A method for producing new energy non-oriented electrical steel by cold continuous rolling process

Abstract

The application discloses a method for producing new energy non-oriented electrical steel by adopting a cold continuous rolling process, and comprises the following steps: smelting, continuous casting, heating in a heating furnace, hot rolling, normalizing, pickling, cold rolling, annealing and coating; characterized in that the non-oriented electrical steel comprises the following chemical element components and weight percentages: C is <=0.003%, Si is 2.2-3.0%, Mn is 0.2-0.4%, P is 0.015-0.035%, S is <=0.006%, Al is 0.3-0.5%, Ti is 0.002-0.004%, and the rest is Fe and inevitable impurities. The 0.35mm electrical steel is manufactured by controlling the chemical components in the steel and adopting suitable whole-process production control process and cold continuous rolling technology, and the finished product satisfies: iron loss P1.0 / 400 <=15.0 W / kg, magnetic induction J5000 >=1.66 T.

Description

Technical Field

[0001] This invention relates to the field of electrical steel manufacturing technology, and in particular to a method for producing new energy non-oriented electrical steel using a cold continuous rolling process. Background Technology

[0002] Non-oriented silicon steel for new energy vehicles, as a low-carbon, high-silicon electrical steel sheet, possesses excellent magnetic properties and processing performance, such as high magnetic induction intensity, low iron loss, high resistivity, and good magnetic aging properties. It is one of the important materials in the manufacturing of motors for new energy vehicles. As a key material in the manufacturing of motors for new energy vehicles, non-oriented silicon steel for new energy vehicles has broad development prospects. With the continuous expansion of the new energy vehicle market and the continuous advancement of technology, the demand for non-oriented silicon steel for new energy vehicles will continue to grow. At the same time, enterprises need to strengthen technological innovation and improve product competitiveness to meet the challenges in the market.

[0003] Reference 1 discloses non-oriented silicon steel for new energy drive motors and its production method. It uses a preheat-free single-stand cold rolling method to produce non-oriented electrical steel with thicknesses of 0.25 mm, 0.30 mm and 0.35 mm. While ensuring magnetic properties, it improves strength and achieves a balance between magnetic properties and strength. However, single-stand cold rolling affects rolling efficiency.

[0004] Reference 2 discloses a low-iron-loss, high-magnetic-induction cold-rolled non-oriented electrical steel for new energy vehicle drive motors and its production method. The method uses the addition of copper alloying elements to obtain electrical steel sheets with excellent high-frequency magnetic properties. The produced electrical steel products have excellent magnetic properties, but the addition of alloying elements increases the manufacturing cost.

[0005] Reference 3 discloses a manufacturing method for high-strength non-oriented silicon steel for drive motors of new energy vehicles. The high-strength non-oriented silicon steel is produced by thin strip continuous casting technology. The process is simple, easy to implement, energy-saving and environmentally friendly, but the magnetic properties of the finished product are poor. Summary of the Invention

[0006] The purpose of this invention is to provide a method for producing new energy non-oriented electrical steel using a cold continuous rolling process. By controlling the chemical composition of the steel and adopting a suitable whole-process production control process and cold continuous rolling technology, the 0.35mm electrical steel produced meets the following requirements: iron loss P1.0 / 400≤15.0W / kg, magnetic induction J5000≥1.66T.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0008] This invention discloses a method for producing non-oriented electrical steel for new energy applications using a cold continuous rolling process, comprising the following steps: smelting, continuous casting, heating in a heating furnace, hot rolling, normalizing, pickling, cold rolling, annealing, and coating; characterized in that: the non-oriented electrical steel comprises the following chemical element composition and weight percentage: C ≤0.003%, Si 2.2~3.0%, Mn 0.2~0.4%, P 0.015~0.035%, S≤0.006%, Al 0.3~0.5%, Ti 0.002~0.004%, with the remainder being Fe and unavoidable impurities;

[0009] In the heating process of the heating furnace, a multi-stage heating method is adopted. The preheating stage controls the heating temperature at 940-960℃, the first heating stage controls the heating temperature at 980-1100℃, the second heating stage controls the heating temperature at 1000-1200℃, the soaking stage controls the heating temperature at 1000-1200℃, and the furnace exit temperature is 1050-1150℃, ensuring a total furnace time of 200-350 minutes, of which the soaking time is controlled at ≥40 minutes.

