Non-oriented silicon steel with excellent electromagnetic properties in high temperature environment and manufacturing method thereof

Abstract

The application discloses a non-oriented silicon steel with excellent electromagnetic performance in high-temperature environment and a manufacturing method thereof. The chemical composition of the non-oriented silicon steel comprises the following components by weight percentage: C is less than or equal to 0.0020%, 3.2% less than or equal to Si less than or equal to 3.5%, 0.3% less than or equal to Mn less than or equal to 0.7%, 0.5% less than or equal to Al less than or equal to 0.8%, Ti less than or equal to 0.0020%, 0.03% less than or equal to Sn less than or equal to 0.07%, C+Ti less than or equal to 0.0038%, and the rest is Fe and inevitable impurities. The manufacturing method comprises the following specific steps: molten iron pretreatment, converter smelting and continuous casting into a slab; hot rolling of the slab; normalizing treatment of the hot-rolled plate; cold rolling of the hot-rolled plate; and annealing. The application optimizes the structure of the magnetic domain in the crystal grain and enhances the magnetization capacity of the non-oriented silicon steel in a high-temperature state.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of metallurgy, and particularly relates to an oriented silicon steel with excellent electromagnetic properties in high-temperature environment and a manufacturing method thereof. BACKGROUND

[0002] A motor generates a large amount of heat when it rotates at high speed, causing the temperature of the iron core to rise rapidly, and the maximum temperature can even rise to 200℃. Studies have shown that a higher ambient temperature can change the magnetic domain state of non-oriented silicon steel, thereby affecting the magnetic properties of non-oriented silicon steel, resulting in reduced performance of the driving motor at high temperature and affecting the overall efficiency of the motor.

[0003] A Chinese patent specification discloses a non-oriented silicon steel for high-speed motors and a preparation method thereof (publication number CN115198198 A), which has a chemical composition by weight percentage comprising: C≤0.002%, S≤0.001%, N≤0.003%, Si: 3.0~3.4%, Al: 0.80~1.0%, Mn: 0.2~0.4%, P≤0.01%, Sn+Sb≤0.004%, Nb≤0.005%, V≤0.005%, Ti≤0.005%, Mo≤0.005%, Cr≤0.05%, Ni≤0.05%, Cu≤0.05%, 0<C+S+N≤0.005%; the yield strength of the final product is≥550MPa, the magnetic induction B5000 is≥1.65, the high-frequency iron loss P1.0 / 1000 at a thickness of 0.30mm is≤45W / kg, the high-frequency iron loss P1.0 / 1000 at a thickness of 0.25mm is≤40W / kg, and the high-frequency iron loss P1.0 / 1000 at a thickness of 0.20mm is≤35W / kg.

[0004] A Chinese patent specification also discloses a non-oriented silicon steel for high-speed rotors with a yield strength of 600MPa (publication number CN 107974620 B), which has a chemical composition by weight percentage comprising: C: 0.001~0.003%, Si: 2.6~3.4%, Mn: 0.20~0.6%, P≤0.005%, S≤0.005%, Al 0.75~0.95%, N 0.002~0.006%, Nb 0.053~0.2%. The yield strength of the non-oriented silicon steel is≥600MPa, the tensile strength is≥700MPa, P1.0 / 400≤35W / kg, and B5000≥1.60T for a finished product with a thickness not exceeding 0.35mm.

[0005] The magnetic properties of the finished product of the above non-oriented silicon steel are all at room temperature, and the magnetic properties of the non-oriented silicon steel in a high temperature environment are not involved. In a high temperature environment, the magnetic domain distribution of the non-oriented silicon steel material is more chaotic, and the domain wall movement resistance and magnetic domain rotation resistance will be significantly increased, so the magnetic induction of the non-oriented silicon steel in a high temperature environment is lower than that at room temperature or low temperature. SUMMARY

[0006] I. Technical problems to be solved

[0007] The present application provides a non-oriented silicon steel with excellent electromagnetic properties in a high temperature environment and a manufacturing method thereof, and aims to provide a non-oriented silicon steel capable of achieving a magnetic induction B50 of 1.67-1.68T on the basis of P1.0 / 1000=46-50W / kg in an environment temperature of 200℃, and solving the problem of significant reduction of magnetic induction of the non-oriented silicon steel in a high temperature environment in the prior art.

