, the proportion of favorable textures is increased, and the optimal texture and microscopic state are determined, so as to obtain a finished product control technology with "double excellence" in iron loss and magnetic induction.

[0026] Compared with the prior art, the invention has the following beneficial effects: the invention does not add precious metal elements and rare earth elements, thus greatly reducing the production cost; the produced non-oriented silicon steel has the following magnetic properties: 1.5 / 50 =2.09~2.21W / kg, B 50 =1.70~1.72T, iron loss magnetic induction ratio: P 1.5 / 50 / B 50 =1.21~1.30, the lower the value, the better the magnetic properties, therefore, the iron loss and magnetic induction of the product are taken into account at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is the normalized texture diagram of Comparative Example 1;

[0028] Figure 2 is the normalized texture diagram of Example 1;

[0029] Figure 3 This is the product texture diagram of Comparative Example 1;

[0030] Figure 4 This is the product texture diagram of Example 1. DETAILED DESCRIPTION

[0031] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0032] Example 1

[0033] The chemical composition by weight percentage is: C: 0.0019%, Si: 2.35%, Mn: 0.45%, Als: 0.55%, Ti: 0.0018%, C+Ti: 0.0037%, and the rest is Fe and unavoidable impurities;

[0034] The steel with the above chemical composition is subjected to molten iron pretreatment, converter steelmaking, vacuum treatment, and then continuously cast into a slab with a thickness of 200 to 300 mm;

[0035] After hot rolling, the final rolling temperature of hot rolling is 860℃, and the hot rolled plate is rolled into a 2.2mm thick hot rolled plate. After air cooling and water cooling, the temperature is reduced to the coiling temperature of 680℃.

[0036] Normalized pickling: the strip is heated to 500℃ by open flame, the heating time is controlled at 42s, and then rapidly heated to 950℃ at a speed of 16℃ / s, and the holding time is 4min; the pickling liquid temperature is 75~80℃;

[0037] Cold rolling was carried out on a reversing mill, with a target thickness of 0.35 mm in 6 passes;

[0038] Finally, the finished product is annealed. The heating section adopts a rapid heating method, heating to 980°C at a heating rate of 50°C / s for 90s. The hydrogen gas volume fraction in the furnace is controlled at 5-10%; the dew point in the furnace is controlled at ≤-10°C; after annealing, the insulating coating is applied by a coating roller and cured at 440-570°C.

[0039] The high-efficiency non-oriented electrical steel for industrial motors obtained by the above production method has a magnetic property P 1.5 / 50 =2.16W / kg, B 50 =1.72T, iron loss magnetic induction ratio: P 1.5 / 50 / B 50 =1.25.

[0040] Example 2

[0041] The chemical composition by weight percentage is: C: 0.0019%, Si: 2.38%, Mn: 0.48%, Als: 0.55%, Ti: 0.0018%, C+Ti: 0.0037%. The rest is Fe and unavoidable impurities;

[0042] The steel with the above chemical composition is subjected to molten iron pretreatment, converter steelmaking, vacuum treatment, and then continuously cast into a slab with a thickness of 200 to 300 mm;

[0043] The final rolling temperature of hot rolling is 880℃, and the hot rolled plate is rolled into 2.3mm thick hot rolled plate. After air cooling and water cooling, the temperature is reduced to 650℃ for coiling.

[0044] Normalized pickling: open flame heats the strip to 480℃, the heating time is controlled at 40s, then rapidly heats to 930℃ at a rate of 20℃ / s, and the holding time is 4min; the pickling solution temperature is 75~80℃;

[0045] Cold rolling was carried out on a reversing mill with 6 passes to a target thickness of 0.35 mm.

[0046] Finally, the finished product is annealed. The heating section adopts a rapid heating method and is heated to 980°C at a heating rate of 50°C / s for 100s. The hydrogen gas volume fraction in the furnace is controlled at 10%; the dew point in the furnace is controlled at ≤-10°C; after annealing, the insulating coating is applied by a coating roller and cured at 440-570°C.

[0047] By adopting the above production method, a high-efficiency non-oriented electrical steel for industrial motors can be obtained. The magnetic properties of the finished product are P 1.5 / 50 =2.09W / kg, B 50 =1.71T, iron loss magnetic induction ratio: P 1.5 / 50 / B 50 =1.22.