[0010] In the continuous casting process, the billet size is 200-250×1000-1275mm, electromagnetic stirring is used, and the continuous casting speed is controlled at 1.0-2.0m / min;

[0011] In the hot rolling process, the roughing pass rolling speed is 1.5-4.5 m / s, the intermediate slab thickness is 30-50 mm, the final hot rolling temperature is 900-960℃, and the coiling temperature is 500-550℃. The cumulative reduction rate of F1-F6 is ≥90%, and the reduction rate of F7 is ≤10% to adjust the slab shape. The tension between stands in the finishing mill is 2-3 MPa. The thickness of the hot-rolled slab is 1.8-2.3 mm.

[0012] During the normalizing step, the normalizing temperature is 900-1000℃ and the temperature is held for 160-200s, so that the area of ​​the non-recrystallized structure is 10%-20%.

[0013] In the pickling step, hydrochloric acid is used for pickling, with a concentration of 80-120 g / L, a pickling tank temperature of 60-80℃, and a pickling running rate of 100-150 m / min to ensure good surface quality control of the strip steel.

[0014] In the cold rolling process, the cumulative reduction rate of the first three passes is ≥70%, and the reduction rate of the last stand is ≤6%.

[0015] In the annealing process, staged heating is adopted, which is carried out under a protective atmosphere. The staged annealing includes preheating, radiant heating annealing, and homogenization. The preheating temperature is 650-850℃, the radiant heating annealing temperature is 850-1000℃, and the strip residence time is 20-60s. The homogenization temperature is controlled between 950-1000℃, and the strip residence time is 20-50s. The cooling process is carried out under a reducing atmosphere. The strip passes through at a speed of 100-130m / s and is slowly cooled from the annealing cooling start temperature to 100-200℃ at a cooling rate of 9-26℃ / s. The dew point of the atmosphere is controlled between -40℃ and -10℃ during the annealing process.

[0016] During the coating process, the coating thickness is controlled at 2.0-3.0 g / m. 2 The sintering temperature is 500-700℃.

[0017] Furthermore, during the cold rolling process, the shape of the sheet is improved by simultaneously using slewing and bending rolls.

[0018] Furthermore, the cold-rolled thickness is 0.35 mm.

[0019] Furthermore, during the coating process, it is ensured that the color of the board surface is consistent, uniform, and without any missed areas after coating.

[0020] Furthermore, the produced electrical steel products meet the following requirements: iron loss P1.0 / 400≤15.0W / kg, magnetic induction B5000≥1.66T.

[0021] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0022] The cold-rolled non-oriented electrical steel produced using the method of this invention meets the performance requirements for non-oriented electrical steel used in drive motors of new energy vehicles. The product satisfies the following conditions: iron loss P10 / 400 ≤ 15.0 W / kg, minimum magnetic polarization J5000 ≥ 1.66 T, excellent magnetic properties, low iron loss, high magnetic flux density, and small magnetic property fluctuations, thus meeting the needs of users of drive motors for new energy vehicles. Attached Figure Description

[0023] The present invention will be further described below with reference to the accompanying drawings.

[0024] Figure 1 This is a schematic diagram of the metallographic structure of the new energy non-oriented electrical steel produced in Embodiment 1 of the present invention. Detailed Implementation

[0025] Example 1

[0026] This embodiment provides a method for producing new energy non-oriented electrical steel using a cold continuous rolling process, including the steps of smelting, continuous casting, heating in a heating furnace, hot rolling, normalizing, pickling, cold rolling, annealing, and coating. The cold-rolled non-oriented electrical steel of the entire process includes the following chemical element composition and weight percentage: C is 0.003%, Si is 2.8%, Mn is 0.3%, P is 0.025%, S is 0.006%, Al is 0.4%, Ti is 0.003%, and the remainder is Fe and unavoidable impurities.