[0008] II. Technical solutions

[0009] In order to achieve the above-mentioned purpose, the present application adopts the following technical solutions.

[0010] The non-oriented silicon steel has the following chemical composition by weight percentage: C≤0.0020%, 3.2%≤Si≤3.5%, 0.3%≤Mn≤0.7%, 0.5%≤Als≤0.8%, Ti≤0.0020%, 0.03%≤Sn≤0.07%, C+Ti≤0.0038%, and the rest is Fe and inevitable impurities.

[0011] By controlling the contents of impurity elements C and Ti, the number of fine inclusions is controlled, the "nailing" of fine inclusions to magnetic domain walls is reduced, and the resistance of magnetic domain rotation and domain wall movement is reduced, so as to optimize the electromagnetic properties in a high temperature environment.

[0012] The manufacturing method of the non-oriented silicon steel mainly adopts a rapid heating mode in the annealing process, increases the temperature of the high temperature section, and increases the temperature of the strip steel to a higher temperature in a shorter time, reduces the proportion of the {111} texture component of the adverse texture, and increases the proportion of the cubic texture, Goss texture and other components. At the same time, the grain size of the finished product of the non-oriented silicon steel with high Si component system is controlled within the range of 80-90μm, and the hindering effect of the grain boundary on the magnetic domain rotation and domain wall movement is reduced. Specifically, the following steps are included:

[0013] 1) The molten iron with the above-mentioned chemical composition by weight percentage is pretreated, then is smelted by a converter, is treated in vacuum, and is continuously cast into a slab with a thickness of 200-300mm;

[0014] 2) hot rolling the slab, the finishing temperature of the hot rolling is controlled at 830-880℃, the hot rolling plate with thickness of 2.2-2.6mm is formed, and the temperature is reduced to 630-670℃ after air cooling and water cooling process;

[0015] 3) normalizing the hot rolling plate, the normalizing temperature is controlled at 840-880℃, and the normalizing time is 2-5min;

[0016] 4) pickling the plate coil, the pickling temperature is 75-80℃;

[0017] 5) cold rolling the hot rolling plate, the target thickness is 0.30mm;

[0018] 6) annealing, the heating section adopts rapid heating mode, the heating section temperature is 900-1020℃, the time is 100-110s, the hydrogen volume fraction in the furnace is controlled at 5-10%, and the dew point in the furnace is controlled at ≤-10℃;

[0019] 7) after annealing, the insulation coating is coated by coating roller, and the insulation coating is solidified at the temperature of 440-570℃.

[0020] In step 4), the cold rolling is rolled by 6 passes.

[0021] III. Beneficial effects

[0022] The manufacturing method of the non-oriented silicon steel adopted in the application optimizes the structure of the magnetic domain in the grain, is beneficial to the movement of the magnetic domain wall, enhances the magnetization capacity of the non-oriented silicon steel at high temperature, and obtains the non-oriented silicon steel with magnetic induction B50 of 1.67T-1.68T on the basis of P1.0 / 1000=46-50W / kg at the environmental temperature of 200℃, and solves the problem that the magnetic induction of the non-oriented silicon steel in the prior art is significantly reduced in the high temperature environment. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is the recrystallization structure obtained after annealing of the example 1 of the application.

[0024] Figure 2 is the recrystallization structure obtained after annealing of the example 2 of the application.

[0025] Figure 3 is the recrystallization structure obtained after annealing of the comparative example 1.

[0026] Figure 4 is the recrystallization structure obtained after annealing of the comparative example 2.