[0048] Example 3

[0049] The chemical composition by weight percentage is: C: 0.0017%, Si: 2.45%, Mn: 0.48%, Als: 0.53%, Ti: 0.0017%, C+Ti: 0.0034%. The rest is Fe and unavoidable impurities;

[0050] The steel with the above chemical composition is subjected to molten iron pretreatment, converter steelmaking, vacuum treatment, and then continuously cast into a slab with a thickness of 200 to 300 mm;

[0051] The final rolling temperature of hot rolling is 880℃, and the hot rolled plate is rolled into a 2.2mm thick hot rolled plate. After air cooling and water cooling, the temperature is reduced to the coiling temperature of 650℃.

[0052] Normalized pickling: open flame heats the strip to 480℃, the heating time is controlled at 44s, then rapidly heats to 950℃ at a rate of 15℃ / s, and the holding time is 4min; the pickling solution temperature is 75~80℃;

[0053] Cold rolling was carried out on a reversing mill with 6 passes to a target thickness of 0.35 mm.

[0054] Finally, the finished product is annealed. The heating section adopts a rapid heating method and is heated to 970°C at a heating rate of 45°C / s for 100s. The hydrogen gas volume fraction in the furnace is controlled at 10%; the dew point in the furnace is controlled at ≤-10°C; after annealing, the insulating coating is applied by a coating roller and cured at 440-570°C.

[0055] By adopting the above production method, a high-efficiency non-oriented electrical steel for industrial motors can be obtained. The magnetic properties of the finished product are P 1.5 / 50 =2.11W / kg, B 50 =1.72T, iron loss magnetic induction ratio: P 1.5 / 50 / B 50 =1.22.

[0056] Comparative Example 1

[0057] The chemical composition by weight percentage is: C: 0.0017%, Si: 2.45%, Mn: 0.48%, Als: 0.53%, Ti: 0.0017%, C+Ti: 0.0034%. The rest is Fe and unavoidable impurities;

[0058] The steel with the above chemical composition is subjected to molten iron pretreatment, converter steelmaking, vacuum treatment, and then continuously cast into a slab with a thickness of 200 to 300 mm;

[0059] The final rolling temperature of hot rolling is 880℃, and the hot rolled plate is rolled into 2.2mm thick hot rolled plate. After air cooling and water cooling, the temperature is reduced to 650℃ for coiling.

[0060] Normalized pickling: open flame heats the strip to 480℃, the heating time is controlled at 44s, then rapidly heats to 930℃ at a rate of 28℃ / s, and the holding time is 4min; the pickling solution temperature is 75~80℃;

[0061] Cold rolling was carried out on a reversing mill, with a target thickness of 0.35 mm in 6 passes;

[0062] Finally, the finished product is annealed. The heating section adopts a rapid heating method, heating to 970°C at a heating rate of 60°C / s for 100s. The hydrogen gas volume fraction in the furnace is controlled at 10%; the dew point in the furnace is controlled at ≤-10°C; after annealing, the insulating coating is applied by a coating roller and cured at 440-570°C.

[0063] By adopting the above production method, a high-efficiency non-oriented electrical steel for industrial motors can be obtained. The magnetic properties of the finished product are P 1.5 / 50 =2.33W / kg, B 50 =1.695T, iron loss magnetic induction ratio: P 1.5 / 50 / B 50 =1.37

[0064] Comparative Example 2

[0065] The chemical composition by weight percentage is: C: 0.0025%, Si: 2.45%, Mn: 0.48%, Als: 0.53%, Ti: 0.0024%, C+Ti: 0.0049%. The rest is Fe and unavoidable impurities;

[0066] The steel with the above chemical composition is subjected to molten iron pretreatment, converter steelmaking, vacuum treatment, and then continuously cast into a slab with a thickness of 200 to 300 mm;

[0067] The final rolling temperature of hot rolling is 880℃, and the hot rolled plate is rolled into a 2.2mm thick hot rolled plate. After air cooling and water cooling, the temperature is reduced to the coiling temperature of 650℃.

[0068] Normalized pickling: the strip is heated to 480℃ with an open flame, the heating time is controlled at 44s, and then rapidly heated to 930℃ at a speed of 13℃ / s, and the holding time is 5min; the pickling liquid temperature is 75~80℃;

[0069] After cold rolling on a reversing mill, the target thickness of 6 rolling passes is 0.35mm;

[0070] Finally, the finished product is annealed. The heating section adopts a rapid heating method, heating to 970°C at a heating rate of 30°C / s for 100s. The hydrogen gas volume fraction in the furnace is controlled at 10%; the dew point in the furnace is controlled at ≤-10°C; after annealing, the insulating coating is applied by a coating roller and cured at 440-570°C.