[0027] In the heating process of the heating furnace, a multi-stage heating method is adopted. The preheating stage controls the heating temperature at 950℃, the first heating stage controls the heating temperature at 990℃, the second heating stage controls the heating temperature at 1180℃, the soaking stage controls the heating temperature at 1180℃, and the furnace exit temperature is 1180℃, ensuring a total furnace time of 250 minutes, of which the soaking time is controlled at 50 minutes.

[0028] In the continuous casting process, the billet size is 230×1175mm, electromagnetic stirring is used, and the continuous casting speed is controlled at 1.5m / min.

[0029] In the hot rolling process, the roughing pass rolling speed is 2.5 m / s, the intermediate slab thickness is 40 mm, the final hot rolling temperature is 950℃, and the coiling temperature is 530℃. The cumulative reduction rate from F1 to F6 is 91%, and the reduction rate from F7 is 8% to adjust the slab shape. The tension between the stands on the finishing mill is 2 MPa. The thickness of the hot-rolled slab is 2.2 mm.

[0030] In the normalizing step, the normalizing temperature is 950℃ and the holding time is 180s, so that the area of ​​the non-recrystallized structure is 15%.

[0031] In the pickling step, hydrochloric acid is used for pickling, with a concentration of 90 g / L, a pickling tank temperature of 70℃, and a pickling operation rate of 120 m / min to ensure good surface quality control of the strip steel.

[0032] In the cold rolling process, the cumulative reduction rate of the first three passes is 80%, and the reduction rate of the last stand is 5%. At the same time, the shape of the sheet is improved by using the shifting rolls and bending rolls. The cold rolling thickness is 0.35mm.

[0033] In the annealing process, staged heating is adopted, which is carried out under a protective atmosphere. The staged annealing includes preheating, radiation heating annealing, and homogenization. The preheating temperature is 750℃, the radiation heating annealing temperature is 950℃, the strip dwell time is 55s, the homogenization temperature is controlled between 980℃, and the strip dwell time is 30s. The cooling process is carried out under a reducing atmosphere. The strip passes through at a speed of 110m / s and is slowly cooled from the annealing cooling start temperature to 150℃ at a cooling rate of 15℃ / s. The atmosphere dew point is controlled at -30℃ during the annealing process.

[0034] During the coating process, the coating thickness is controlled at 2.5 g / m. 2 The sintering temperature is 530℃ to ensure that the color of the coated board is consistent, uniform, and without any missed areas.

[0035] The produced electrical steel products have an iron loss of 14.8 W / kg (P1.0 / 400) and a magnetic induction of 1.68 T (B5000).

[0036] Example 2

[0037] This embodiment provides a method for producing new energy non-oriented electrical steel using a cold continuous rolling process, including the steps of smelting, continuous casting, heating in a heating furnace, hot rolling, normalizing, pickling, cold rolling, annealing, and coating. The cold-rolled non-oriented electrical steel of the entire process includes the following chemical element composition and weight percentage: C is 0.003%, Si is 2.6%, Mn is 0.25%, P is 0.028%, S is 0.006%, Al is 0.35%, Ti is 0.003%, and the remainder is Fe and unavoidable impurities.

[0038] In the heating process of the heating furnace, a multi-stage heating method is adopted. The preheating stage controls the heating temperature at 960℃, the first heating stage controls the heating temperature at 1000℃, the second heating stage controls the heating temperature at 1190℃, the soaking stage controls the heating temperature at 1190℃, and the furnace exit temperature is 1190℃, ensuring a total furnace time of 260 minutes, of which the soaking time is controlled at 50 minutes.

[0039] In the continuous casting process, the billet size is 230×1185mm, electromagnetic stirring is used, and the continuous casting speed is controlled at 1.7m / min.

[0040] In the hot rolling process, the roughing pass rolling speed is 2.7 m / s, the intermediate slab thickness is 45 mm, the final hot rolling temperature is 960℃, and the coiling temperature is 540℃. The cumulative reduction rate from F1 to F6 is 92%, and the reduction rate from F7 is 7% to adjust the slab shape. The tension between the stands on the finishing mill is 2 MPa. The thickness of the hot-rolled slab is 2.3 mm.