[0027] Figure 5 is the recrystallization structure obtained after annealing of the comparative example 3. DETAILED DESCRIPTION

[0028] The technical solutions of the present application will be further described in detail below in combination with the drawings and specific embodiments, so that those skilled in the art can have a clearer understanding.

[0029] Embodiment 1

[0030] The non-oriented silicon steel of the embodiment 1 of the present application has the following chemical composition by weight percentage: C: 0.0017%, Si: 3.33%, Mn: 0.50%, Als: 0.647%, Ti: 0.0017%, Sn: 0.047%, C+Ti: 0.0034%, and the rest is Fe and inevitable impurities.

[0031] The manufacturing method of the non-oriented silicon steel comprises the following specific steps:

[0032] 1) The molten iron with the above chemical composition by weight percentage is pretreated, and then is smelted by converter, treated by vacuum, and continuously cast into a slab with a thickness of 200-300mm;

[0033] 2) The slab is hot-rolled, and the final rolling temperature is controlled at 830-880℃, and the hot-rolled plate with a thickness of 2.2-2.6mm is rolled, and the temperature is reduced to the coiling temperature of 630-670℃ by air cooling and water cooling process;

[0034] 3) The hot-rolled plate is normalized, and the normalizing temperature is controlled at 850℃, and the normalizing time is 2-5min;

[0035] 4) The plate coil is pickled, and the pickling temperature is 75-80℃;

[0036] 5) The hot-rolled plate is cold-rolled by reversible rolling mill, and is rolled by 6 passes, and the target thickness is 0.30mm; 6) The finished product is annealed, the heating section adopts rapid heating mode, the heating section temperature is 1020℃, the time is 100s, the hydrogen volume fraction in the furnace is controlled at 5-10%, and the dew point in the furnace is controlled at ≤-10℃;

[0037] 7) After annealing, the insulation coating is applied by coating roller, and the insulation coating is solidified at a temperature of 440-570℃.

[0038] Finally, a non-oriented silicon steel with excellent electromagnetic performance in high-temperature environment is obtained, the grain size of the finished product is 88μm, the magnetic performance P1.0 / 1000 of the finished product at the environmental temperature of 200℃ is 46.1W / kg, and B50 is 1.675T.

[0039] Embodiment 2

[0040] The non-oriented silicon steel of the embodiment 2 has the following chemical components: C: 0.0016%, Si: 3.35%, Mn: 0.51%, Al: 0.68%, Ti: 0.0016%, Sn: 0.051%, C+Ti: 0.0032%, and the rest is Fe and inevitable impurities.

[0041] The manufacturing method of the non-oriented silicon steel comprises the following specific steps:

[0042] 1) The molten iron with the above chemical components is pretreated, and then is smelted by a converter, and is continuously cast into a slab with a thickness of 200-300 mm after vacuum treatment;

[0043] 2) The slab is hot-rolled, and the final rolling temperature is controlled to be 830-880 ℃, and the hot-rolled plate with a thickness of 2.2-2.6 mm is rolled, and the temperature is reduced to the coiling temperature of 630-670 ℃ after air cooling and water cooling processes;

[0044] 3) The hot-rolled plate is normalized, and the normalizing temperature is controlled to be 870 ℃, and the normalizing time is 2-5 min;

[0045] 4) The plate coil is pickled, and the pickling temperature is 75-80 ℃;

[0046] 5) The hot-rolled plate is cold-rolled by a reversible rolling mill, and is rolled by 6 passes, and the target thickness is 0.30 mm;

[0047] 6) The finished product is annealed, the heating section adopts a rapid heating mode, the heating section temperature is 1010 ℃, the time is 105 s, the hydrogen volume fraction in the furnace is controlled to be 5-10%, and the dew point in the furnace is controlled to be ≤-10 ℃;

[0048] 7) After annealing, the insulation coating is applied by a coating roller, and the insulation coating is solidified at a temperature of 440-570 ℃.