[0071] By adopting the above production method, a high-efficiency non-oriented electrical steel for industrial motors can be obtained. The magnetic properties of the finished product are P 1.5 / 50 =2.26W / kg, B 50 =1.683T, iron loss magnetic induction ratio: P 1.5 / 50 / B 50 =1.38.

[0072] like Figure 1 , Figure 2 As shown, Figure 1 is the normalized texture diagram of Comparative Example 1, Figure 2 The normalized texture of Example 1 is shown in Table 1. Compared with the normalized texture of Comparative Example 1, the texture type is basically unchanged, but the {110} <110> The orientation strength is improved.

[0073] like Figure 3 , Figure 4 As shown, Figure 3 The finished product texture diagram of Comparative Example 1, Figure 4 The finished product texture diagram of Example 1 shows that the α fiber texture, {110} <110> The texture strength is significantly reduced, the γ fiber texture strength is slightly reduced, and the Goss texture strength is enhanced.

Claims

1. A high-efficiency non-oriented electrical steel for industrial motors, characterized by: The chemical composition by weight percentage includes: 0.0010%≤C≤0.0020%, 2.2%≤Si≤2.5%, 0.3%≤Mn≤0.7%, 0.3%≤Als≤0.6%, 0.0010%≤Ti≤0.0020%, 0.0020%≤C+Ti≤0.0040%, and the rest is Fe and unavoidable impurities.

2. The high-efficiency non-oriented electrical steel for industrial motors according to claim 1, characterized in that: The C content is preferably 0.0017 to 0.0019%.

3. The high-efficiency non-oriented electrical steel for industrial motors according to claim 1, characterized in that: The Ti content is preferably 0.0017 to 0.0018%.

4. The high-efficiency non-oriented electrical steel for industrial motors according to claim 1, characterized in that: The C+Ti content is preferably 0.0034-0.0036%.

5. A method for preparing high-efficiency non-oriented electrical steel for industrial motors as claimed in claim 1, characterized in that: The preparation method is as follows: 1) The chemical composition according to claim 1 is subjected to hot metal pretreatment, converter steelmaking, vacuum treatment, and then continuously cast into a slab with a thickness of 200 to 300 mm; 2) Hot rolling: the final rolling temperature of hot rolling is 830-880°C and rolled into a hot rolled plate with a thickness of 2.2-2.6 mm. After air cooling and water cooling, the temperature is reduced to the coiling temperature of 650-680°C; 3) Normalized pickling: heat the strip to 450-550℃ with an open flame for 30-45s, then rapidly heat to 920-950℃ at a rate of 15-20℃ / s and keep warm for 2-5min; the temperature of the pickling solution is 75-80℃; 4) cold rolling on a reversing mill with multiple passes to a target thickness of 0.35 mm; 5) Finished product annealing, heating to 900-980°C at a heating rate of 40-50°C / s for 90-100s, with the hydrogen volume fraction in the furnace controlled at 5-10%; the dew point in the furnace controlled at ≤-10°C; after annealing, the insulating coating is applied by a coating roller and the insulating coating is cured; Magnetic properties of the steel obtained 1.5 / 50 =2.09~2.21W / kg, B 50 =1.70~1.72T, iron loss magnetic induction ratio: P 1.5 / 50 / B 50 =1.21~1.

30.

6. The method for preparing high-efficiency non-oriented electrical steel for industrial motors according to claim 5, characterized in that: The hot rolling is finished at a temperature of 860-880° C. to form a hot rolled plate with a thickness of 2.2-2.4 mm.

7. The method for preparing high-efficiency non-oriented electrical steel for industrial motors according to claim 5, characterized in that: The coiling temperature is 650-660°C.

8. The method for preparing high-efficiency non-oriented electrical steel for industrial motors according to claim 5, characterized in that: The open flame heating temperature is 480-500°C.

9. The method for preparing high-efficiency non-oriented electrical steel for industrial motors according to claim 5, characterized in that: The heating speed of the finished product annealing is 45-50°C / s, and the temperature is heated to 950-980°C.

10. The method for preparing high-efficiency non-oriented electrical steel for industrial motors according to claim 5, characterized in that: The insulating coating is cured at 440-570°C.

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