[0041] In the normalizing step, the normalizing temperature is 960℃ and the holding time is 190s, so that the area of ​​the non-recrystallized structure is 13%;

[0042] In the pickling step, hydrochloric acid is used for pickling, with a concentration of 90 g / L, a pickling tank temperature of 60℃, and a pickling operation rate of 110 m / min to ensure good surface quality control of the strip steel.

[0043] In the cold rolling process, the cumulative reduction rate of the first three passes is 80%, and the reduction rate of the last stand is 5%. At the same time, the shape of the sheet is improved by using the shifting rolls and bending rolls. The cold rolling thickness is 0.35mm.

[0044] In the annealing process, staged heating is adopted, which is carried out under a protective atmosphere. The staged annealing includes preheating, radiant heating annealing, and homogenization. The preheating temperature is 760℃, the radiant heating annealing temperature is 960℃, the strip dwell time is 55s, the homogenization temperature is controlled between 990℃, and the strip dwell time is 30s. The cooling process is carried out under a reducing atmosphere. The strip passes through at a speed of 120m / s and is slowly cooled from the annealing cooling start temperature to 200℃ at a cooling rate of 18℃ / s. The atmosphere dew point is controlled at -35℃ during the annealing process.

[0045] During the coating process, the coating thickness is controlled at 2.7 g / m. 2 The sintering temperature is 540℃ to ensure that the color of the coated board is consistent, uniform, and without any missed areas.

[0046] The produced electrical steel products have an iron loss of 13.3 W / kg (P1.0 / 400) and a magnetic induction of 1.66 T (B5000).

[0047] Example 3

[0048] This embodiment provides a method for producing new energy non-oriented electrical steel using a cold continuous rolling process, including the steps of smelting, continuous casting, heating in a heating furnace, hot rolling, normalizing, pickling, cold rolling, annealing, and coating. The cold-rolled non-oriented electrical steel of the entire process includes the following chemical element composition and weight percentage: C is 0.003%, Si is 2.5%, Mn is 0.35%, P is 0.025%, S is 0.006%, Al is 0.35%, Ti is 0.003%, and the remainder is Fe and unavoidable impurities.

[0049] In the heating process of the heating furnace, a multi-stage heating method is adopted. The preheating stage controls the heating temperature at 940℃, the first heating stage controls the heating temperature at 980℃, the second heating stage controls the heating temperature at 1170℃, the soaking stage controls the heating temperature at 1170℃, and the furnace exit temperature is 1170℃, ensuring a total furnace time of 260 minutes, of which the soaking time is controlled at 60 minutes.

[0050] In the continuous casting process, the billet size is 230×1185mm, electromagnetic stirring is used, and the continuous casting speed is controlled at 1.5m / min.

[0051] In the hot rolling process, the roughing pass rolling speed is 2.6 m / s, the intermediate slab thickness is 45 mm, the final hot rolling temperature is 940℃, and the coiling temperature is 520℃. The cumulative reduction rate from F1 to F6 is 90%, and the reduction rate from F7 is 8% to adjust the slab shape. The tension between the stands on the finishing mill is 3 MPa. The thickness of the hot-rolled slab is 2.0 mm.

[0052] In the normalizing step, the normalizing temperature is 940℃ and the holding time is 180s, so that the area of ​​the non-recrystallized structure is 10%.

[0053] In the pickling step, hydrochloric acid is used for pickling, with a concentration of 90 g / L, a pickling tank temperature of 70℃, and a pickling operation rate of 120 m / min to ensure good surface quality control of the strip steel.

[0054] In the cold rolling process, the cumulative reduction rate of the first three passes is 80%, and the reduction rate of the last stand is 5%. At the same time, the shape of the sheet is improved by using the shifting rolls and bending rolls. The cold rolling thickness is 0.35mm.

[0055] In the annealing process, staged heating is adopted, which is carried out under a protective atmosphere. The staged annealing includes preheating, radiation heating annealing, and homogenization. The preheating temperature is 740℃, the radiation heating annealing temperature is 940℃, the strip dwell time is 60s, the homogenization temperature is controlled at 970℃, and the strip dwell time is 35s. The cooling process is carried out under a reducing atmosphere. The strip passes through at a speed of 110m / s and is slowly cooled from the annealing cooling start temperature to 140℃ at a cooling rate of 15℃ / s. The atmosphere dew point is controlled at -30℃ during the annealing process.