[0049] Finally, the non-oriented silicon steel with excellent electromagnetic properties in a high-temperature environment is obtained, the grain size of the finished product is 86 μm, the finished product magnetic property P1.0 / 1000=47.8 W / kg, and B50=1.677 T at an environmental temperature of 200 ℃.

[0050] Comparative example 1

[0051] The non-oriented silicon steel of the comparative example 1 has the following chemical components: C: 0.0025%, Si: 3.33%, Mn: 0.5%, Al: 0.647%, Ti: 0.0017%, Sn: 0.047%, C+Ti: 0.0042%, and the rest is Fe and inevitable impurities.

[0052] 1) The molten iron with the above chemical composition is pretreated, smelted by converter, and after vacuum treatment, is continuously cast into slab with thickness of 200-300 mm;

[0053] 2) The slab is hot-rolled, and the finishing temperature of the hot-rolling is controlled at 830-880℃, and is rolled into hot-rolled plate with thickness of 2.2-2.6 mm, and after air cooling and water cooling process, the temperature is reduced to coiling temperature of 630-670℃;

[0054] 3) Normalizing treatment, the normalizing temperature is controlled at 850℃, and the normalizing time is 2-5 min;

[0055] 4) The plate coil is pickled, and the pickling temperature is 75-80℃;

[0056] 5) The hot-rolled plate is cold-rolled by reversible rolling mill, and after 6 passes of rolling, the target thickness is 0.3 mm;

[0057] 6) The finished product is annealed, the heating section adopts rapid heating mode, the heating section temperature is 1020℃, the time is 105 s, the hydrogen volume fraction in the furnace is controlled at 5-10%, and the dew point in the furnace is controlled at ≤-10℃;

[0058] 7) After annealing, the insulation coating is applied by coating roller, and the insulation coating is solidified by temperature of 440-570℃.

[0059] The non-oriented silicon steel manufactured by the above method has finished product grain size of 69 μm, and at ambient temperature of 200℃, the finished product magnetic property P1.0 / 1000 = 62.5 W / kg, B50 = 1.661 T.

[0060] Comparative Example 2

[0061] The non-oriented silicon steel of Comparative Example 2 has chemical composition with weight percentage of C: 0.0017%, Si: 3.35%, Mn: 0.51%, Als: 0.68%, Ti: 0.0016%, Sn: 0.051%, C+Ti: 0.0033%, and the rest is Fe and inevitable impurities.

[0062] 1) The molten iron with the above chemical composition is pretreated, smelted by converter, and after vacuum treatment, is continuously cast into slab with thickness of 200-300 mm;

[0063] 2) The slab is hot-rolled, and the finishing temperature of the hot-rolling is controlled at 830-880℃, and is rolled into hot-rolled plate with thickness of 2.2-2.6 mm, and after air cooling and water cooling process, the temperature is reduced to coiling temperature of 630-670℃;

[0064] 3) Normalizing treatment, the normalizing temperature is controlled at 830℃, and the normalizing time is 2-5 min;

[0065] 4) The plate coil is pickled at a temperature of 75-80°C;

[0066] 5) The hot-rolled plate is cold-rolled by a reversible rolling mill, and is rolled for 6 passes to a target thickness of 0.3 mm;

[0067] 6) The finished product is annealed, the heating section adopts a rapid heating mode, the heating section temperature is 1020°C, the time is 105s, the hydrogen volume fraction in the furnace is controlled at 5-10%, and the dew point in the furnace is controlled at ≤-10°C;

[0068] 7) After annealing, the insulation coating is applied by a coating roller, and the insulation coating is cured at a temperature of 440-570°C.

[0069] The grain size of the non-oriented silicon steel manufactured by the above method is 70 μm, the finished product magnetic property P1.0 / 1000=65 W / kg, B50=1.662 T at an ambient temperature of 200°C.

[0070] Comparative Example 3

[0071] The non-oriented silicon steel of Comparative Example 3 has the following chemical composition by weight percentage: C: 0.0017%, Si: 3.35%, Mn: 0.51%, Als: 0.68%, Ti: 0.0016%, Sn: 0.051%, C+Ti: 0.0033%, and the rest is Fe and inevitable impurities.

[0072] 1) The molten iron with the above chemical composition by weight percentage is pretreated, and is smelted by a converter, and is continuously cast into a slab with a thickness of 200-300 mm after vacuum treatment;

[0073] 2) The slab is hot-rolled, and the final rolling temperature is controlled at 830-880°C, and is rolled into a hot-rolled plate with a thickness of 2.2-2.6 mm, and the temperature is reduced to a coiling temperature of 630-670°C after air cooling and water cooling processes;

[0074] 3) Normalizing treatment, the normalizing temperature is controlled at 870°C, and the normalizing time is 2-5 min;

[0075] 4) The plate coil is pickled at a temperature of 75-80°C;

[0076] 5) The hot-rolled plate is cold-rolled by a reversible rolling mill, and is rolled for 6 passes to a target thickness of 0.3 mm;

[0077] 6) The finished product is annealed, the heating section adopts a rapid heating mode, the heating section temperature is 980°C, the time is 105s, the hydrogen volume fraction in the furnace is controlled at 5-10%, and the dew point in the furnace is controlled at ≤-10°C;

[0078] 7) after annealing, coating roll is used to coat insulating paint, and the insulating paint is cured at a temperature of 440-570℃.

[0079] The grain size of the finished product of the non-oriented silicon steel manufactured by the method is 68μm, the finished product has a magnetic property of P1.0 / 1000=68W / kg and B50=1.657T at an ambient temperature of 200℃.

[0080] As can be seen from the above comparison, the manufacturing method of the non-oriented silicon steel adopted by the present application optimizes the structure of the magnetic domain in the grain, is beneficial to the movement of the magnetic domain wall, and enhances the magnetization capacity of the non-oriented silicon steel at high temperature, thereby obtaining the non-oriented silicon steel which can have a magnetic induction B50 of 1.67-1.68T on the basis of P1.0 / 1000=46-50W / kg at an ambient temperature of 200℃, and solves the problem of significant reduction of the magnetic induction of the non-oriented silicon steel in the high temperature environment in the prior art.

Claims

1. A method for manufacturing non-oriented silicon steel with excellent electromagnetic properties in high-temperature environments, characterized in that, The non-oriented silicon steel has the following chemical composition by weight percentage: C≤0.002%, 3.2%≤Si≤3.5%, 0.3%≤Mn≤0.7%, 0.5%≤Als≤0.8%, Ti≤0.002%, 0.03%≤Sn≤0.07%, C+Ti≤0.0038%, with the remainder being Fe and unavoidable impurities; The manufacturing method of the non-oriented silicon steel includes the following specific steps: 1) The molten iron with the above chemical composition by weight percentage is pretreated, then smelted in a converter, vacuum treated and continuously cast into a slab with a thickness of 200-300mm. 2) The slab is hot rolled, and the final rolling temperature is controlled at 830-880℃ to produce a hot-rolled plate with a thickness of 2.2-2.6mm. After air cooling and water cooling processes, the temperature is reduced to a coiling temperature of 630-670℃. 3) Normalize the hot-rolled plate at a temperature of 840-880℃ for 2-5 minutes. 4) Pickle the coil at a temperature of 75-80℃; 5) Cold roll the hot-rolled plate to a target thickness of 0.30 mm; 6) Annealing: The heating section adopts a rapid heating method, with a heating temperature of 900-1020℃ and a time of 100-110s. The hydrogen gas integral in the furnace is controlled at 5-10%, and the dew point in the furnace is controlled at ≤-10℃. 7) After annealing, the insulating coating is applied through a coating roller and cured at a temperature of 440-570℃.

2. The method for manufacturing non-oriented silicon steel according to claim 1, characterized in that: In step 4), the cold rolling process involves six passes.

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