[0056] During the coating process, the coating thickness is controlled at 2.8 g / m. 2 The sintering temperature is 520℃ to ensure that the color of the coated board is consistent, uniform, and without any missed areas.

[0057] The produced electrical steel products have an iron loss of 14.3 W / kg (P1.0 / 400) and a magnetic induction of 1.67 T (B5000).

[0058] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for producing new energy non-oriented electrical steel using a cold continuous rolling process, comprising the following steps: smelting, continuous casting, furnace heating, hot rolling, normalizing, pickling, cold rolling, annealing, and coating; characterized in that: The non-oriented electrical steel comprises the following chemical element composition and weight percentage: C ≤0.003%, Si 2.2-3.0%, Mn 0.2-0.4%, P 0.015-0.035%, S ≤0.006%, Al 0.3-0.5%, Ti 0.002-0.004%, with the remainder being Fe and unavoidable impurities; In the heating process of the heating furnace, a multi-stage heating method is adopted. The preheating stage controls the heating temperature at 940-960℃, the first heating stage controls the heating temperature at 980-1100℃, the second heating stage controls the heating temperature at 1000-1200℃, the soaking stage controls the heating temperature at 1000-1200℃, and the furnace exit temperature is 1050-1150℃, ensuring a total furnace time of 200-350 minutes, of which the soaking time is controlled at ≥40 minutes. In the continuous casting process, the billet size is 200-250×1000-1275mm, electromagnetic stirring is used, and the continuous casting speed is controlled at 1.0-2.0m / min; In the hot rolling process, the roughing pass rolling speed is 1.5-4.5 m / s, the intermediate slab thickness is 30-50 mm, the final hot rolling temperature is 900-960℃, and the coiling temperature is 500-550℃; the cumulative reduction rate of F1-F6 is ≥90%, and the reduction rate of F7 is ≤10% to adjust the slab shape; the tension between stands of the finishing mill is 2-3 MPa; the thickness of the hot-rolled slab is 1.8-2.3 mm. During the normalizing step, the normalizing temperature is 900-1000℃ and the temperature is held for 160-200s, so that the area of ​​the non-recrystallized structure is 10%-20%. In the pickling step, hydrochloric acid is used for pickling, with a concentration of 80-120 g / L, a pickling tank temperature of 60-80℃, and a pickling running rate of 100-150 m / min to ensure good surface quality control of the strip steel. In the cold rolling process, the cumulative reduction rate of the first three passes is ≥70%, and the reduction rate of the last stand is ≤6%. The annealing process employs staged heating under a protective atmosphere, including preheating, radiant heating, and homogenization. The preheating temperature is 650-850℃, the radiant heating temperature is 850-1000℃ with a strip dwell time of 20-60 seconds, and the homogenization temperature is controlled between 950-1000℃ with a strip dwell time of 20-50 seconds. The cooling process is carried out under a reducing atmosphere, with the strip passing through at a speed of 100-130 m / s and cooled slowly from the initial annealing temperature to 100-200℃ at a cooling rate of 9-26℃ / s. The atmosphere dew point is controlled between -40℃ and 10℃ during the annealing process. During the coating process, the coating thickness is controlled at 2.0-3.0 g / m. 2 The sintering temperature is 500-700℃.

2. The method for producing new energy non-oriented electrical steel using a cold continuous rolling process according to claim 1, characterized in that: During the cold rolling process, roll shifting and bending are used simultaneously to control and improve the sheet shape.

3. The method for producing new energy non-oriented electrical steel using a cold continuous rolling process according to claim 2, characterized in that: The cold-rolled thickness is 0.35mm.

4. The method for producing new energy non-oriented electrical steel using a cold continuous rolling process according to claim 1, characterized in that: During the coating process, ensure that the color of the board surface is consistent, uniform, and without any missed areas.

5. The method for producing new energy non-oriented electrical steel using a cold continuous rolling process according to claim 1, characterized in that: The produced electrical steel products meet the following requirements: iron loss P1.0 / 400≤15.0W / kg, magnetic induction B5000≥1.66T.

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